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Can near-infrared energy reach the brain for treatment of TBI? - Video abstract [78182]

Larry D. Morries, Theodore A. Henderson MD, PhD - 2015 (Video)
This research was done under the supervision of NASA and seems to be some of the most independent research comparing therapy laser parameters.
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This video was created to support their published research. The authors did research using several lasers and slices of a sheep’s brain to try and determine the best parameter for treating TBI (Traumatic Brain Injury) with a desired fluency of 0.9 to 15 joules/cm2 at a depth of 2 cm. They state that getting the energy through the skull is especially difficult so they test multiple options so test the transfer rate. They started out using a continuous output split 980/810nm system (the only company that makes that type of split system, 80% of the power at 980nm and 20% of the power at 810nm, is LiteCure with their LightForce series). The result was less than 1/2% of the energy reached a depth of 2cm. Then they switched to pulsing and got an increase in the energy transfer. When they switched to a 810nm-only 15 watt system with pulsing the transfer rate increased to 16% of the output energy reached the target depth.

 Here are some rough numbers to review the feasibility of using this system for treatment. If the duty cycle is 70%, the system will deliver 1.68 joules per second at a depth 2cm (15wattS*70%*16%). To get 5 joules/cm2 over 15 x 15 cm treatment area would require a total of 1125 joules at depth. This would take 23 minutes.

This research shows that only class 4 systems can delivery the level of power needed for this kind of therapy in a typical rushed doctor's office. A class 3b system with 1 watt would take 4 - 5 hours per treatment to get the same dosage.

The original research publication is titled " Treatments for traumatic brain injury with emphasis on transcranial near-infrared laser phototherapy"


video length: (9:18)

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Review of transcranial photobiomodulation for major depressive disorder: targeting brain metabolism, inflammation, oxidative stress, and neurogenesis

Paolo Cassano; Samuel R. Petrie; Michael R. Hamblin; Theodore A. Henderson; Dan V. Iosifescu; - Neurophotonics, 3(3), 031404 (2016). doi:10.1117/1.NPh.3.3.031404 March 4, 2016 (Publication)
This study shows some of the most detailed parameters (power, wavelenght, dosage) for working with the brain and seems to be unbiased because of the diverse background of authors..
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We examined the use of near-infrared and red radiation (photobiomodulation, PBM) for treating major depressive disorder (MDD). While still experimental, preliminary data on the use of PBM for brain disorders are promising. PBM is low-cost with potential for wide dissemination; further research on PBM is sorely needed. We found clinical and preclinical studies via PubMed search (2015), using the following keywords: “near-infrared radiation,” “NIR,” “low-level light therapy,” “low-level laser therapy,” or “LLLT” plus “depression.” We chose clinically focused studies and excluded studies involving near-infrared spectroscopy. In addition, we used PubMed to find articles that examine the link between PBM and relevant biological processes including metabolism, inflammation, oxidative stress, and neurogenesis. Studies suggest the processes aforementioned are potentially effective targets for PBM to treat depression. There is also clinical preliminary evidence suggesting the efficacy of PBM in treating MDD, and comorbid anxiety disorders, suicidal ideation, and traumatic brain injury. Based on the data collected to date, PBM appears to be a promising treatment for depression that is safe and well-tolerated. However, large randomized controlled trials are still needed to establish the safety and effectiveness of this new treatment for MDD.



Infrared (IR) light is ubiquitously present to most life on the earth. Of the total amount of solar energy reaching the human skin, 54% is IR and 30% is IR type A—near-infrared—(NIR; with a wavelength range of 760 to 1440 nm),1 which penetrates through the human skin and reaches deeply into tissue, depending on wavelength and energy.2

NIR is used to treat a variety of conditions such as muscle pain,3 wounds,4 neuropathic pain,5 and headache.6 NIR is also used for wellness and lifestyle purposes such as for cosmetic improvement in peri-orbital wrinkles.7,8 The clinical use of NIR light applied in NIR-spectroscopy dates from the mid-1980s, when it was used for monitoring of the brain in the neonate and the fetus.9

The use of transcranial phototherapy for treating brain disorders started with its application to acute stroke. Numerous preclinical animal studies1011.12 suggested that the application of NIR laser (810 nm) to the head at various times (hours) after induction of an acute stroke had beneficial effects on subsequent neurological performance and reduced lesion size. Evidence was obtained for the anti-inflammatory, anti-apoptotic, and proneurogenesis effects in the brain stimulated by this approach.13,14 These promising animal studies led to the conduction of a series of clinical trials called NeuroThera Effectiveness and Safety Trials (NEST). All together there were three large studies conducted in 1410 stroke patients [NEST-1 (n=120" role="presentation">n=120

), NEST-2 (n=660" role="presentation">n=660), NEST-3 (n=630" role="presentation">n=630

)] that demonstrated that NIR light delivered transcranially with a class-IV laser is safe, with no significant differences in rates of adverse events with NIR, when compared to sham exposure.1516.17 Other preclinical studies and clinical trials have suggested that transcranial photobiomodulation (PBM: laser or light emitting diodes—LED) is safe and effective for acute1819.20.21.22 and chronic2324.25 traumatic brain injury (TBI) and has beneficial effects on neurodegenerative diseases (Alzheimer’s and Parkinson’s).26,27

For the transcranial treatment of major depressive disorder (MDD), both PBM LEDs and lasers have been experimentally tested, although PBM is not FDA-approved for the treatment of MDD. Certain forms of PBM treatment are also referred to as low-level light therapy (LLLT), since it utilizes light at a low power (0.1 to 0.5 W output at the source) to avoid any heating of tissue. The irradiance of the PBM medical devices (or power density) typically ranges from 1 to 10 times the NIR irradiance from sunlight on the skin (33.6  mW/cm2" role="presentation">33.6mW/cm2

at the zenith). However, most PBM medical devices only deliver light energy at one or two selected wavelengths, as opposed to the whole spectrum of IR that is contained in sunlight. To our knowledge and to this date, transcranial PBM treatment has not caused any retinal injury—one of the most likely postulated adverse events, although care is taken routinely in such studies to protect the eyes with goggles or eye covers.28

In this review, we will first discuss the mechanisms of action by which NIR and red light (PBM) might improve symptoms of depression, and then present the clinical evidence for their use as a treatment for MDD and other comorbid psychiatric syndromes.



We found clinical and preclinical studies via PubMed search (December 15, 2015), using the following keywords: “near-infrared radiation,” “NIR,” “low-level light therapy,” “low-level laser therapy,” or “LLLT” plus “depression.” We chose studies that had a clinical focus, and we excluded studies involving NIR spectroscopy. We also located studies using the references from the articles found in the PubMed search. As the searched literature encompassed different conditions and disorders frequently comorbid with depression, a specific section of this review was devoted to the effect of PBM on psychiatric comorbidity. In the latter section, the following conditions were included, based on available literature: TBI, anxiety and post-traumatic stress syndromes, insomnia, and suicidal ideation. The literature search for the use of PBM to treat comorbid conditions was neither systematic nor extensive, but rather a secondary focus of this review. The information is presented in an organized fashion to allow the reader to easily grasp the potential applications of PBM for the treatment of depression and of its comorbid conditions. To attain this goal, the authors have allowed a margin of redundancy, by distributing different information derived from any given publication in separate sections of this review. To avoid an artificial inflation of the extant literature on the chosen topic, we referenced the main authors—and when appropriate their affiliation—when referring to the same articles more than once. The reader will find a table summarizing the six key clinical articles reviewed, also to avoid unintended inflation of the literature. The six clinical reports included in this review where extracted from a pool of 58 articles, that were originally identified with the literature search.

In addition, we used PubMed to find articles that examined the link between PBM and each of the various biological processes including metabolism, inflammation, oxidative stress, and neurogenesis.


Targeting Brain Metabolism

Multiple studies have reported regional and global hypometabolism in MDD, which could be related (either causally or consequentially) to the neurobiology of mood disorders.2930.31.32 Positron emission tomography studies have shown abnormalities in glucose consumption rates and in blood flow in several brain regions of subjects with major depression.33 Moreover, metabolic abnormalities in the anterior cingulate, the amygdala-hippocampus complex, the dorsolateral prefrontal cortex (DLPFC), and inferior parietal cortex seem to improve after antidepressant treatment or after recovery.3435.36

With phosphorus magnetic resonance spectroscopy (P31-MRS" role="presentation">31P-MRS

), the baseline pool of nucleotide triphosphate (NTP)—a product of the cellular utilization of glucose and a marker of the cellular energy availability—was low in subjects who subsequently responded to antidepressant treatment.32 Iosifescu et al.32 also demonstrated for the first time with P31-MRS" role="presentation">31P-MRS a correlation between treatment response (to a regimen that combined antidepressants and triiodothyronine) and restoration of a higher NTP pool (with compensatory decrease in phosphocreatine) in the anterior cingulate cortex. This study suggests a pathway to antidepressant response based on restoration of a high cellular energy state. In fact, phosphocreatine represents a long-term storage depot of energy, while NTP and ATP are energy-rich molecules that are readily available to the cell. The same authors replicated the aforementioned findings in MDD subjects treated with standard antidepressants (Iosifescu et al., unpublished). In this cohort, P31-MRS" role="presentation">31P-MRS

metabolite changes were noted in brain-only voxels of responders, but not in nonresponders to antidepressants.

In experimental and animal models, PBM (NIR and red light) noninvasively delivers energy to the cytochrome c oxidase and by stimulating the mitochondrial respiratory chain leads to increased ATP production (see Fig. 1).3738.39 A study of the effects of NIR on patients with MDD found that a single session of NIR led to a marginally significant increase in regional cerebral blood flow.40 Whether the observed changes in cerebral blood flow resulted from fundamental changes in neuronal metabolism or changes in vascular tone remain to be clarified. Given the correlation of both hypometabolism and abnormal cerebral blood flow with MDD, the beneficial effect of NIR on brain metabolism is one potential mechanism for its antidepressant effect.

Fig. 1

Cellular targets of NIR radiation mechanisms of transcranial NIR for psychiatric disease. The NIR photons are absorbed by cytochrome c oxidase in the mitochondrial respiratory chain. This mitochondrial stimulation increases production of ATP but also activates signaling pathways by a brief burst of ROS. This signaling activates antioxidant defenses reducing overall oxidative stress. Proinflammatory cytokines and neuroinflammation are reduced. Neurotrophins such as brain-derived neurotrophic factor are upregulated, which in turn activate synaptogenesis (formation of new connections between existing neurons) and neurogenesis (formation of new neurons from neural stem cells).



Targeting Inflammation

Animal and clinical research suggests that the inflammatory arm of the immune system contributes to MDD. Post-mortem gene expression profiling on tissue samples from Brodmann area 10 (BA10—prefrontal cortex) have shown that MDD is characterized by increased inflammation and apoptosis.41 In a case-control study, Simon et al.42 found that antidepressant-naive MDD subjects had significant elevations in the following cytokines and chemokines when compared to healthy controls: MIP-1α" role="presentation">MIP-1α

, IL-1α" role="presentation">IL-1α, IL-1β" role="presentation">IL-1β, IL-6, IL-8, IL-10, Eotaxin, GM-CSF, and IFNγ" role="presentation">IFNγ

. Although IL-10 is an anti-inflammatory cytokine, the results suggested that the elevated levels of this IL-10 were likely induced in response to the overall elevation of proinflammatory cytokine levels. In a review of the research on inflammation in MDD, Raison et al.43 proposed that proinflammatory cytokines might cause brain abnormalities that are characteristic of MDD. Indeed, animal research has shown that IL-1 mediates chronic depression in mice by suppressing hippocampal neurogenesis.44

One proinflammatory cytokine that may be of particular relevance to depression is CSF IL-6 (IL6 measured in cerebrospinal fluid). In a recent report, patients with MDD had significantly higher CSF IL-6 levels compared to healthy controls; CSF IL-6 levels were significantly higher than in the serum, and there was no significant correlation between CSF and serum IL-6 levels.45 These findings are consistent with a prior report showing a positive correlation between CSF IL-6 levels and the severity of depression and suicide attempts, with the strongest correlation found in violent suicide attempters.46 One report in a smaller sample of depressed patients has shown that CSF IL-647 was lower or comparable to healthy controls.

NIR light and red light (600 to 1600 nm) decreased synovial IL-6 gene expression (decreased mRNA levels) in a rat model of rheumatoid arthritis.48 In another study, NIR (810 nm) used as a treatment for pain in patients with rheumatoid arthritis decreased production of the following proinflammatory cytokines: TNF-α" role="presentation">TNF-α

, IL-1β" role="presentation">IL-1β

, and IL-8.49 Khuman et al.50 showed that transcranial NIR improved cognitive function and reduced neuroinflammation as measured by Iba1+ activated microglia in brain sections from mice that had suffered a TBI. Finally, NIR (970 nm) has been found to be an effective treatment for inflammatory-type acne.51 In summary, it is reasonable to predict that transcranial NIR treatment would likewise have an anti-inflammatory effect in patients suffering from MDD.


Targeting Oxidative Stress

Research has demonstrated a correlation between MDD and vulnerability to oxidative stress.52 For example, depression-induced rats show a significant decrease in glutathione peroxidase (GSH-Px) activity in the cortex.53 Glutathione (GSH) is the most abundant and one of the important antioxidants in the brain; GSH-Px enzymes protect against oxidative stress via reducing hydroperoxides and scavenging free radicals.54 GSH also appears reduced in the brains of MDD subjects.55 Additionally, a study by Sarandol et al.52 demonstrated that MDD patients have higher levels of malondialdehyde, a toxic molecule and a biomarker of oxidative stress.56 Moreover, depressed patients have more red blood cell (RBC) oxidation compared to healthy controls.52 In the same study, the authors found a significant positive correlation between RBC superoxide dismutase (SOD) activity and depression severity. SOD serves to catalyze the removal of the toxic superoxide radical.57 Thus, elevated SOD activity in depressed patients might indicate higher levels of oxidative stress. Finally, catalase activity and nitric oxide (NO) levels have also been shown to be lower in depressed patients than in healthy controls.58 Catalase is an enzyme that protects cells against damaging reactive oxygen species (ROS) via degradation of hydrogen peroxide to water and oxygen.59 NO has protective effects against cell damage, which are likely due to its pleiotropic functions in regulating antioxidant enzymes and many other aspects of cell metabolism.60,61

Oxidative stress may be an effective target for antidepressant treatments. However, successful treatments for MDD vary in regard to their protective effects against oxidative stress.52,53,62 Animal research suggests that PBM may have beneficial effects on oxidative stress. In a rat model of traumatized muscle, NIR (904 nm) blocked the release of harmful ROS and the activation of the transcription factor, nuclear factor κB (NF-κB), both induced by muscle trauma. Trauma activates NF-κB by destroying a specific protein inhibitor of NF-κB called IκB, and this destruction was inhibited by NIR light. Furthermore, NIR reduced the associated overexpression of the inducible form of nitric oxide synthase (iNOS) and reduced the production of collagen.63 This regulation of iNOS is important because excessive levels of iNOS can lead to formation of large amounts of NO that combine with superoxide radicals to form the damaging species peroxynitrite, and can interfere with the protective benefits of other forms of NO synthase.64 These findings suggest that NIR protects against oxidative stress induced by trauma. Finally, an in vitro study of the effects of red light and NIR (700 to 2000 nm) on human RBCs found that NIR significantly protected RBCs against oxidation.65

Original Source:

Shining light on the head: Photobiomodulation for brain disorders

Michael R. Hamblin - 10.1016/j.bbacli.2016.09.002 (Publication)
This is 27 pages of independent analysis of how photobiomodulation effects the brain. Covers wavelengths, dosage, depths and underlying reactions. Amazing.
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Photobiomodulation (PBM) describes the use of red or near-infrared light to stimulate, heal, regenerate, and protect tissue that has either been injured, is degenerating, or else is at risk of dying. One of the organ systems of the human body that is most necessary to life, and whose optimum functioning is most worried about by humankind in general, is the brain. The brain suffers from many different disorders that can be classified into three broad groupings: traumatic events (stroke, traumatic brain injury, and global ischemia), degenerative diseases (dementia, Alzheimer's and Parkinson's), and psychiatric disorders (depression, anxiety, post traumatic stress disorder). There is some evidence that all these seemingly diverse conditions can be beneficially affected by applying light to the head. There is even the possibility that PBM could be used for cognitive enhancement in normal healthy people. In this transcranial PBM (tPBM) application, near-infrared (NIR) light is often applied to the forehead because of the better penetration (no hair, longer wavelength). Some workers have used lasers, but recently the introduction of inexpensive light emitting diode (LED) arrays has allowed the development of light emitting helmets or “brain caps”. This review will cover the mechanisms of action of photobiomodulation to the brain, and summarize some of the key pre-clinical studies and clinical trials that have been undertaken for diverse brain disorders.

Keywords: Photobiomodulation, Low level laser (light) therapy, Ischemic stroke, Traumatic brain injury, Alzheimer's disease, Parkinson's disease, Major depression, Cognitive enhancement

Graphical abstract

Image 2

1. Introduction

Photobiomodulation (PBM) as it is known today (the beneficial health benefits of light therapy had been known for some time before), was accidently discovered in 1967, when Endre Mester from Hungary attempted to repeat an experiment recently published by McGuff in Boston, USA [1]. McGuff had used a beam from the recently discovered ruby laser [2], to destroy a cancerous tumor that had been experimentally implanted into a laboratory rat. However (unbeknownst to Mester) the ruby laser that had been built for him, was only a tiny fraction of the power of the laser that had previously been used by McGuff. However, instead of curing the experimental tumors with his low-powered laser, Mester succeeded in stimulating hair regrowth and wound healing in the rats, in the sites where the tumors had been implanted [3], [4]. This discovery led to a series of papers describing what Mester called “laser biostimulation”, and soon became known as “low level laser therapy” (LLLT) [5], [6], [7].

LLLT was initially primarily studied for stimulation of wound healing, and reduction of pain and inflammation in various orthopedic conditions such as tendonitis, neck pain, and carpal tunnel syndrome [8]. The advent of light emitting diodes (LED) led to LLLT being renamed as “low level light therapy”, as it became more accepted that the use of coherent lasers was not absolutely necessary, and a second renaming occurred recently [9] when the term PBM was adopted due to uncertainties in the exact meaning of “low level”.

2. Mechanisms of action of photobiomodulation

2.1. Mitochondria and cytochrome c oxidase

The most well studied mechanism of action of PBM centers around cytochrome c oxidase (CCO), which is unit four of the mitochondrial respiratory chain, responsible for the final reduction of oxygen to water using the electrons generated from glucose metabolism [10]. The theory is that CCO enzyme activity may be inhibited by nitric oxide (NO) (especially in hypoxic or damaged cells). This inhibitory NO can be dissociated by photons of light that are absorbed by CCO (which contains two heme and two copper centers with different absorption spectra) [11]. These absorption peaks are mainly in the red (600–700 nm) and near-infrared (760–940 nm) spectral regions. When NO is dissociated, the mitochondrial membrane potential is increased, more oxygen is consumed, more glucose is metabolized and more ATP is produced by the mitochondria.

2.2. Reactive oxygen species, nitric oxide, blood flow

It has been shown that there is a brief increase in reactive oxygen species (ROS) produced in the mitochondria when they absorb the photons delivered during PBM. The idea is that this burst of ROS may trigger some mitochondrial signaling pathways leading to cytoprotective, anti-oxidant and anti-apoptotic effects in the cells [12]. The NO that is released by photodissociation acts as a vasodilator as well as a dilator of lymphatic flow. Moreover NO is also a potent signaling molecule and can activate a number of beneficial cellular pathways [13]. Fig. 2 illustrates these mechanisms.

Fig. 2
Tissue specific processes that occur after PBM and benefit a range of brain disorders. BDNF, brain-derived neurotrophic factor; LLLT, low level light therapy; NGF, nerve growth factor; NT-3, neurotrophin 3; PBM, photobiomodulation; SOD, superoxide dismutase. ...

2.3. Light sensitive ion channels and calcium

It is quite clear that there must be some other type of photoacceptor, in addition to CCO, as is clearly demonstrated by the fact that wavelengths substantially longer than the red/NIR wavelengths discussed above, can also produce beneficial effects is some biological scenarios. Wavelengths such as 980 nm [14], [15], 1064 nm laser [16], and 1072 nm LED [17], and even broad band IR light [18] have all been reported to carry out PBM type effects. Although the photoacceptor for these wavelengths has by no means been conclusively identified, the leading hypothesis is that it is primarily water (perhaps nanostructured water) located in heat or light sensitive ion channels. Clear changes in intracellular calcium can be observed, that could be explained by light-mediated opening of calcium ion channels, such as members of the transient receptor potential (TRP) super-family [19]. TRP describes a large family of ion channels typified by TRPV1, recently identified as the biological receptor for capsaicin (the active ingredient in hot chili peppers) [20]. The biological roles of TRP channels are multifarious, but many TRP channels are involved in heat sensing and thermoregulation [21].

2.4. Signaling mediators and activation of transcription factors

Most authors suggest that the beneficial effects of tPBM on the brain can be explained by increases in cerebral blood flow, greater oxygen availability and oxygen consumption, improved ATP production and mitochondrial activity [22], [23], [24]. However there are many reports that a brief exposure to light (especially in the case of experimental animals that have suffered some kind of acute injury or traumatic insult) can have effects lasting days, weeks or even months [25]. This long-lasting effect of light can only be explained by activation of signaling pathways and transcription factors that cause changes in protein expression that last for some considerable time. The effects of PBM on stimulating mitochondrial activity and blood flow is of itself, unlikely to explain long-lasting effects. A recent review listed no less than fourteen different transcription factors and signaling mediators, that have been reported to be activated after light exposure [10].

Fig. 1 illustrates two of the most important molecular photoreceptors or chromophores (cytochrome c oxidase and heat-gated ion channels) inside neuronal cells that absorb photons that penetrate into the brain. The signaling pathways and activation of transcription factors lead to the eventual effects of PBM in the brain.

Fig. 1
Molecular and intracellular mechanisms of transcranial low level laser (light) or photobiomodulation. AP1, activator protein 1; ATP, adenosine triphosphate; Ca2 +, calcium ions; cAMP, cyclic adenosine monophosphate; NF-kB, nuclear factor kappa ...

Fig. 2 illustrates some more tissue specific mechanisms that lead on from the initial photon absorption effects explained in Fig. 1. A wide variety of processes can occur that can benefit a correspondingly wide range of brain disorders. These processes can be divided into short-term stimulation (ATP, blood flow, lymphatic flow, cerebral oxygenation, less edema). Another group of processes center around neuroprotection (upregulation of anti-apoptotic proteins, less excitotoxity, more antioxidants, less inflammation). Finally a group of processes that can be grouped under “help the brain to repair itself” (neurotrophins, neurogenesis and synaptogenesis).

2.5. Biphasic dose response and effect of coherence

The biphasic dose response (otherwise known as hormesis, and reviewed extensively by Calabrese et al. [26]) is a fundamental biological law describing how different biological systems can be activated or stimulated by low doses of any physical insult or chemical substance, no matter how toxic or damaging this insult may be in large doses. The most well studied example of hormesis is that of ionizing radiation, where protective mechanisms are induced by very low exposures, that can not only protect against subsequent large doses of ionizing radiation, but can even have beneficial effects against diseases such as cancer using whole body irradiation [27].

There are many reports of PBM following a biphasic dose response (sometimes called obeying the Arndt-Schulz curve [28], [29]. A low dose of light is beneficial, but raising the dose produces progressively less benefit until eventually a damaging effect can be produced at very high light [30]. It is often said in this context that “more does not mean more”.

Another question that arises in the field of PBM is whether the coherent monochromatic lasers that were used in the original discovery of the effect, and whose use continued for many years, are superior to the rather recent introduction of LEDs, that are non-coherent and have a wider band-spread (generally 30 nm full-width half-maximum). Although there are one or two authors who continue to believe that coherent lasers are superior [31], most commentators feel that other parameters such as wavelength, power density, energy density and total energy are the most important determinants of efficacy [8].

3. Tissue optics, direct versus systemic effects, light sources

3.1. Light penetration into the brain

Due to the growing interest in PBM of the brain, several tissue optics laboratories have investigated the penetration of light of different wavelengths through the scalp and the skull, and to what depths into the brain this light can penetrate. This is an intriguing question to consider, because at present it is unclear exactly what threshold of power density in mW/cm2 is required in the b5rain to have a biological effect. There clearly must be a minimum value below which the light can be delivered for an infinite time without doing anything, but whether this is in the region of μW/cm2 or mW/cm2 is unknown at present.

Functional near-infrared spectroscopy (fNIRS) using 700–900 nm light has been established as a brain imaging technique that can be compared to functional magnetic resonance imaging (fMRI) [32]. Haeussinger et al. estimated that the mean penetration depth (5% remaining intensity) of NIR light through the scalp and skull was 23:6 + 0:7 mm [33]. Other studies have found comparable results with variations depending on the precise location on the head and wavelength [34], [35].

Jagdeo et al. [36] used human cadaver heads (skull with intact soft tissue) to measure penetration of 830 nm light, and found that penetration depended on the anatomical region of the skull (0.9% at the temporal region, 2.1% at the frontal region, and 11.7% at the occipital region). Red light (633 nm) hardly penetrated at all. Tedord et al. [37] also used human cadaver heads to compare penetration of 660 nm, 808 nm, and 940 nm light. They found that 808 nm light was best and could reach a depth in the brain of 40–50 mm. Lapchak et al. compared the transmission of 810 nm light through the skulls of four different species, and found mouse transmitted 40%, while for rat it was 21%, rabbit it was 11.3 and for human skulls it was only 4.2% [38]. Pitzschke and colleagues compared penetration of 670 nm and 810 nm light into the brain when delivered by a transcranial or a transphenoidal approach, and found that the best combination was 810 nm delivered transphenoidally [39]. In a subsequent study these authors compared the effects of storage and processing (frozen or formalin-fixed) on the tissue optical properties of rabbit heads [40]. Yaroslavsky et al. examined light penetration of different wavelengths through different parts of the brain tissue (white brain matter, gray brain matter, cerebellum, and brainstem tissues, pons, thalamus). Best penetration was found with wavelengths between 1000 and 1100 nm [41].

Henderson and Morries found that between 0.45% and 2.90% of 810 nm or 980 nm light penetrated through 3 cm of scalp, skull and brain tissue in ex vivo lamb heads [42].

3.2. Systemic effects

It is in fact very likely that the beneficial effects of PBM on the brain cannot be entirely explained by penetration of photons through the scalp and skull into the brain itself. There have been some studies that have explicitly addressed this exact issue. In a study of PBM for Parkinson's disease in a mouse model [43]. Mitrofanis and colleagues compared delivering light to the mouse head, and also covered up the head with aluminum foil so that they delivered light to the remainder of the mouse body. They found that there was a highly beneficial effect on neurocognitive behavior with irradiation to the head, but nevertheless there was also a statistically significant (although less pronounced benefit, referred to by these authors as an ‘abscopal effect”) when the head was shielded from light [44]. Moreover Oron and co-workers [45] have shown that delivering NIR light to the mouse tibia (using either surface illumination or a fiber optic) resulted in improvement in a transgenic mouse model of Alzheimer's disease (AD). Light was delivered weekly for 2 months, starting at 4 months of age (progressive stage of AD). They showed improved cognitive capacity and spatial learning, as compared to sham-treated AD mice. They proposed that the mechanism of this effect was to stimulate c-kit-positive mesenchymal stem cells (MSCs) in autologous bone marrow (BM) to enhance the capacity of MSCs to infiltrate the brain, and clear β-amyloid plaques [46]. It should be noted that the calvarial bone marrow of the skull contains substantial numbers of stem cells [47].

3.3. Laser acupuncture

Laser acupuncture is often used as an alternative or as an addition to traditional Chinese acupuncture using needles [48]. Many of the applications of laser acupuncture have been for conditions that affect the brain [49] such as Alzheimer's disease [50] and autism [51] that have all been investigated in animal models. Moreover laser acupuncture has been tested clinically [52].

3.4. Light sources

A wide array of different light sources (lasers and LEDs) have been employed for tPBM. One of the most controversial questions which remains to be conclusively settled, is whether a coherent monochromatic laser is superior to non-coherent LEDs typically having a 30 nm band-pass (full width half maximum). Although wavelengths in the NIR region (800–1100 nm) have been the most often used, red wavelengths have sometimes been used either alone, or in combination with NIR. Power levels have also varied markedly from Class IV lasers with total power outputs in the region of 10 W [53], to lasers with more modest power levels (circa 1 W). LEDs can also have widely varying total power levels depending on the size of the array and the number and power of the individual diodes. Power densities can also vary quite substantially from the Photothera laser [54] and other class IV lasers , which required active cooling (~ 700 mW/cm2) to LEDs in the region of 10–30 mW/cm2.

3.5. Usefulness of animal models when testing tPBM for brain disorders

One question that is always asked in biomedical research, is how closely do the laboratory models of disease (which are usually mice or rats) mimic the human disease for which new treatments are being sought? This is no less critical a question when the areas being studied include brain disorders and neurology. There now exist a plethora of transgenic mouse models of neurological disease [55], [56]. However in the present case, where the proposed treatment is almost completely free of any safety concerns, or any reported adverse side effects, it can be validly questioned as to why the use of laboratory animal models should be encouraged. Animal models undoubtedly have disadvantages such as failure to replicate all the biological pathways found in human disease, difficulty in accurately measuring varied forms of cognitive performance, small size of mice and rats compared to humans, short lifespan affecting the development of age related diseases, and lack of lifestyle factors that adversely affect human diseases. Nevertheless, small animal models are less expensive, and require much less time and effort to obtain results than human clinical trials, so it is likely they will continue to be used to test tPBM for the foreseeable future.

4. PBM for stroke

4.1. Animal models

Perhaps the most well-investigated application of PBM to the brain, lies in its possible use as a treatment for acute stroke [57]. Animal models such as rats and rabbits, were first used as laboratory models, and these animals had experimental strokes induced by a variety of methods and were then treated with light (usually 810 nm laser) within 24 h of stroke onset [58]. In these studies intervention by tLLLT within 24 h had meaningful beneficial effects. For the rat models, stroke was induced by middle cerebral artery occlusion (MCAO) via an insertion of a filament into the carotid artery or via craniotomy [59], [60]. Stroke induction in the “rabbit small clot embolic model” (RSCEM) was by injection of a preparation of small blood clots (made from blood taken from a second donor rabbit) into a catheter placed in the right internal carotid artery [61]. These studies and the treatments and results are listed in Table 1.

Table 1
Reports of transcranial LLLT used for stroke in animal models.

CW, continuous wave; LLLT, low level light therapy; MCAO, middle cerebral artery occlusion; NOS, nitric oxide synthase; RSCEM, rabbit small clot embolic model; TGFβ1, transforming growth factor β1.

4.2. Clinical trials for acute stroke

Treatment of acute stroke was addressed in a series of three clinical trials called “Neurothera Effectiveness and Safety Trials” (NEST-1 [65], NEST-2 [66], and NEST-3 [67]) using an 810 nm laser applied to the shaved head within 24 h of patients suffering an ischemic stroke. The first study, NEST-1, enrolled 120 patients between the ages of 40 to 85 years of age with a diagnosis of ischemic stroke involving a neurological deficit that could be measured. The purpose of this first clinical trial was to demonstrate the safety and effectiveness of laser therapy for stroke within 24 h [65]. tPBM significantly improved outcome in human stroke patients, when applied at ~ 18 h post-stroke, over the entire surface of the head (20 points in the 10/20 EEG system) regardless of stroke [65]. Only one laser treatment was administered, and 5 days later, there was significantly greater improvement in the Real- but not in the Sham-treated group (p < 0.05, NIH Stroke Severity Scale). This significantly greater improvement was still present at 90 days post-stroke, where 70% of the patients treated with Real-LLLT had a successful outcome, while only 51% of Sham-controls did. The second clinical trial, NEST-2, enrolled 660 patients, aged 40 to 90, who were randomly assigned to one of two groups (331 to LLLT, 327 to sham) [68]. Beneficial results (p < 0.04) were found for the moderate and moderate-severe (but not for the severe) stroke patients, who received the Real laser protocol [68]. These results suggested that the overall severity of the individual stroke should be taken into consideration in future studies, and very severe patients are unlikely to recover with any kind of treatment. The last clinical trial, NEST-3, was planned for 1000 patients enrolled. Patients in this study were not to receive tissue plasminogen activator, but the study was prematurely terminated by the DSMB for futility (an expected lack of statistical significance) [67]. NEST-1 was considered successful, even though as a phase 1 trial, it was not designed to show efficacy. NEST-2 was partially successful when the patients were stratified, to exclude very severe strokes or strokes deep within the brain [66]. There has been considerable discussion in the scientific literature on precisely why the NEST-3 trial failed [69]. Many commentators have wondered how could tPBM work so well in the first trial, in a sub-group in the second trial, and fail in the third trial. Lapchak's opinion is that the much thicker skull of humans compared to that of the other animals discussed above (mouse, rat and rabbit), meant that therapeutically effective amounts of light were unlikely to reach the brain [69]. Moreover the time between the occurrence of a stroke and initiation of the PBMT may be an important factor. There are reports in the literature that neuroprotection must be administered as soon as possible after a stroke [70], [71]. Furthermore, stroke trials in particular should adhere to the RIGOR (rigorous research) guidelines and STAIR (stroke therapy academic industry roundtable) criteria [72]. Other contributory causes to the failure of NEST-3 may have been included the decision to use only one single tPBM treatment, instead of a series of treatments. Moreover, the optimum brain areas to be treated in acute stroke remain to be determined. It is possible that certain areas of the brain that have sustained ischemic damage should be preferentially illuminated and not others.

4.3. Chronic stroke

Somewhat surprisingly, there have not as yet been many trials of PBM for rehabilitation of stroke patients with only the occasional report to date. Naeser reported in an abstract the use of tPBM to treat chronic aphasia in post-stroke patients [73]. Boonswang et al. [74] reported a single patient case in which PBM was used in conjunction with physical therapy to rehabilitate chronic stroke damage. However the findings that PBM can stimulate synaptogenesis in mice with TBI, does suggest that tPBM may have particular benefits in rehabilitation of stroke patients. Norman Doidge, in Toronto, Canada has described the use of PBM as a component of a neuroplasticity approach to rehabilitate chronic stroke patients [75].

5. PBM for traumatic brain injury (TBI)

5.1. Mouse and rat models

There have been a number of studies looking at the effects of PBM in animal models of TBI. Oron's group was the first [76] to demonstrate that a single exposure of the mouse head to a NIR laser (808 nm) a few hours after creation of a TBI lesion could improve neurological performance and reduce the size of the brain lesion. A weight-drop device was used to induce a closed-head injury in the mice. An 808 nm diode laser with two energy densities (1.2–2.4 J/cm2 over 2 min of irradiation with 10 and 20 mW/cm2) was delivered to the head 4 h after TBI was induced. Neurobehavioral function was assessed by the neurological severity score (NSS). There were no significant difference in NSS between the power densities (10 vs 20 mW/cm2) or significant differentiation between the control and laser treated group at early time points (24 and 48 h) post TBI. However, there was a significant improvement (27% lower NSS score) in the PBM group at times of 5 days to 4 weeks. The laser treated group also showed a smaller loss of cortical tissue than the sham group [76].

Hamblin's laboratory then went on (in a series of papers [76]) to show that 810 nm laser (and 660 nm laser) could benefit experimental TBI both in a closed head weight drop model [77], and also in controlled cortical impact model in mice [25]. Wu et al. [77] explored the effect that varying the laser wavelengths of LLLT had on closed-head TBI in mice. Mice were randomly assigned to LLLT treated group or to sham group as a control. Closed-head injury (CHI) was induced via a weight drop apparatus. To analyze the severity of the TBI, the neurological severity score (NSS) was measured and recorded. The injured mice were then treated with varying wavelengths of laser (665, 730, 810 or 980 nm) at an energy level of 36 J/cm2 at 4 h directed onto the scalp. The 665 nm and 810 nm groups showed significant improvement in NSS when compared to the control group at day 5 to day 28. Results are shown in Fig. 3. Conversely, the 730 and 980 nm groups did not show a significant improvement in NSS and these wavelengths did not produce similar beneficial effects as in the 665 nm and 810 nm LLLT groups [77]. The tissue chromophore cytochrome c oxidase (CCO) is proposed to be responsible for the underlying mechanism that produces the many PBM effects that are the byproduct of LLLT. COO has absorption bands around 665 nm and 810 nm while it has low absorption bands at the wavelength of 730 nm [78]. It should be noted that this particular study found that the 980 nm did not produce the same positive effects as the 665 nm and 810 nm wavelengths did; nevertheless previous studies did find that the 980 nm wavelength was an active one for LLLT. Wu et al. proposed that these dissimilar results may be due to the variance in the energy level, irradiance, etc. between the other studies and this particular study [77].

Fig. 3
tPBM for TBI in a mouse model. Mice received a closed head injury and 4 hours later a single exposure of the head to one of four different lasers (36 J/cm2 delivered at 150 mW/cm2 over 4 min with spot size 1-cm diameter) ...

Ando et al. [25] used the 810 nm wavelength laser parameters from the previous study and varied the pulse modes of the laser in a mouse model of TBI. These modes consisted of either pulsed wave at 10 Hz or at 100 Hz (50% duty cycle) or continuous wave laser. For the mice, TBI was induced with a controlled cortical impact device via open craniotomy. A single treatment with an 810 nm Ga-Al-As diode laser with a power density of 50 mW/m2 and an energy density of 36 J/cm2 was given via tLLLT to the closed head in mice for a duration of 12 min at 4 h post CCI. At 48 h to 28 days post TBI, all laser treated groups had significant decreases in the measured neurological severity score (NSS) when compared to the control (Fig. 4A). Although all laser treated groups had similar NSS improvement rates up to day 7, the PW 10 Hz group began to show greater improvement beyond this point as seen in Fig. 4. At day 28, the forced swim test for depression and anxiety was used and showed a significant decrease in the immobility time for the PW 10 Hz group. In the tail suspension test which measures depression and anxiety, there was also a significant decrease in the immobility time at day 28, and this time also at day 1, in the PW 10 Hz group.

Fig. 4
tPBM for controlled cortical impact TBI in a mouse model. (A) Mice received a single exposure (810 nm laser, 36 J/cm2 delivered at 50 mW/cm2 over 12 min) [121]. (B) Mice received 3 daily exposures starting 4 h post-TBI ...

Studies using immunofluorescence of mouse brains showed that tPBM increased neuroprogenitor cells in the dentate gyrus (DG) and subventricular zone at 7 days after the treatment [79]. The neurotrophin called brain derived neurotrophic factor (BDNF) was also increased in the DG and SVZ at 7 days , while the marker (synapsin-1) for synaptogenesis and neuroplasticity was increased in the cortex at 28 days but not in the DG, SVZ or at 7 days [80] (Fig. 4B). Learning and memory as measured by the Morris water maze was also improved by tPBM [81]. Whalen's laboratory [82] and Whelan's laboratory [83] also successfully demonstrated therapeutic benefits of tPBM for TBI in mice and rats respectively.

Zhang et al. [84] showed that secondary brain injury occurred to a worse degree in mice that had been genetically engineered to lack “Immediate Early Response” gene X-1 (IEX-1) when exposed to a gentle head impact (this injury is thought to closely resemble mild TBI in humans). Exposing IEX-1 knockout mice to LLLT 4 h post injury, suppressed proinflammatory cytokine expression of interleukin (IL)-Iβ and IL-6, but upregulated TNF-α. The lack of IEX-1 decreased ATP production, but exposing the injured brain to LLLT elevated ATP production back to near normal levels.

Dong et al. [85] even further improved the beneficial effects of PBM on TBI in mice, by combining the treatment with metabolic substrates such as pyruvate and/or lactate. The goal was to even further improve mitochondrial function. This combinatorial treatment was able to reverse memory and learning deficits in TBI mice back to normal levels, as well as leaving the hippocampal region completely protected from tissue loss; a stark contrast to that found in control TBI mice that exhibited severe tissue loss from secondary brain injury.

5.2. TBI in humans

Margaret Naeser and collaborators have tested PBM in human subjects who had suffered TBI in the past [86]. Many sufferers from severe or even moderate TBI, have very long lasting and even life-changing sequelae (headaches, cognitive impairment, and difficulty sleeping) that prevent them working or living any kind or normal life. These individuals may have been high achievers before the accident that caused damage to their brain [87]. Initially Naeser published a report [88] describing two cases she treated with PBM applied to the forehead twice a week. A 500 mW continuous wave LED source (mixture of 660 nm red and 830 nm NIR LEDs) with a power density of 22.2 mW/cm2 (area of 22.48 cm2), was applied to the forehead for a typical duration of 10 min (13.3 J/cm2). In the first case study the patient reported that she could concentrate on tasks for a longer period of time (the time able to work at a computer increased from 30 min to 3 h). She had a better ability to remember what she read, decreased sensitivity when receiving haircuts in the spots where LLLT was applied, and improved mathematical skills after undergoing LLLT. The second patient had statistically significant improvements compared to prior neuropsychological tests after 9 months of treatment. The patient had a 2 standard deviation (SD) increase on tests of inhibition and inhibition accuracy (9th percentile to 63rd percentile on the Stroop test for executive function and a 1 SD increase on the Wechsler Memory scale test for the logical memory test (83rd percentile to 99th percentile) [89].

Naeser et al. then went on to report a case series of a further eleven patients [90]. This was an open protocol study that examined whether scalp application of red and near infrared (NIR) light could improve cognition in patients with chronic, mild traumatic brain injury (mTBI). This study had 11 participants ranging in age from 26 to 62 (6 males, 5 females) who suffered from persistent cognitive dysfunction after mTBI. The participants' injuries were caused by motor vehicle accidents, sports related events and for one participant, an improvised explosive device (IED) blast. tLLLT consisted of 18 sessions (Monday, Wednesday, and Friday for 6 weeks) and commenced anywhere from 10 months to 8 years post-TBI. A total of 11 LED clusters (5.25 cm in diameter, 500 mW, 22.2 mW/cm2, 13 J/cm2) were applied for about 10 min per session (5 or 6 LED placements per set, Set A and then Set B, in each session). Neuropsychological testing was performed pre-LED application and 1 week, 1 month and 2 months after the final treatment. Naeser and colleagues found that there was a significant positive linear trend observed for the Stroop Test for executive function, in trial 2 inhibition (p = 0.004); Stroop, trial 4 inhibition switching (p = 0.003); California Verbal Learning Test (CVLT)-II, total trials 1–5 (p = 0.003); CVLT-II, long delay free recall (p = 0.006). Improved sleep and fewer post-traumatic stress disorder (PTSD) symptoms, if present beforehand, were observed after treatment. Participants and family members also reported better social function and a better ability to perform interpersonal and occupational activities. Although these results were significant, further placebo-controlled studies will be needed to ensure the reliability of this these data [90].

Henderson and Morries [91] used a high-power NIR laser (10–15 W at 810 and 980 nm) applied to the head to treat a patient with moderate TBI. The patient received 20 NIR applications over a 2-month period. They carried out anatomical magnetic resonance imaging (MRI) and perfusion single-photon emission computed tomography (SPECT). The patient showed decreased depression, anxiety, headache, and insomnia, whereas cognition and quality of life improved, accompanied by changes in the SPECT imaging.

6. PBM for Alzheimer's disease (AD)

6.1. Animal models

There was a convincing study [92] carried out in an AβPP transgenic mouse of AD. tPBM (810 nm laser) was administered at different doses 3 times/week for 6 months starting at 3 months of age. The numbers of Aβ plaques were significantly reduced in the brain with administration of tPBM in a dose-dependent fashion. tPBM mitigated the behavioral effects seen with advanced amyloid deposition and reduced the expression of inflammatory markers in the transgenic mice. In addition, TLT showed an increase in ATP levels, mitochondrial function, and c-fos expression suggesting that there was an overall improvement in neurological function.

6.2. Humans

There has been a group of investigators in Northern England who have used a helmet built with 1072 nm LEDs to treat AD, but somewhat surprisingly no peer-reviewed publications have described this approach [93]. However a small pilot study (19 patients) that took the form of a randomized placebo-controlled trial investigated the effect of the Vielight Neuro system (see Fig. 5A) (a combination of tPBM and intranasal PBM) on patients with dementia and mild cognitive impairment [94]. This was a controlled single blind pilot study in humans to investigate the effects of PBM on memory and cognition. 19 participants with impaired memory/cognition were randomized into active and sham treatments over 12 weeks with a 4-week no-treatment follow-up period. They were assessed with MMSE and ADAS-cog scales. The protocol involved in-clinic use of a combined transcranial-intranasal PBM device; and at-home use of an intranasal-only PBM device and participants/ caregivers noted daily experiences in a journal. Active participants with moderate to severe impairment (MMSE scores 5–24) showed significant improvements (5-points MMSE score) after 12 weeks. There was also a significant improvement in ADAS-cog scores (see Fig. 5B). They also reported better sleep, fewer angry outbursts and decreased anxiety and wandering. Declines were noted during the 4-week no-treatment follow-up period. Participants with mild impairment to normal (MMSE scores of 25 to 30) in both the active and sham sub-groups showed improvements. No related adverse events were reported.

Fig. 5
tPBM for Alzheimer's disease. (A) Nineteen patients were randomized to receive real or sham tPBM (810 nm LED, 24.6 J/cm2 at 41 mW/cm2). (B) Significant decline in ADAS-cog (improved cognitive performance) in real but not sham (unpublished ...

An interesting paper from Russia [95] described the use of intravascular PBM to treat 89 patients with AD who received PBM (46 patients) or standard treatment with memantine and rivastigmine (43 patients). The PBM consisted of threading a fiber-optic through a cathéter in the fémoral artery and advancing it to the distal site of the anterior and middle cerebral arteries and delivering 20 mW of red laser for 20–40 min. The PBM group had improvement in cerebral microcirculation leading to permanent (from 1 to 7 years) reduction in dementia and cognitive recovery.

7. Parkinson's disease

The majority of studies on PBM for Parkinson's disease have been in animal models and have come from the laboratory of John Mitrofanis in Australia [96]. Two basic models of Parkinson's disease were used. The first employed administration of the small molecule (MPTP or 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine) to mice [97]. MPTP was discovered as an impurity in an illegal recreational drug to cause Parkinson's like symptoms (loss of substantia nigra cells) in young people who had taken this drug [98]. Mice were treated with tPBM (670-nm LED, 40 mW/cm2, 3.6 J/cm2) 15 min after each MPTP injection repeated 4 times over 30 h. There were significantly more (35%–45%) dopaminergic cells in the brains of the tPBM treated mice [97]. A subsequent study showed similar results in a chronic mouse model of MPTP-induced Parkinson's disease [99]. They repeated their studies in another mouse model of Parkinson's disease, the tau transgenic mouse strain (K3) that has a progressive degeneration of dopaminergic cells in the substantia nigra pars compacta (SNc) [100]. They went on to test a surgically implanted intracranial fiber designed to deliver either 670 nm LED (0.16 mW) or 670 nm laser (67 mW) into the lateral ventricle of the brain in MPTP-treated mice [101]. Both low power LED and high power laser were effective in preserving SNc cells, but the laser was considered to be unsuitable for long-term use (6 days) due to excessive heat production. As mentioned above, these authors also reported a protective effect of abscopal light exposure (head shielded) in this mouse model [43]. Recently this group has tested their implanted fiber approach in a model of Parkinson's disease in adult Macaque monkeys treated with MPTP [102]. Clinical evaluation of Parkinson's symptoms (posture, general activity, bradykinesia, and facial expression) in the monkeys were improved at low doses of light (24 J or 35 J) compared to high doses (125 J) [103].

The only clinical report of PBM for Parkinson's disease in humans was an abstract presented in 2010 [104]
Original Source:

Low-level light emitting diode therapy promotes long-term functional recovery after experimental stroke in mice

Hae In Lee, Sae-Won Lee, Nam Gyun Kim, Kyoung-Jun Park, Byung Tae Choi, Yong-Il Shin - Wiley Online Journal/ 02 May 2017 (Publication)
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We aimed to investigate the effects of low-level light emitting diode therapy (LED-T) on the long-term functional outcomes after cerebral ischemia, and the optimal timing of LED-T initiation for achieving suitable functional recovery. Focal cerebral ischemia was induced in mice via photothrombosis. These mice were assigned to a sham-operated (control), ischemic (vehicle), or LED-T group [initiation immediately (acute), 4?days (subacute) or 10?days (delayed) after ischemia, followed by once-daily treatment for 7?days]. Behavioral outcomes were assessed 21 and 28?days post-ischemia, and histopathological analysis was performed 28?days post-ischemia. The acute and subacute LED-T groups showed a significant improvement in motor function up to 28?days post-ischemia, although no brain atrophy recovery was noted. We observed proliferating cells (BrdU+) in the ischemic brain, and significant increases in BrdU+/GFAP+, BrdU+/DCX+, BrdU+/NeuN+, and CD31+ cells in the subacute LED-T group. However, the BrdU+/Iba?1+ cell count was reduced in the subacute LED-T group. Furthermore, the brain-derived neurotrophic factor (BDNF) was significantly upregulated in the subacute LED-T group. We concluded that LED-T administered during the subacute stage had a positive impact on the long-term functional outcome, probably via neuron and astrocyte proliferation, blood vessel reconstruction, and increased BDNF expression.



Stroke is one of the major causes of serious and long?term disability 1, and >50?% of stroke survivors develop hemiparesis 6?months after stroke 2. However, the single available treatment for cerebral ischemia is only effective when administered within 4.5?h after cerebral ischemia 3. Moreover, no effective neuroprotective approach has been established for cases after ischemic brain injuries. The extent of disability caused by the cerebral ischemia gradually increases with time, and hence, appropriate therapeutic interventions should be developed to recover brain tissue damage and function.

During the chronic stroke phase, neurorestorative treatments are designed to enhance brain remodeling and neuroplasticity. Neurorestoration following a stroke is achieved by enhancing neurogenesis and angiogenesis, which consequently promotes functional recovery 4. In particular, neurogenesis promotes plasticity, restores neuronal signals, and stimulates myelination 5. Angiogenesis increases blood flow and support to create a hospitable environment for resident brain cells 6. Furthermore, microvessels and neuroblasts mutually support each other through the release of neurotrophic factors and closely function to mediate brain remodeling processes by reducing neuronal degeneration, promoting neuronal plasticity 7, and modulating glial responses 8. Brain?derived neurotrophic factor (BDNF) plays an important role in neurogenesis, proliferation, and neuronal survival 9, 10. Hence, it is important to determine which therapeutic intervention is more effective in facilitating neurorestoration and functional recovery via neurogenesis, angiogenesis, and BDNF upregulation following brain damage.

Low?level light therapy (LLLT) is a promising modality for the treatment of various conditions, including stroke, myocardial infarction, spinal cord injury, degenerative disorders, and traumatic brain injury 11, 12. LLLT has been found to exert significant biological effects in cell cultures, as well as in?vivo, in animal models and in clinical settings 13. LLLT exerts potent anti?inflammatory, anti?edema, and pro?angiogenetic effects 14, 15, and can facilitate wound healing by stimulating the proliferation of dividing cells 11, 15. The beneficial effects of LLLT on new synaptic connections have been shown to contribute to neural repair processes during the reorganization of brain tissues 14, 16. We recently reported that light?emitting diode therapy (LED?T) exerts neuroprotective effects against acute brain injury after focal cerebral ischemia 17, 18. Pre?conditioning or immediate treatment with LED?T after an ischemic insult can be effective against acute brain injury by aiding in anti?inflammation, blood?brain barrier protection, and neuroprotection 17, 18.

Although the neuroprotective effects of LED?T against acute brain injury (termed as “short?term effects”) have been previously reported, the effects of LED?T against late ischemic brain injury (long?term effects) remain unclear. In the present study, we evaluated the effects of LED?T on long?term functional outcomes following cerebral ischemia, along with the optimal timing of LED?T initiation for functional recovery by using a photothrombotic cortical ischemic mouse model. We performed behavior tests and histopathological analyses to assess neurorepair and functional recovery, and examined the optimal therapeutic time window and mechanisms underlying the long?term functional outcomes with LED?T.

2 Materials and methods

2.1 Animals

All experiments were performed in accordance with the guidelines of the Pusan National University?Institutional Animal Care and Use Committee on ethical procedures and scientific care, following approval by the institutional review board of Pusan National University (approval number: PNU?2015?1041). Adult male C57BL/6J mice (6?weeks, 20–25?g) were housed under diurnal lighting conditions with free access to food and tap water, with a 12?h light/dark cycle. The mice were adapted to these conditions for at least 7?days prior to the experiments, and were then assigned to a specific group after collecting baseline measurements. The mice were assigned to the following 5?groups (Figure?1): control, sham?operated mice (n=14); vehicle, cerebral ischemia induction without LED?T (n=14); acute LED?T, mice that received LED?T immediately post?ischemia, followed by once?daily treatments for 7 consecutive days (n=14); subacute LED?T, mice that received LED?T 4 days post?ischemia, followed by once?daily treatments for 7 consecutive days (n=14); delayed LED?T, mice that received LED?T 10 days post?ischemia, followed by once?daily treatments for 7 consecutive days (n=14). Computer?generated randomization was conducted by SigmaPlot 11.2 (Systat Software Inc, San Jose, CA) for allocating to control, vehicle, acute LED?T, subacute LED?T or delayed LED?T groups. After getting the random number by computer?generated randomization, C57/BL6J male mice were allocated in a blinded fashion.

Experimental design and time line. (A) Baseline data were collected 1 day before cerebral ischemia induction in the sham, vehicle, and LED?T groups. The LED therapy group was further sub?divided into 3 groups (acute LED?T, subacute LED?T, and delayed LED?T), wherein LED?T was initiated at different time points and was continued for 7?days consecutively. Behavioral tests were conducted on days?21 and 28. On day?28, all the mice were sacrificed for histological examination. (B) After photothrombosis with illumination, the mice received LED?T for 7 consecutive days, although the therapy was initiated at different time points for the various therapy groups.


2.2 Experimental model of photothrombotic stroke

Focal cerebral ischemia was induced via photothrombosis, as previously described 17. Briefly, mice were anesthetized using face mask?delivered 2?% isoflurane, and were maintained on 1.5?% air with 80?% N2O and 20?% O2. For the surgery, the head of the mouse was fixed in a stereotactic frame (David Kopf Instruments, Tujunga, CA), and the bregma and lambda points were identified following a middle scalp incision. A photochemical dye, Rose Bengal (Sigma?Aldrich, St. Louis, MO), was administrated intraperitoneally (10?mg/ml in saline) 5?min prior to illumination. The exposed intact skull was then illuminated with a fiber optic bundle of a KL6000 LED cold light source (Carl Zeiss, Jena, Germany) using a micromanipulator for 15?min (Figure?1B). Thereafter, the surgical wound was sutured and the mice were allowed to recover.

2.3 Low?level light emitting diode therapy

Mice received treatment using a skin?adhesive LED light source (Color Seven Co., Seoul, Korea) as previously reported 18. For LED?T, a device with a peak wavelength of 610?nm (orange color) was placed on the skin at 2 concurrent locations on the head (the right midpoint of the parietal bone and the posterior midline of the seventh cervical vertebra) using double?sided tape (Figure?1B). The mice received treatment from the light source, which was set to 2.0?J/cm2 (1.7?mW/cm2×20?min), once a day for 7 consecutive days; the treatments commenced at different time points. The vehicle group was kept under isoflurane anesthesia without any LED treatment.

Effects of LED?T on behavioral function and brain atrophy. (A, B) Behavioral tests were conducted at different time points; before ischemia and day 21 and 28 post?ischemia. The wire?grip test (A) and rotarod test (B) were performed in all the groups (n=14 in each group). Data are expressed as mean±SEM. ###P<0.001 vs. the Control; *P<0.05, **P<0.01, ***P<0.001 vs. the Vehicle group. (C?E) Post?stroke brain atrophy was evaluated. (C) Quantitation of brain atrophy showed that there is no significant difference between the vehicle (Veh) and LED?T groups (n=4 in each group). #P<0.05 vs. the Control group. (D) Representative whole brain images after cerebral ischemia on day?28. (E) Image of H&E staining. Each region was located at 2.80?mm, 2.34?mm, and 1.98?mm from the bregma. Scale bar=1?cm.

2.4 Bromodeoxyuridine (BrdU) labeling

Bromodeoxyuridine (BrdU; Sigma?Aldrich, St. Louis, MO) was dissolved in 0.9?% saline and administered intraperitoneally (50?mg/kg). To analyze cell proliferation, all animals received BrdU injections once a day for 5 successive days after ischemia. On day 28 after cerebral ischemia, the animals were deeply anesthetized and transcardially perfused.

2.5 Behavior tests

A wire?grip test to evaluate vestibular motor function was conducted with the mouse placed on a metal wire (length: 45?cm) suspended across 2 upright poles (height: 45?cm). The mice were scored based on the manner in which they held onto the wire for 60?s and traversed the wire. The wire?grip score was quantified using a 5?point scale: grade 0, inability to remain on the wire for ≥30?s; grade?1, failure to hold on to the wire with the fore paws and hind paws together; grade?2, grasping of the wire with the fore and hind paws, but not the tail; grade?3, grasping of the wire using the tail, along with the fore and hind paws; and grade?4, movement along the wire on all 4 paws along with the tail. Rotarod test was performed by using a rotarod apparatus (Panlab S.L.U., Barcelona, Spain), in order to evaluate motor coordination and equilibrium. The rotarod speed was increased from 4 to 40?rpm during adaptation trials. After then, each mouse was placed on the rotating rod. Five trials were performed per day at a speed of 18?rpm for 3?min. The data are presented as the average of 5 recorded values.

2.6 Determination of brain atrophy

Brain atrophy was estimated via Hematoxylin and eosin (H&E) staining. In brief, mice were anesthetized with sodium thiopental, and perfused with cold PBS followed by 4?% paraformaldehyde (PFA), after which the brains were removed. Fixed brains were embedded in paraffin, serially sectioned (5?μm), and stained with H&E. The tissue slides were mounted in the mounting medium (Vector Laboratories, Burlingame, CA, USA). The areas of the contralateral and ipsilateral hemisphere were analyzed with the iSolution analysis software (Image & Microscope Technology, Vancouver, Canada).

2.7 Immunohistochemistry

Mice were anesthetized with sodium thiopental, perfused with cold PBS followed by 4 % PFA and the brains were removed. The brains further fixed in 4?% PFA at 4?°C for 24?h, followed by cryoprotection in 30?% sucrose for 72?h at 4?°C. Next, the isolated brains were frozen in an optical cutting temperature medium for frozen tissue specimens (Sakura Finetek, Torrance, CA) and stored at −80?°C until examined. The frozen brain sections (20?μm) were incubated with blocking buffer (1xPBS/5?% normal goat serum/0.3?% Triton X?100) for 1?h at room temperature. The specific primary antibodies were incubated overnight at 4?°C. BrdU (1:500; OBT0030GAbD, Serotec, Oxford, UK), GFAP (1:100; MAB360, Milipore Corporation, Billerica, MA, USA), Iba?1 (1:200; 019–19741, Wako, Pure Chemical Industries, Osaka, Japan), NeuN (1:500; MAB377, Milipore Corporation), doublecortin (DCX, 1:200; sc?8066, Santa Cruz Biotecnology, Santa Cruz, CA, USA), CD31 (1:100; 550274, BD Biosciences, San Jose, CA, USA), mBNDF (1:500; NB100?98682, Novus Biologicals, Littleton, CO). The sections were then incubated with fluorescent conjugated secondary antibodies (Thermo, Waltham, MA, USA) and DAPI (Invitrogen Corporation, Carlsbad, CA, USA) for 2?h at room temperature. Sequently, slides were washed and cover?slipped with mounting medium (Vector Laboratories, Inc). Titled images (0.36?mm2/field) of each section were capture with a laser scanning confocal microscope (Carl Zeiss, Inc., Jena, Germany) and morphological analysis and quantification of positive cells were countered using a iSolution analysis software (Image & Microscope Technology, Vancouver, Canada). Blood vessel staining with CD31 was measured as the integrated optical density (IOD) of CD31 positive cells. The IOD and counted cells were captured from 3?fields (0.36?mm2/field) per 3?predefined areas per adjacent 3?brain sections from each mouse were analyzed.

2.8 Statistical analysis

The data are expressed as the means ± SEM. Statistical comparisons were performed using the SigmaStat statistical program version 11.2 (Systat Software, SanJose, CA, USA). Data were analyzed statistically using one?way ANOVA or one?way repeated ANOVA followed by Student?Newman?Keuls test. A P<0.3 was considered statistically significant.

Effect of LED?T on astrocyte proliferation in cerebral ischemic cortex. (A) Immunofluorescence staining for BrdU (green) and GFAP (red) in the ipsilateral side of cerebral cortex at 28 days after ischemia. Scale bar=50 μm. (B) BrdU (green) and GFAP (red) in the subacute LED?T group. Scale bar=50 μm. (C) Quantitation of BrdU+ or BrdU+/GFAP+ cells in the cerebral cortex. The number of proliferating astrocytes, marked by BrdU+/GFAP+, was significantly greater in the subacute LED?T group (n=4 in each group). #P<0.05 vs. the Control; *P<0.05 vs. the Vehicle group.

3 Results

3.1 LED?T improves functional recovery after cerebral ischemia

In order to determine whether LED?T can promote functional recovery after cerebral ischemia, we examined the wire?grip test and rotarod tests 21?days and 28?days post?ischemia (Figure?2A and 2B). The wire?grip test for vestibular motor function indicated lower values in the vehicle group than in the control group, but higher values in the acute and subacute LED?T groups than in the vehicle group. In particular, the acute LED?T group showed a significant improvement at 21?and 28?days post?ischemia, whereas the subacute LED?T group showed a significant improvement at 28?days after cerebral ischemia (Figure?2A). The motor coordination observed on the rotarod test also showed a similar pattern (Figure?2B). The acute and subacute LED?T group indicated marked functional recovery at 21 and 28?days after cerebral ischemia (Figure?2B). We also measured the body weight of all mice during experiments, and we observed that the body weight between groups was not significantly altered (data not shown).

Effect of LED?T on microglial proliferation. (A, B) Immunofluorescence staining for BrdU (green) and Iba?1 (red) in the cerebral cortex of ipsilateral side in the subacute LED?T group at 28 days after ischemia. Scale bar=50 μm. (B) Enlarged view. Arrow; BrdU+/Iba?1+ cell. (C) Quantitation of BrdU+ or BrdU+/Iba?1+ cells in the cerebral cortex. The subacute LED?T group exhibited a significant decrease in the proliferating microglia, in comparison with the Vehicle group (n=4 in each group). ###P<0.001 vs. the Control; *P<0.05 vs. the Vehicle group.

Next, we evaluated whether post?stroke brain atrophy was affected by LED?T (Figure?2C–2E). At 28?days after cerebral ischemia, apparent atrophy in the ischemic cortex was observed on gross photographs of the whole brain and in brain sections stained with H&E. Moreover, we found that the ipsilateral volume was significantly reduced following brain injury, and that LED?T did not restore the lesion volume (Figure?2C–5E).

Effect of LED?T on neuronal cell proliferation. (A) Immunofluorescence staining for BrdU (green) and DCX (red) in the ipsilateral cerebral cortex in the subacute LED?T group. Scale bar=50 μm. (B) The number of BrdU+/DCX+ cells was greater in the subacute LED?T group (n=4 in each group). #P<0.05 vs. the Control; *P<0.05, ***P<0.001 vs. the Vehicle group.

3.2 LED?T regulates the proliferation of astrocytes and microglia after cerebral ischemia

To evaluate the effect of LED?T on the proliferation of glial cells, brain tissues (28?days post?ischemia) were stained for the astrocyte marker GFAP and microglia marker Iba?1 (Figure?3 and 4). BrdU+ cells were detected in the cerebral cortex, and the subacute LED?T group showed a significantly higher number of BrdU+ cells in the ipsilateral hemisphere than did the vehicle group. Moreover, the number of proliferating astrocytes (BrdU+/GFAP+ cells) was significantly greater in the vehicle group than in the control group, and these counts were even greater in the acute, subacute, and delayed LED?T groups (Figure?3C). With regard to the proliferation of microglia (BrdU+/Iba?1+ cells), the vehicle group exhibited a significantly higher number of BrdU+/Iba?1+ cells than did the control. In contrast, BrdU+/Iba?1+ cells were significantly lower in the subacute LED?T group than in the vehicle group at 28?days after cerebral ischemia (Figure?6).

Effect of LED?T on the number of NeuN+ cells after cerebral ischemia. (A) Immunofluorescence staining for BrdU (green) and NeuN (red) in the ipsilateral cerebral cortex. Scale bar=50 μm. (B) The number of mature neuron (Brdu+/NeuN+) cells was significantly greater following subacute LED?T treatment (n=4 in each group). #P<0.05 vs. the Control; **P<0.01 vs. the Vehicle group.

3.3 LED?T promotes the proliferation and differentiation of neuronal cells

To evaluate the influence of LED?T on the proliferation and differentiation of neuronal cells (Figure 5 and 6), we counted the BrdU+/DCX+ (an immature neuronal cell marker) and BrdU+/NeuN+ (a mature neuronal cell marker) cells in the cerebral cortex. We found that both BrdU+/DCX+ cells and BrdU+/NeuN+ cells were present in the ipsilateral cortex, and that the numbers of these cells were significantly greater in the subacute LED?T group than in the vehicle group. These results suggest that subacute LED?T can increase the number of newly formed neuroblasts and enhance their differentiation towards neurons.

Effect of LED?T on microvessels after cerebral ischemia. (A) Immunofluorescence staining for CD31 (an endothelial cell marker) with DAPI (blue) in the ipsilateral cerebral cortex. Scale bar=50 μm. (B) Enlarged view. (C) The integrated optical density (IOD) for CD31+ immunofluorescence was significantly greater after subacute LED?T (n=4 in each group). *P<0.05 vs. the Vehicle group.

3.4 LED?T promotes CD31?postive cells in cerebral ischemic cortex

To examine whether LED?T also affects the formation of blood vessels in the cerebral cortex after ischemia, we measured the levels of blood vessel with specific marker CD31 at the peri?infarct region (Figure?7A and B). The numbers of CD31+ cells were significantly greater in the subacute LED?T group than in the vehicle group, indicating that subacute LED?T can facilitate blood vessel reconstruction in the ischemic area (Figure?7C).

Effect of LED?T on the mBDNF expression after cerebral ischemia. (A) mBDNF expression (red) in the cerebral cortex of ipsilateral side in the subacute LED?T group on day 28 post?ischemia. Scale bar=50 μm. (B) Quantitative graph for the mBDNF+ cells (n=4 in each group). ###P<0.001 vs. the Control; *P<0.05 vs. the Vehicle group.

3.5 LED?T upregulates the BDNF level in the post–ischemic cerebral cortex

As the subacute LED?T group exhibited marked increases in proliferating neuronal cells, we examined whether LED?T could regulate the levels of BDNF, a well?known neurotrophic factor 10, in the cerebral cortex (Figure?8). We found a lower number of BDNF+ cells in the ipsilateral cortex in the vehicle group at 28?days post?ischemia, which was significantly increased following subacute LED?T.

4 Discussion

In this study undertaken to examine the effects of LED?T on long?term functional outcomes post?ischemia, we observed that, in addition to its known neuroprotective effects during the acute phase of experimental stroke, the initiation of LED?T during the subacute stage following cerebral ischemia has a positive impact on the long?term (28?days) functional outcome, and leads to the proliferation of neurons and astrocytes and facilitation of blood vessel reconstruction. In the present study, we showed that subacute LED?T enhances the expression of BDNF, which is known to be involved in the repair/plasticity processes 9, and could thus possibly mediate the above?mentioned effects.

In our study, we found that LED?T has a long?term protective effect against late cerebral injuries at 21 and 28?days after focal cerebral ischemia in mice, which has not been reported previously. Moreover, we have recently described that pre?conditioning or immediate treatment with LED?T after an ischemic insult exerts neuroprotective effects against acute brain injury following focal cerebral ischemia 17, 18. However, it is unclear whether these neuroprotective effects observed in acute phase experiments (1 day or 3 days post?ischemia) will persist in the chronic phase (28 days post?ischemia). Moreover, it is important to identify the therapeutic interventions that ameliorate the chronic responses secondary to the acute injury. We found that the acute and subacute LED?T groups had significantly improved motor function, whereas brain atrophy did not recover following LED?T (Figure?2).

Stroke recovery involves heterogeneous processes, and there are many factors, including brain structure, brain damage, and therapeutic intervention, that can affect the functional outcome 19, 20. Although structural damage was observed in the ipsilesional M1 of patients with subcortical stroke and significant motor recovery, the structurally impaired M1 region retained the potential for functional reorganization 21. Hence, the observation of the repair process, including the proliferation and differentiation of neurons and glia, as well as the reconstruction of blood vessels, in the ipsilateral lesion of the acute LED?T and subacute LED?T groups is vital, even though the structural damage remains unaffected by LED?T.

The efficacy of therapeutic interventions after stroke is time?dependent 22, 23. The interventions initiated 5 or 7 days after ischemic brain injury significantly improved the functional recovery and increased the structural plasticity; however, these beneficial effects were not observed in delayed rehabilitation initiated 30 days after stroke 24. We found that the acute and subacute LED?T groups had significantly improved motor functions, consistent with previous reports, whereas the delayed LED?T groups did not (Figure?2), thus indicating that the first 10 days after a stroke may represent a critical period during which the brain is most responsive to rehabilitation therapy. Moreover, it appeared that the delayed LED?T group did not yield a sufficient long?term outcome, and hence, the initiation of delayed?stage therapeutic interventions may limit functional recovery (Figure?2). Therefore, we suggest that the optimal timing of the initiation of LED?T is important for achieving suitable long?term outcomes, and that there may be positive effects on neurovascular remodeling during the subacute stage of cerebral ischemia, including long?term effects at the behavioral and structural level.

The role of reactive astrocytes after stroke remains controversial 25. The astrocytic inflammatory response to stroke aggravates the ischemic lesion during the acute phase 26. However, astrocyte activation, as evidenced by the astrocyte marker GFAP, may also contribute to functional recovery 27, 28. Astrocytes can support neurons by secreting neurotrophic factors 29, controlling brain homoeostasis, and creating a microenvironment for successful brain remodeling. Hence, reactive astrocytes may potentially play both detrimental and beneficial roles under certain temporal conditions after stroke. Furthermore, we found that the numbers of BrdU+/GFAP+ cells were significantly increased in the cerebral cortex in the acute, subacute, and delayed LED?T groups at 28?days post?ischemia (Figure?3). We have previously shown that pretreatment with LED?T markedly reduced the numbers of Iba?1? and GFAP?positive cells, as well as the levels of inflammatory mediators 24 h after cerebral ischemia 17. These results suggest that LED?T may have dual effects in attenuating inflammation via astrocyte count reduction during the acute phase and in promoting neural repair and functional recovery via astrocyte proliferation during the chronic phase after ischemic brain injury. Microglia are among the first cells to respond to brain damage and serve as potent modulators of repair and regeneration 30 by releasing destructive pro?inflammatory mediators. The subacute LED?T group exhibited significant suppression of BrdU+/Iba?1+ cells in comparison with the vehicle group (Figure?4), thus suggesting that the suppressive microgliosis induced by subacute LED?T may contribute to post?ischemic recovery.

During the recovery period after cerebral ischemia, we found that LED?T enhanced neurogenesis (Figure?5 and 6). Neurogenesis plays a pivotal role in the recovery from cerebral ischemia 5. In particular, we found that the subacute LED?T group had an increased number of BrdU+/DCX+ and BrdU+/NeuN+ cells, which suggests that LED?T may stimulate neurogenesis or play beneficial roles in brain repair (Figure?5 and 6). Similarly, angiogenesis, wherein vessels are newly formed from existing vessels, also contributes to recovery after cerebral ischemia 6. In the subacute LED?T group, the number of CD31+ cells increased in the cerebral cortex in comparison with that in the vehicle group (Figure?7). These findings indicate that subacute LED?T may facilitate new vessel formation during ischemic recovery. Thus, our results show strong evidence that neurovascular networks were remodeled by subacute LED?T.

Neuroprotection is associated with the BDNF level 10, and hence, we attempted to assess whether BDNF expression is involved in the effects of LED?T. BDNF is an attractive target in the molecular signaling pathways that regulate neuronal survival and dendritic growth during cerebral remodeling 9. BDNF modulates the dendritic structure and promotes the synaptic regulation and axonal plasticity associated with sensorimotor recovery 31. Greater BDNF expression was observed in the subacute LED?T group than in the vehicle group (Figure?8), which suggests that the upregulation of BDNF may represent an important step in the facilitation of brain repair by subacute LED?T.

In conclusion, our study helped identify the effects of LED?T during the subacute stage, as well as the underlying mechanisms, in an experimental animal model of ischemic stroke, particularly with regard to the improvements in the long?term functional outcome, through neuron and astrocyte proliferation, blood vessel reconstruction, and BDNF expression increase. Overall, these findings suggest that LED?T is a promising candidate as a neurorestorative therapy after stroke.


1D. Mukherjee, C. G. Patil, World Neurosurg 76, S85–90 (2011).


2M. Kelly-Hayes, A. Beiser, C.?S. Kase, A. Scaramucci, R.?B. D′Agostino, P.?A. Wolf, Journal of Stroke and Cerebrovascular Diseases: the Official Journal of National Stroke Association 12, 119–26 (2003).


3U. Dirnagl, C. Iadecola, M. A. Moskowitz, Trends in Neurosciences 22, 391–7 (1999).


4D. M. Hermann, M. Chopp, Lancet Neurology 11, 369–80 (2012).


5J. Chen, P. Venkat, A. Zacharek, M. Chopp, Frontiers in Human Neuroscience 8, 382 (2014).

Original Source:

Low level light emitting diode (LED) therapy suppresses inflammasome-mediated brain damage in experimental ischemic stroke

dHae In Lee Sae, Won Lee Nam Gyun Kim Kyoung Jun Park Byung Tae Choi Yong Shin Hwa Kyoung Shin - Wiley-VCH Verlag GmbH & Co. 06 February 2017 (Publication)
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Use of photostimulation including low?level light emitting diode (LED) therapy has broadened greatly in recent years because it is compact, portable, and easy to use. Here, the effects of photostimulation by LED (610 nm) therapy on ischemic brain damage was investigated in mice in which treatment started after a stroke in a clinically relevant setting. The mice underwent LED therapy (20 min) twice a day for 3 days, commencing at 4 hours post?ischemia. LED therapy group generated a significantly smaller infarct size and improvements in neurological function based on neurologic test score. LED therapy profoundly reduced neuroinflammatory responses including neutrophil infiltration and microglia activation in the ischemic cortex. LED therapy also decreased cell death and attenuated the NLRP3 inflammasome, in accordance with down?regulation of pro?inflammatory cytokines IL?1β and IL?18 in the ischemic brain. Moreover, the mice with post?ischemic LED therapy showed suppressed TLR?2 levels, MAPK signaling and NF?kB activation. These findings suggest that by suppressing the inflammasome, LED therapy can attenuate neuroinflammatory responses and tissue damage following ischemic stroke. Therapeutic interventions targeting the inflammasome via photostimulation with LED may be a novel approach to ameliorate brain injury following ischemic stroke.


Effect of post?ischemic low?level light emitting diode therapy (LED?T) on infarct reduction was mediated by inflammasome suppression.



Ischemic stroke, a cerebrovascular insult, is the most common cause of physical disabilities worldwide. However, the only FDA approved treatment is tissue plasminogen activator that must be administered up to 4.5 hours after stroke onset 1. Therefore, identifying new stroke therapeutics would address a significant unmet medical need. Ischemic stroke initiates a complex cascade of events that leads to focal brain damage, and in which inflammation plays a significant role 2. The inflammatory response includes activation of resident microglia and production of pro?inflammatory cytokines 3, followed rapidly by infiltration and accumulation of neutrophils and monocytes/macrophages in microvessels and ischemic cerebral parenchyma 4.

Inflammatory mechanisms that contribute to cell death in cerebral ischemia are mediated by a multi?protein complex called the inflammasome 5-9. The key component is NOD?like receptor pyridine domain?containing (NLRP) protein, which initiates inflammasome activation when bound by its ligand. More specifically, the NLRP1 and NLRP3 inflammasomes are cytosolic complexes containing NLRP1 or NLRP3 receptor protein, ASC (apoptosis?associated speck?like protein containing a caspase recruitment domain), X?linked inhibitor of apoptosis (XIAP), precursor caspase?1 and/or precursor caspase?11 10. First, toll?like receptors (TLRs) trigger mitogen activated protein kinase (MAPK) signaling pathways and nuclear factor kappa?B (NF?kB) activation, which regulate NLRP3 expression 11-13 and induce formation of the inflammasome. Its activation then cleaves pro?caspase?1 into the bioactive form, which then induces production of active IL?1β and IL?18; ultimately, this induces pyroptosis, a type of inflammatory cell death 5-9, 14, 15. Therefore, targeting components in the inflammasome pathways may offer a new therapeutic strategy for the treatment of ischemic stroke.

Recently low?level light therapy has gained attraction in treating neurological and psychological disorders because it is relatively cheap, non?invasive, and safe 16-20. Low?level light therapy has been used neurotherapeutically because it can penetrate the scalp and skull 21. In addition, low?level light therapy can modulate a wide range of cellular processes via absorption of light energy via chromophores or photoreceptors in the mitochondria 22. The photochemistry hypothesis is a widely accepted to explain the induction of photobiological effects such as increasing energy in the form of ATP, generating reactive oxygen species (ROS) and nitric oxide, and modification of intracellular organelle membrane activity; these then lead to activation of downstream signaling pathways and transcription factors 23, 24. Transcranial near?infrared light therapy was shown to reduce ischemic brain damage in rabbit acute ischemic stroke 25. Light therapy (710 nm) showed neuroprotection in rat experimental stroke models 26, 27, and has shown clinical promise when tissue regeneration and prevention of tissue damage are required 23. Furthermore, low?level laser light (800 nm) improves cognitive deficits and modulates neuroinflammation after traumatic brain injury 28, 29, and low?level laser therapy (632.8 nm) suppresses microglia activation in BV2 microglial cells 29.

While the use of low?level light therapy mostly involves red and near?infrared light, low?power light emitting diode (LED) using visible light is attractive because LEDs are safer, generating negligible heat at the targeted tissue surface. In addition, LEDs are more affordable, compact/portable, and easier to use. Therefore, we investigated whether acute LED therapy using visible light (orange; 610 nm; see Figure 1 for details on the apparatus) could suppress ischemic brain damage in a focal cerebral ischemia mouse model, using clinically relevant post?stroke parameters.

Experimental scheme of the low?level light emitting diode (LED) therapy. (A) The technical characteristics of the skin?adherent low?level light emitting diode probe. (B) The mice underwent LED therapy (20 min) twice a day for 3 days commencing at 4 h post?ischemia. The control group was kept under isoflurane anesthesia for 20 min without LED application.

Materials and methods

General surgical preparation

All animal experiments were conducted in accordance with the guidelines of the Pusan National University?Institutional Animal Care and Use Committee (PNU?IACUC) on their ethical procedures and scientific care, and were approved by the PNU?IACUC in Pusan National University (Approval Number PNU?2014?0646). Male mice (C57BL/6J, 20–25 g) were housed under diurnal lighting conditions and allowed food and tap water ad libitum. Anesthesia was achieved by face mask?delivered isoflurane (2% induction and 1.5% maintenance, in 80% N2O and 20% O2). Rectal temperature was maintained at 36.5–37.5 °C using a Panlab thermostatically controlled heating mat (Harvard Apparatus, Holliston, MA).

Low?level light emitting diodes (LED) therapy

A skin?adherent LED probe (Color Seven Co., Seoul, Korea) was used for LED therapy with the following technical characteristics: peak wavelength, 610 nm (orange color); power intensity, 1.7 mW/cm2; energy density, 2.0 J/cm2 (Figure 1A). Light stimulation was applied by placing the probes (spot size, 4?mm diameter) onto the skin via double?sided tape at two locations on the head (the right midpoint of the parietal bone and the posterior midline of the seventh cervical vertebra) concurrently (Figure 1B). The mice underwent LED therapy (20 min) twice a day for 3 days, commencing at 4 h after the ischemic insult. The control group was kept under isoflurane anesthesia for 20 min without LED (Figure 1B). Experimental drugs including a TLR2 agonist (Pam2CSK4; 50 µg/kg, Invivogen, San Diego, CA) 30, NLRP3 agonist (MSU crystals; 10 mg/kg, Invivogen) 31, and NLRP3 antagonist (MCC950; 10 mg/kg, Sigma, St. Louis, MO) 32 were intraperitoneally administered to mice 30 min before LED therapy. Control mice were administered PBS.

Focal cerebral ischemia

Focal cerebral ischemia was induced by photothrombosis of the cortical microvessels 33. The advantages of this model are simple animal preparation, no craniotomy or mechanical manipulation of cerebral blood vessels or parenchyma, and easily reproducible lesion size and location. Briefly, photochemical dye Rose Bengal (Sigma?Aldrich, St. Louis, MO; 0.1 ml of a 10 mg/ml solution in sterile saline) was injected intraperitoneally so that it entered the blood stream 5 min before illumination. When brain is illuminated by a Cold?light source CL 6000 LED (Carl Zeiss, Jena, Germany), the dye becomes activated and induces endothelial damage with platelet activation and thrombosis, resulting in local blood flow interruption 34. The mice were placed in a stereotaxic frame (David Kopf Instruments, Tujunga, CA) for illumination, the skull was exposed, and bregma and lambda identified. A fiber optic bundle of a cold light source with a 4 mm aperture was centered 2.4 mm laterally from the bregma using a micromanipulator located over the sensorimotor cortex. The brain was illuminated for 15 min, the surgical wound was sutured, and the mice were allowed to recover from anesthesia (Figure 1B).

Infarct volume

Mice were deeply anesthetized with sodium thiopental 72 h after ischemic insults, and the brains were removed. The cerebral infarct size was determined on 2,3,5?triphenyltetrazolium chloride (TTC)?stained, 2?mm?thick brain sections. Infarction areas were quantified using the iSolution full image analysis software (Image & Microscope Technology, Vancouver, Canada). To account for and eliminate the effects of swelling/edema, the infarction volume was calculated using an indirect measurement in which the volumes of each section were summed according to the following formula: contralateral hemisphere (mm3) – undamaged ipsilateral hemisphere (mm3).

Neurological score

Neurological deficit was scored in each mouse at 72 h after ischemic insult in a blinded fashion according to the following graded scoring system: 0 = no deficit; 1 = forelimb weakness and torso turning to the ipsilateral side when held by the tail; 2 = circling to the affected side; 3 = unable to bear weight on the affected side; and 4 = no spontaneous locomotor activity or barrel rolling 35.

Western blotting

Mice were deeply anesthetized with sodium thiopental 72 h after the induction of ischemia, and then perfused transcardially with cold PBS. Brain cortices were subsequently collected and total protein was isolated according to the standard methods. Samples were separated by 12% sodium dodecyl sulfate?polyacrylamide gel electrophoresis, and transferred onto a polyvinylidene difluoride (PVDF) membrane (Amersham Biosciences, Piscataway, NJ). Immunoblot analysis was performed with the specific primary antibodies followed by secondary antibody conjugated with horseradish peroxidase: TLR?2 (1 : 1000; sc?16237), TLR?4 (1 : 1000; sc?293072), NF?κB p65 (1 : 1000; sc?109), ASC (1 : 1000; sc?22514?R), precursor IL?1β (1 : 500; sc?7884), mature IL?1β (1 : 500, sc?7884), precursor IL?18 (1 : 500; sc?7954), mature IL?18 (1 : 500; sc?7954, Santa Cruz Biotechnology, Dallas, TX), p38 (1 : 1000; 9212S), p?p38 (1 : 1000; 9212S), JNK (1 : 1000; 9251S), p?JNK (1 : 1000; 9251S), ERK (1 : 1000; 4695), p?ERK (1 : 1000; 4695, Cell signaling, Danvers, MA), NLRP1 (1 : 1000; NBP1?54899), NLRP3 (1 : 1000; NBP1?77080), XIAP (1 : 1000; NB100?56183), cleaved caspase?1 (1 : 500; NBP1?45433), pro?caspase?1 (1 : 500; NBP1?45433), cleaved caspase?11 (1 : 500; NBP1?45453), pro?caspase?11 (1 : 500; NBP1?45453, Novus Biologicals, Littleton, CO), myeloperoxidase (MPO, 1 : 1000; af3667, R&D systems, Minneapolis, MN). The intensity of chemiluminescence was measured using an ImageQuant LAS 4000 apparatus (GE Healthcare Life Sciences, Uppsala, Sweden). The membrane was then stripped and incubated with anti?β?actin (1 : 2000; A5316, Sigma) or anti?Lamin B (1 : 1000; sc?3740, Santa Cruz Biotechnology) antibodies as an internal control.

TUNEL analysis and PI staining

Neuronal death was evaluated by TUNEL analysis and propidium iodide (PI) staining. Mice were perfused transcardially with cold PBS prior to processing of tissue. The frozen brains were cut to a thickness of 8 μm using a CM 3050 cryostat (Leica Microsystems, Wetzlar, Germany), and the TUNEL assay was performed using a DeadEndTM Fluorometric TUNEL System kit (Promega Corporation, Madison, WI). For PI staining, brain sections were incubated with PI (50 μg/ml). After mounting using a fluorescent mounting medium (Vector Laboratories, Inc., Burlingame, CA), images were obtained with a fluorescence microscope (Axio Imager M1, Carl Zeiss). TUNEL(+)/PI(+) cells were counted blindly from three fields per three predefined areas per three adjacent brain sections from each mouse.

Immunohistochemical staining

Seventy two hours after focal cerebral ischemia, mice were deeply anesthetized with sodium thiopental and subsequently perfused transcardially with cold PBS followed by 4% paraformaldehyde for fixation. Each mouse brain was removed and further fixed in 4% paraformaldehyde at 4 °C for 24 h, followed by cryoprotection in 30% sucrose for 72 h at 4 °C. Next, the isolated brains were frozen in an optimal cutting temperature medium for frozen tissue specimens (Sakura Finetek, Torrance, CA) and stored at –80 °C until examined. The frozen brains were cut to a thickness of 14 μm using a CM 3050 cryostat (Leica Microsystems), and the sections were pretreated with 0.1% H2O2 for 20 min, incubated with blocking buffer (CAS block; Invitrogen Corporation, Carlsbad, CA), and subsequently incubated with primary antibodies against Iba?1 (1 : 200; 019?19741, Wako, Pure Chemical Industries, Osaka, Japan) at 4 °C overnight. The sections were then incubated with biotinylated secondary antibody (1 : 500; BA?1000, Vector Laboratories, Inc.) for 2 h. After several washing, sections were incubated in an avidin?biotinylated peroxidase complex (ABC) reagent (Vectastain ABC kit, Vector Laboratories Inc.) and visualized using a diaminobenzidine (DAB) solution (Vector Laboratories Inc.). All samples were visualized using a light microscope (Carl Zeiss, Jena, Germany). For immunofluorescence staining, the brain sections were immunostained with primary antibodies against MPO (1 : 300; af3667, R&D systems), Iba?1 (1 : 200; 019?19741, Wako, Pure Chemical Industries) or CD68 (1 : 500; MCA1957GA, AbD Serotec, Oxford, UK) at 4 °C overnight. The samples were incubated with FITC? (1 : 500; FI?1000, FI?5000) or Texas Red?conjugated secondary antibodies (1 : 500; TI?9400, Vector Laboratories, Inc.) for 2 h in the dark. The images of each section were captured with a fluorescence microscope (Axio Imager M1, Carl Zeiss) and morphological analysis and quantification of positive cells was conducted using the iSolution analysis software (Image & Microscope Technology). For quantification of positive cells, at least three randomly selected fields (0.36 mm2/field) in the peri?infarct area were examined and averaged. The MPO(+) or Iba?1(+)/CD68(+) cells from three fields per three adjacent brain sections from each mouse were counted.

Data analysis

Quantification of band intensity was performed by Image J software (NIH, Bethesda, MD, USA) and normalized to the intensity of internal control. Data are expressed as the means ± the SEM. Differences between two groups were determined using the unpaired t?test; and comparing more than two groups was determined by one?way analysis of variance (ANOVA) followed by Student?Newman?Keuls test. A P < 0.05 was considered statistically significant.


LED therapy reduced brain damage when administered after stroke onset

We first evaluated whether post?ischemic treatment with LED therapy could improve tissue and functional outcomes following focal cerebral ischemia (Figures 1 and 2). As shown in Figure 2A, TTC staining revealed that LED therapy significantly reduced infarct volume relative to controls when measured 72 h after ischemic brain injury (37.0 ± 5.0 mm3 vs. 58.0 ± 7.0 mm3, LED therapy and control, respectively, P < 0.05; Figure 2A and B). Thus, acute LED therapy treatment reduces the spread of ischemic damage. As with infarct volume, ischemia?induced neurological deficits were significantly attenuated in the LED?treated mice (P < 0.05; Figure 2C and Supplementary file), as measured by a scored evaluation of neurologic function (a lower score represents less deficit; see Supplementary file). Together, these findings indicated that acute post?ischemic LED therapy improved tissue?level markers of ischemic damage, and neurological function, in a focal cerebral ischemic mouse model.

Post?ischemic LED therapy improved tissue and functional outcome in a mouse model of ischemic stroke. (A, B) LED therapy (LED?T) reduced infarct volume compared with the control mice (Con). At 72 h after photothrombotic cortical ischemia, brains were removed and brain sections were sequentially obtained. Coronal brain sections (2?mm?thick) were stained with 2,3,5?triphenyltetrazolium chloride (TTC). White indicates the infarct area (A). Quantification of the infarct volume (B) was analyzed using the iSolution full image analysis software (N = 9, * P < 0.05 vs. control group). (C) LED therapy improved neurologic function after cerebral ischemia. Neurological deficit was evaluated 72 h after cerebral ischemia in a blinded fashion followed by neurological score (0 means no deficit. The lower score represents less deficit). Data are expressed as the means ± SEM (N = 9). * P < 0.05 when compared with the control group (Con).

LED therapy attenuated post?ischemic neuroinflammatory responses

We investigated whether LED therapy modulated ischemia?related neuroinflammation by immunofluorescence staining and western blotting for myeloperoxidase (MPO; Figure 3A–D), a marker of neutrophil infiltration. MPO demonstrated fewer neutrophils in the cortical region after LED treatment (P < 0.01; Figure 3B and C). Western blotting revealed that LED therapy significantly reduced MPO protein levels compared to the control group (P < 0.01; Figure 3D). We next examined microglial activation in the ischemic cortex using Iba?1 (marker protein expressed in both quiescent and active microglia) 36, 37 and CD68 (active microglia marker) 37 using immunohistochemial staining (Figure 3E–G). Iba?1/CD68 double positive cells indicated the active microglia. Iba?1(+)/CD68(+) cells in the ischemic cortex were significantly decreased in the LED therapy group relative to the control group (P < 0.05; Figure 3E and F). Morphology of Iba?1(+) microglia could be more clearly observed in Figure 3G. LED therapy remarkably reduced the Iba?1 immunoreactivies in the penumbra region of the cerebral cortex (Figure 3G). These findings suggest that neuroinflammation such as neutrophil infiltration and microglia activation after ischemic brain injury was effectively rescued by LED therapy.

Treatment with LED therapy reduced neuroinflammatory responses after ischemic stroke. (A) The coronal section illustrates the infarct region (grey) and the red rectangle indicates the imaging field. (B) LED therapy (LED?T) reduced neutrophil infiltration. Immunofluorescence staining for MPO (green), a marker for neutrophil infiltration, in control and LED?treated mouse brains 72 h after focal cerebral ischemia. (Scale bar = 100 μm). (C) Quantification graph of MPO(+) cells. (D) Western blot using ipsilateral protein showed that LED therapy decreased the expression of MPO in ischemic brain (top). The quantification graph of MPO immunoblots is shown (bottom, N = 3, ** P < 0.01 vs. control group). (E) Immunofluorescence staining for activated microglial marker Iba?1 (green) and CD68 (red) in the ischemic cortex. Fewer Iba?1(+)/CD68(+) cells (yellow) were observed in the LED therapy group. Scale bar = 100 μm. (F) Quantification graph of Iba?1(+)/CD68(+) cells. Data are expressed as the means ± SEM (N = 4). * P < 0.05 when compared with the control group (Con). (G) Iba?1 immunoreactivities were decreased in the penumbra region of the cerebral cortex with LED therapy. Magnification = ×100. The scale bar = 50 µm.

LED therapy attenuated neural cell death and inflammasome activity after ischemic brain injury

We further evaluated the effects of LED treatment on neural cell death after focal cerebral ischemia (Figures 4A and 4B). Fewer TUNEL(+)/PI(+) cells (apoptotic cells) were observed in the ischemic cortex of the LED therapy group (P < 0.05; Figure 4A and B). We next examined the effects of LED therapy on levels of inflammasome components in brain tissue ipsilateral to the lesion 72 h after ischemic insult. (Figure 4C). NLRP3 was significantly decreased in the LED therapy group relative to the control group (P < 0.05; Figure 4C). Moreover, LED therapy significantly reduced the levels of cleaved caspase?1 and ?11 (Figure 4D), as well as mature IL?1β and IL?18 in ischemic brain tissue (Figure 4E).

Post?ischemic treatment of LED therapy promoted neural cell survival in ischemic stroke through inflammasome suppression. (A) Representative photomicrographs for TUNEL (green) and PI (red). Fewer TUNEL(+)/PI(+) cells were observed in the LED therapy group (LED?T). Scale bar = 100 μm. (B) Quantification graph of TUNEL(+)/PI(+) cells in the ischemic cortex. Data are expressed as the means ± SEM (N = 4). * P < 0.05 when compared with the control group (Con). (CE) Post?ischemic LED treatment decreases NLRP3 expression and inflammasome activity in ipsilateral side after ischemic stroke. (C) Among inflammasome component proteins such as NLRP1, NLRP3, ASC and XIAP, LED therapy decreases the level of NLRP3 (left). Quantification graph of immunoblots (right, N = 5, * P < 0.05 vs. control). (D, E) The level of activated inflammasome proteins such as cleaved?caspase?1 and cleaved?caspase?11 and maturation of IL?1β and IL?18 was investigated in ipsilateral brain tissues of C57BL/6J mice following focal cerebral ischemia. Data are expressed as the means ± SEM (N = 4 or 5). * P < 0.05, ** P < 0.01 when compared with the control group (Con).

The LED therapeutic effect on infarct reduction was mediated by NLRP3 in vivo. NLRP3 antagonist (MCC950; 10 mg/kg) or NLRP3 agonist (MSU crystals; 10 mg/kg) was administered intraperitoneally injection to mice 30 min before LED therapy. (A) After photothrombotic cortical ischemia, coronal brain sections (2 mm?thick) were stained with TTC. Blue triangle indicates the infarct area. (B) Quantification of the infarct volume was analyzed (N = 5 ∼ 7 each, means ± SEM). * P < 0.05 vs. control group (Con), ## P < 0.01, when compared with the LED?T group (one?way ANOVA). (C) LED treatment attenuates ischemic brain damage via reduction of NLRP3 level. MCC950 alone, NLRP3 inhibitor, reduced ischemic brain damage. In contrast, MSU crystal (NLRP3 agonist) blocks the LED?T effect on brain damage reduction.

We next investigated whether NLRP3 mediated the in vivo reduction of infarct volume described above (Figure 5). As seen in Figure 5, monotherapy with MCC950, a potent inhibitor of NLRP3 32 reduced infarct volume to sizes similar to LED therapy (Figure 5A and B), although the effect was not statistically significant. In contrast, an NLRP3 agonist (MSU crystals) 31 combined with LED therapy significantly inhibited the reductive effect of LED therapy effect on infarct volume (P < 0.01) (Figure 5A–C). These results indicate that post?ischemic LED therapy decreased ischemic brain damage, possibly by NLRP3?mediated inflammasome suppression.

Post?ischemic LED therapy reduced TLR?2 and triggered MAP kinase (MAPK) and NF?kB inactivation

Activation of TLRs primes NLRP3?mediated inflammasome activation, and thus cell death 38, 39, therefore, we determined expression levels of TLR?2 and TLR?4 (Figure 6A). TLR2 and TLR4 stimulation lead to priming of NLRP3 40, 41. LED therapy significantly reduced TLR?2, but not TLR?4, protein levels in the ischemic cortex (Figure 6A). We also examined MAPKs and NF?kB (Figure 6B and C) protein, as these are components of the TLR pathways. LED therapy significantly attenuated the levels of p?JNK and p?ERK, and significantly reduced translocation of the NF?κB p65 protein subunit into the nucleus, relative to the control group (P < 0.05; Figure 6B and C). These data suggest that LED therapy is capable of decreasing TLR?2?mediated signaling induced by ischemic insult.

Post?ischemic LED treatment reduced TLR?2 expression, phosphorylation of MAPKs, and NF?κB activation in a mouse ischemic stroke model. (A) TLR?2 expression in ipsilateral brain tissues was reduced in LED therapy group (LED?T). N = 5, * P < 0.05 vs. control group (Con). (B) Levels of phosphorylated p38, JNK and ERK in ipsilateral brain tissues of C57BL/6J mice following focal cerebral ischemia. LED therapy suppressed the phospho?JNK and phospho?ERK (N = 5, * P < 0.05 vs. Con). (C) Western blot analysis using ipsilateral brain tissues shows that nuclear localization of NF?kB was decreased by LED treatment. Data are expressed as the means ± SEM (N = 5, * P < 0.05 vs. Con).

Finally, we analyzed whether in vivo infarct volume reduction by LED therapy was mediated by TLR2 (Figure 7). LED therapy significantly reduced infarct volume compared to controls, but when co?treated with the TLR2 agonist Pam2CSK4 30 and LED therapy, the reduction in infarct volume was significantly inhibited (P < 0.001) (Figure 7B). These findings suggested that TLR2 mediated post?ischemic improvements by LED therapy.

Infarct volume reduction by LED therapy was mediated by TLR2 in vivo. TLR2 agonist (Pam2CSK4; 50 µg/kg) was administered intraperitoneal injection to mice 30 min before LED therapy. (A) Representative photographs of coronal brain section with TTC staining. Blue triangle indicates the infarct area. (B) Quantification of the infarct volume was analyzed (N = 5 each, means ± SEM). ** P < 0.01 vs. control group (Con), ### P < 0.001, when compared with the LED?T group (one?way ANOVA). (C) LED treatment attenuates ischemic brain damage via reduction of TLR2 level. Pam2CSK4, TLR2 agonist, blocks the LED effect.


These studies determined that post?ischemic LED therapy reduced infarct volume in a focal cerebral ischemia mouse model. We found that LED therapy suppressed neuroinflammation and neural cell death in the ischemic cortex via TLR2?mediated activation and the NLRP3 inflammasome; and that this activation was in turn mediated through MAPK and NF?kB pathways (Figure 8). Notably, we also found improvement in neurological scores after LED therapy.

Schematic model for neuroprotection by LED therapy after ischemic stroke injury.

Interest in low?level light therapy is rapidly growing as new data on its effects are reported 21. Previous reports have demonstrated benefits including rescue of cognitive impairment and other deficits associated with chronic neurological conditions 16-20. Low?level light therapy (633 nm and 870 nm together) has improved cognition in patients with traumatic brain injury 17. Low?level light therapy also improved memory in normal adult rats 19 and middle?aged mice 42. It has been reported that near?infrared light therapy decreases depression in human subjects 16 and improves locomotor activity in rats with traumatic brain injury 18 and mice with Parkinson's disease 20. Moreover, low?level light therapy using near?infrared has reduced ischemic brain damage in experimentally induced stroke in rabbits 25, and showed neuroprotection effect in experimental stroke of rats 26, 27. It was previously reported that low?level light therapy is also effective in a pre?conditioning mode on pain, heart attack, wound healing, central nervous system and so on 43. We recently reported the preventive effect of LED therapy on ischemic brain injury of mouse 44. Since low?level light therapy is economical and has few side effects, it is applicable for clinical prevention, and not just the treatment of the cerebral ischemic disease. While the low?level light therapy mostly focused on red and near?infrared, we are interested in using low?power LED with visible light because LED using visible light are more affordable, compact/portable, and easier to use. Our results were obtained using LED therapy (610 nm orange light) applied twice a day for 3 days, commencing at 4 h after the ischemic event (Figure 2, Supplementary File), and observed the underlying mechanisms of ischemic damage reduction.

For application of light therapy, longer red/near?infrared wavelengths are much better at penetrating tissue than shorter blue/green wavelengths, therefore red and near?infrared lights are preferred clinically. There are few studies to evaluate the transmission rate of radiation in the skull 45, 46. Radiation (emitted in the 600–800 nm spectrum) can penetrate about 1 cm into the skull of human cadavers 45. Jagdeo et al. observed that 600–800 nm radiation range can penetrate soft tissues, bone, and brain parenchyma in cadavers preserved in formalin 46. Although we can suggest the penetration possibility of 610 nm light into human skull from these reports, but we don't know exactly whether our LED parameters are experimentally arrived at the target sites in human. Further investigation needed to clarify this issue.

Ischemic stroke initiates a complex cascade of pathogenetic events that lead to focal brain damage, and inflammation is a major contributor 2. Abulafia et al. 5 described a novel inflammatory mechanism through which the inflammasome contributes to neuronal cell death in cerebral ischemia 5. NLRP3 is known for its role in inflammasome formation, creating multi?protein complexes with ASC and XIAP that are critical for caspase?1 and ?11 activation, and subsequent active IL?1β/IL?18 production 10. During cerebral ischemic injury, there is increased expression of inflammasome components such as NLRP1, NLRP3, ASC, and pro?caspase?1 and ?11 5. While most innate signaling receptors have a relatively restricted ligand spectrum, NLRP3 can be activated by diverse entities such as infectious microorganisms, microbial products, dying cell fragments, and small molecule immune activators 47, 48. It has been suggested that the major role of NLRP3 inflammasomes is in
Original Source:

Rehabilitative Paradigms after Experimental Brain Injury: Relevance to Human Neurotrauma.

EditorsIn: Kobeissy FH, editor. - AuthorsBondi CO, Tehranian-DePasquale R, Cheng JP, Monaco CM, Griesbach GS, Kline AE. (Publication)
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Intro: The goal of this chapter is to describe four relatively non-invasive rehabilitative paradigms that may have clinical relevance following brain injury. Specifically, the benefits and limitations of environmental enrichment, exercise, low-level laser therapy, and constraint-induced movement therapy will be discussed. Timing issues (e.g., best time to initiate treatment as well as duration of treatment) and the advantage of adjunct therapies (i.e., can they further improve functional outcome) will also be discussed. Overall, the literature suggests that each of the aforementioned therapies confer significant behavioral improvement after experimental brain trauma. Hence, we propose that they should be considered for implementation in clinical rehabilitation.

Background: The goal of this chapter is to describe four relatively non-invasive rehabilitative paradigms that may have clinical relevance following brain injury. Specifically, the benefits and limitations of environmental enrichment, exercise, low-level laser therapy, and constraint-induced movement therapy will be discussed. Timing issues (e.g., best time to initiate treatment as well as duration of treatment) and the advantage of adjunct therapies (i.e., can they further improve functional outcome) will also be discussed. Overall, the literature suggests that each of the aforementioned therapies confer significant behavioral improvement after experimental brain trauma. Hence, we propose that they should be considered for implementation in clinical rehabilitation.

Abstract: Excerpt The goal of this chapter is to describe four relatively non-invasive rehabilitative paradigms that may have clinical relevance following brain injury. Specifically, the benefits and limitations of environmental enrichment, exercise, low-level laser therapy, and constraint-induced movement therapy will be discussed. Timing issues (e.g., best time to initiate treatment as well as duration of treatment) and the advantage of adjunct therapies (i.e., can they further improve functional outcome) will also be discussed. Overall, the literature suggests that each of the aforementioned therapies confer significant behavioral improvement after experimental brain trauma. Hence, we propose that they should be considered for implementation in clinical rehabilitation. © 2015 by Taylor & Francis Group, LLC.

Methods: © 2015 by Taylor & Francis Group, LLC.

Original Source:

Photobiomodulation Suppresses Alpha-Synuclein-Induced Toxicity in an AAV-Based Rat Genetic Model of Parkinson's Disease.

Oueslati A, Lovisa B, Perrin J, Wagnieres G, van den Bergh H, Tardy Y, Lashuel HA - (Publication)
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 Laboratory of Molecular and Chemical Biology of Neurodegeneration, Brain Mind Institute, Swiss Federal Institute of Technology (EPFL), CH-1015, Lausanne, Switzerland; Centre de Recherche du Centre Hospitalier de Quebec, Axe Neuroscience et Departement de Medecine Moleculaire de l'Universite Laval, Quebec, G1V4G2, Canada. Institute of Chemical Sciences and Engineering, Swiss Federal Institute of Technology (EPFL), CH-1015, Lausanne, Switzerland; Medos International Sarl, a Johnson&Johnson company, Chemin Blanc 38, CH-2400, Le Locle, Switzerland. Medos International Sarl. Qatar Biomedical Research Institute, Hamad Bin Khalifa University, Qatar Foundation, P.O. Box 5825, Doha, Qatar.

Converging lines of evidence indicate that near-infrared light treatment, also known as photobiomodulation (PBM), may exert beneficial effects and protect against cellular toxicity and degeneration in several animal models of human pathologies, including neurodegenerative disorders. In the present study, we report that chronic PMB treatment mitigates dopaminergic loss induced by unilateral overexpression of human alpha-synuclein (alpha-syn) in the substantia nigra of an AAV-based rat genetic model of Parkinson's disease (PD). In this model, daily exposure of both sides of the rat's head to 808-nm near-infrared light for 28 consecutive days alleviated alpha-syn-induced motor impairment, as assessed using the cylinder test. This treatment also significantly reduced dopaminergic neuronal loss in the injected substantia nigra and preserved dopaminergic fibers in the ipsilateral striatum. These beneficial effects were sustained for at least 6 weeks after discontinuing the treatment. Together, our data point to PBM as a possible therapeutic strategy for the treatment of PD and other related synucleinopathies.

PLoS One 2015 10(10) e0140880

Original Source:

Red and NIR light dosimetry in the human deep brain.

Pitzschke A, Lovisa B, Seydoux O, Zellweger M, Pfleiderer M, Tardy Y, Wagnieres G - (Publication)
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 Federal Institute of Technology (EPFL), Institute of Chemical Sciences and Engineering (ISIC), 1015 Lausanne, Switzerland.

Photobiomodulation (PBM) appears promising to treat the hallmarks of Parkinson's Disease (PD) in cellular or animal models. We measured light propagation in different areas of PD-relevant deep brain tissue during transcranial, transsphenoidal illumination (at 671 and 808 nm) of a cadaver head and modeled optical parameters of human brain tissue using Monte-Carlo simulations. Gray matter, white matter, cerebrospinal fluid, ventricles, thalamus, pons, cerebellum and skull bone were processed into a mesh of the skull (158 x 201 x 211 voxels; voxel side length: 1 mm). Optical parameters were optimized from simulated and measured fluence rate distributions. The estimated mueff for the different tissues was in all cases larger at 671 than at 808 nm, making latter a better choice for light delivery in the deep brain. Absolute values were comparable to those found in the literature or slightly smaller. The effective attenuation in the ventricles was considerably larger than literature values. Optimization yields a new set of optical parameters better reproducing the experimental data. A combination of PBM via the sphenoid sinus and oral cavity could be beneficial. A 20-fold higher efficiency of light delivery to the deep brain was achieved with ventricular instead of transcranial illumination. Our study demonstrates that it is possible to illuminate deep brain tissues transcranially, transsphenoidally and via different application routes. This opens therapeutic options for sufferers of PD or other cerebral diseases necessitating light therapy.

Original Source:

Quantitative analysis of transcranial and intraparenchymal light penetration in human cadaver brain tissue.

Tedford CE, DeLapp S, Jacques S, Anders J LumiThera, Inc., Poulsbo, Washington, 98370. - (Publication)
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 BACKGROUND AND OBJECTIVE: Photobiomodulation (PBM) also known as low-level light therapy has been used successfully for the treatment of injury and disease of the nervous system. The use of PBM to treat injury and diseases of the brain requires an in-depth understanding of light propagation through tissues including scalp, skull, meninges, and brain. This study investigated the light penetration gradients in the human cadaver brain using a Transcranial Laser System with a 30 mm diameter beam of 808 nm wavelength light. In addition, the wavelength-dependence of light scatter and absorbance in intraparenchymal brain tissue using 660, 808, and 940 nm wavelengths was investigated. in vivo. Lasers Surg. Med. 47:312-322, 2015. (c) 2015 Wiley Periodicals, Inc.

STUDY DESIGN/MATERIAL AND METHODS: Intact human cadaver heads (n = 8) were obtained for measurement of light propagation through the scalp/skull/meninges and into brain tissue. The cadaver heads were sectioned in either the transverse or mid-sagittal. The sectioned head was mounted into a cranial fixture with an 808 nm wavelength laser system illuminating the head from beneath with either pulsed-wave (PW) or continuous- wave (CW) laser light. A linear array of nine isotropic optical fibers on a 5 mm pitch was inserted into the brain tissue along the optical axis of the beam. Light collected from each fiber was delivered to a multichannel power meter. As the array was lowered into the tissue, the power from each probe was recorded at 5 mm increments until the inner aspect of the dura mater was reached. Intraparenchymal light penetration measurements were made by delivering a series of wavelengths (660, 808, and 940 nm) through a separate optical fiber within the array, which was offset from the array line by 5 mm. Local light penetration was determined and compared across the selected wavelengths.

RESULTS: Unfixed cadaver brains provide good anatomical localization and reliable measurements of light scatter and penetration in the CNS tissues. Transcranial application of 808 nm wavelength light penetrated the scalp, skull, meninges, and brain to a depth of approximately 40 mm with an effective attenuation coefficient for the system of 2.22 cm(-1) . No differences were observed in the results between the PW and CW laser light. The intraparenchymal studies demonstrated less absorption and scattering for the 808 nm wavelength light compared to the 660 or 940 nm wavelengths.

CONCLUSIONS: Transcranial light measurements of unfixed human cadaver brains allowed for determinations of light penetration variables. While unfixed human cadaver studies do not reflect all the conditions seen in the living condition, comparisons of light scatter and penetration and estimates of fluence levels can be used to establish further clinical dosing. The 808 nm wavelength light demonstrated superior CNS tissue penetration.

Original Source:

Did human hairlessness allow natural photobiomodulation 2 million years ago and enable photobiomodulation therapy today? This can explain the rapid expansion of our genus's brain.

Mathewson I - (Publication)
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 Retired Medical Practitioner, 42 Bundaleer Rd, Brookfield, Brisbane Q4069, Australia. Electronic address:

Present hypotheses to explain human hairlessness appear to be inadequate because hairlessness is not accompanied by any immediate benefit. A new, testable, hypothesis is advanced to explain our hairlessness based on photobiomodulation research, also known as low-level light therapy. This shows that red and near infrared radiation has a very beneficial effect on superficial tissues, including the brain. Random mutation/s resulting in complete hairlessness allowed early humans to receive daily doses of red and near infrared radiation at sunset. Photobiomodulation research shows this has a twofold effect: it results in increased mitochondrial respiratory chain activity with consequent ATP 'extrasynthesis' in all superficial tissues, including the brain. It also advantageously affects the expression of over 100 genes through the activation of transcription factor NFkB which results in cerebral metabolic and haemodynamic enhancement. It is also possible that melanin can supply electrons to the respiratory chain resulting in ATP extrasynthesis. These effects would start automatically as soon as hairlessness occurred resulting in a selective sweep of the mutation/s involved. This was followed by the very rapid brain evolution of the last 2my which, it is suggested, was due to intelligence-led evolution based initially on the increased energy and adeptness of the newly hairless individuals.

Original Source:

Transcranial laser therapy in acute stroke treatment: results of neurothera effectiveness and safety trial 3, a phase III clinical end point device trial.

Hacke W, Schellinger PD, Albers GW, Bornstein NM, Dahlof BL, Fulton R, Kasner SE, Shuaib A, Richieri SP, Dilly SG, Zivin J, Lees KR - (Publication)
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 From the Department of Neurology, Heidelberg University, Heidelberg, Germany (W.H.); Department of Neurology, Johannes Wesling Klinikum Minden, Minden, Germany (P.D.S.); Department of Neurology, Stanford Stroke Center, Palo Alto, CA (G.W.A.); Department of Neurology, Sackler Faculty of Medicine, Tel-Aviv University, Tel-Aviv, Israel (N.M.B.); Department of Internal Medicine, Sahlgrenski University Hospital Ostra, Goteborg University, Goteborg, Sweden (B.L.D.); Institute of Cardiovascular and Medical Sciences, Gardiner Institute, Western Infirmary and Faculty of Medicine, University of Glasgow, Glasgow, United Kingdom (R.F., K.R.L.); Department of Neurology, Hospital of the University of Pennsylvania, Philadelphia (S.E.K.); Division of Neurology, University of Alberta, Edmonton, Alberta, Canada (A.S.); Banyan Biomarkers, San Diego, CA (S.P.R.); Allergen Research Cooperation, San Mateo, CA (S.G.D.); and Department of Neurology, School of Medicine, University of California, San Diego (J. Z.).

Transcranial low-level laser therapy enhances learning, memory, and neuroprogenitor cells after traumatic brain injury in mice.

Xuan W, Vatansever F, Huang L, Hamblin MR - (Publication)
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 Ruikang Hospital Affiliated to Guangxi University of Chinese Medicine, Department of Otolaryngology, Nanning 530021, ChinabWellman Center for Photomedicine, Massachusetts General Hospital, Boston, Massachusetts 02114, United StatescHarvard Medical School. Wellman Center for Photomedicine, Massachusetts General Hospital, Boston, Massachusetts 02114, United StatescHarvard Medical School, Department of Dermatology, Boston, Massachusetts 02115, United States. Wellman Center for Photomedicine, Massachusetts General Hospital, Boston, Massachusetts 02114, United StatescHarvard Medical School, Department of Dermatology, Boston, Massachusetts 02115, United StatesdGuangxi Medical University, First Affiliated College. Wellman Center for Photomedicine, Massachusetts General Hospital, Boston, Massachusetts 02114, United StatescHarvard Medical School, Department of Dermatology, Boston, Massachusetts 02115, United StateseHarvard-MIT Division of Health Sciences and Technolo.

The use of transcranial low-level laser (light) therapy (tLLLT) to treat stroke and traumatic brain injury (TBI) is attracting increasing attention. We previously showed that LLLT using an 810-nm laser 4 h after controlled cortical impact (CCI)-TBI in mice could significantly improve the neurological severity score, decrease lesion volume, and reduce Fluoro-Jade staining for degenerating neurons. We obtained some evidence for neurogenesis in the region of the lesion. We now tested the hypothesis that tLLLT can improve performance on the Morris water maze (MWM, learning, and memory) and increase neurogenesis in the hippocampus and subventricular zone (SVZ) after CCI-TBI in mice. One and (to a greater extent) three daily laser treatments commencing 4-h post-TBI improved neurological performance as measured by wire grip and motion test especially at 3 and 4 weeks post-TBI. Improvements in visible and hidden platform latency and probe tests in MWM were seen at 4 weeks. Caspase-3 expression was lower in the lesion region at 4 days post-TBI. Double-stained BrdU-NeuN (neuroprogenitor cells) was increased in the dentate gyrus and SVZ. Increases in double-cortin (DCX) and TUJ-1 were also seen. Our study results suggest that tLLLT may improve TBI both by reducing cell death in the lesion and by stimulating neurogenesis.

Original Source:

660 nm red light-enhanced bone marrow mesenchymal stem cell transplantation for hypoxic-ischemic brain damage treatment.

Li X, Hou W, Wu X, Jiang W, Chen H, Xiao N, Zhou P - (Publication)
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 Key Laboratory of Biorheological Science and Technology, Ministry of Education, College of Bioengineering, Chongqing University, Chongqing, China. Chongqing Engineering Research Center for Medical Electronics Technology, Chongqing, China. Rehabilitation Center, Children's Hospital of Chongqing Medical University, Chongqing, China.

Bone marrow mesenchymal stem cell transplantation is an effective treatment for neonatal hypoxic- ischemic brain damage. However, the in vivo transplantation effects are poor and their survival, colonization and differentiation efficiencies are relatively low. Red or near-infrared light from 600-1,000 nm promotes cellular migration and prevents apoptosis. Thus, we hypothesized that the combination of red light with bone marrow mesenchymal stem cell transplantation would be effective for the treatment of hypoxic-ischemic brain damage. In this study, the migration and colonization of cultured bone marrow mesenchymal stem cells on primary neurons after oxygen-glucose deprivation were detected using Transwell assay. The results showed that, after a 40-hour irradiation under red light-emitting diodes at 660 nm and 60 mW/cm(2), an increasing number of green fluorescence-labeled bone marrow mesenchymal stem cells migrated towards hypoxic-ischemic damaged primary neurons. Meanwhile, neonatal rats with hypoxic-ischemic brain damage were given an intraperitoneal injection of 1 x 10(6) bone marrow mesenchymal stem cells, followed by irradiation under red light-emitting diodes at 660 nm and 60 mW/cm(2) for 7 successive days. Shuttle box test results showed that, after phototherapy and bone marrow mesenchymal stem cell transplantation, the active avoidance response rate of hypoxic- ischemic brain damage rats was significantly increased, which was higher than that after bone marrow mesenchymal stem cell transplantation alone. Experimental findings indicate that 660 nm red light emitting diode irradiation promotes the migration of bone marrow mesenchymal stem cells, thereby enhancing the contribution of cell transplantation in the treatment of hypoxic-ischemic brain damage.

Original Source:

Low-level laser therapy for traumatic brain injury in mice increases brain derived neurotrophic factor (BDNF) and synaptogenesis.

Xuan W, Agrawal T, Huang L, Gupta GK, Hamblin MR - (Publication)
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 Wellman Center for Photomedicine, Massachusetts General Hospital, 40 Blossom Street, Boston, MA 02114, USA; Department of Dermatology, Harvard Medical School, Boston, MA 02115, USA; Department of Otolaryngology, Traditional Chinese Medical University of Guangxi, Nanning, China.

Transcranial low-level laser (light) therapy (LLLT) is a new non-invasive approach to treating a range of brain disorders including traumatic brain injury (TBI). We (and others) have shown that applying near- infrared light to the head of animals that have suffered TBI produces improvement in neurological functioning, lessens the size of the brain lesion, reduces neuroinflammation, and stimulates the formation of new neurons. In the present study we used a controlled cortical impact TBI in mice and treated the mice either once (4 h post-TBI, 1-laser), or three daily applications (3-laser) with 810 nm CW laser 36 J/cm2 at 50 mW/cm2 . Similar to previous studies, the neurological severity score improved in laser- treated mice compared to untreated TBI mice at day 14 and continued to further improve at days 21 and 28 with 3-laser being better than 1-laser. Mice were sacrificed at days 7 and 28 and brains removed for immunofluorescence analysis. Brain-derived neurotrophic factor (BDNF) was significantly upregulated by laser treatment in the dentate gyrus of the hippocampus (DG) and the subventricular zone (SVZ) but not in the perilesional cortex (lesion) at day 7 but not at day 28. Synapsin-1 (a marker for synaptogenesis, the formation of new connections between existing neurons) was significantly upregulated in lesion and SVZ but not DG, at 28 days but not 7 days. The data suggest that the benefit of LLLT to the brain is partly mediated by stimulation of BDNF production, which may in turn encourage synaptogenesis. Moreover the pleiotropic benefits of BDNF in the brain suggest LLLT may have wider applications to neurodegenerative and psychiatric disorders. Neurological Severity Score (NSS) for TBI mice.

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Laser Acupuncture at HT7 Acupoint Improves Cognitive Deficit, Neuronal Loss, Oxidative Stress, and Functions of Cholinergic and Dopaminergic Systems in Animal Model of Parkinson's Disease.

Wattanathorn J, Sutalangka C - (Publication)
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 Department of Physiology, Faculty of Medicine, Khon Kaen University, Khon Kaen 40002, Thailand ; Integrative Complementary Alternative Medicine Research and Development Center, Khon Kaen University, Khon Kaen 40002, Thailand. Integrative Complementary Alternative Medicine Research and Development Center, Khon Kaen University, Khon Kaen 40002, Thailand ; Department of Physiology, Neuroscience Program, Faculty of Medicine, Khon Kaen University, Khon Kaen 40002, Thailand.

To date, the therapeutic strategy against cognitive impairment in Parkinson's disease (PD) is still not in satisfaction level and requires novel effective intervention. Based the oxidative stress reduction and cognitive enhancement induced by laser acupuncture at HT7, the beneficial effect of laser acupuncture at HT7 against cognitive impairment in PD has been focused. In this study, we aimed to determine the effect of laser acupuncture at HT7 on memory impairment, oxidative stress status, and the functions of both cholinergic and dopaminergic systems in hippocampus of animal model of PD. Male Wistar rats, weighing 180-220 g, were induced unilateral lesion at right substantianigra by 6-OHDA and were treated with laser acupuncture continuously at a period of 14 days. The results showed that laser acupuncture at HT7 enhanced memory and neuron density in CA3 and dentate gyrus. The decreased AChE, MAO-B, and MDA together with increased GSH-Px in hippocampus of a 6-OHDA lesion rats were also observed. In conclusion, laser acupuncture at HT7 can improve neuron degeneration and memory impairment in animal model of PD partly via the decreased oxidative stress and the improved cholinergic and dopaminergic functions. More researches concerning effect of treatment duration are still required.

Original Source:

Traumatic Brain Injury: A Major Medical Problem That Could Be Treated Using Transcranial, Red/Near-Infrared LED Photobiomodulation.

Naeser MA, Hamblin MR - (Publication)
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 1 VA Boston Healthcare System , Boston, Massachusetts. 2 Department of Neurology, Boston University School of Medicine , Boston, Massachusetts. 3 Wellman Center for Photomedicine, Massachusetts General Hospital , Boston, Massachusetts. 4 Department of Dermatology, Harvard Medical School , Boston, Massachusetts. 5 Harvard-MIT Division of Health Sciences and Technology , Cambridge, Massachusetts.

Original Source:

Low-level light in combination with metabolic modulators for effective therapy of injured brain.

Dong T, Zhang Q, Hamblin MR, Wu MX - (Publication)
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 Department of Dermatology, Harvard Medical School, Wellman Center for Photomedicine, Massachusetts General Hospital, Boston, Massachusetts, USA.

Vascular damage occurs frequently at the injured brain causing hypoxia and is associated with poor outcomes in the clinics. We found high levels of glycolysis, reduced adenosine triphosphate generation, and increased formation of reactive oxygen species and apoptosis in neurons under hypoxia. Strikingly, these adverse events were reversed significantly by noninvasive exposure of injured brain to low-level light (LLL). Low-level light illumination sustained the mitochondrial membrane potential, constrained cytochrome c leakage in hypoxic cells, and protected them from apoptosis, underscoring a unique property of LLL. The effect of LLL was further bolstered by combination with metabolic substrates such as pyruvate or lactate both in vivo and in vitro. The combinational treatment retained memory and learning activities of injured mice to a normal level, whereas other treatment displayed partial or severe deficiency in these cognitive functions. In accordance with well-protected learning and memory function, the hippocampal region primarily responsible for learning and memory was completely protected by combination treatment, in marked contrast to the severe loss of hippocampal tissue because of secondary damage in control mice. These data clearly suggest that energy metabolic modulators can additively or synergistically enhance the therapeutic effect of LLL in energy-producing insufficient tissue-like injured brain.Journal of Cerebral Blood Flow & Metabolism advance online publication, 13 May 2015; doi:10.1038/jcbfm.2015.87.

Preliminary results of highly localized plantar irradiation with low incident levels of mid-infrared energy which contributes to the prevention of dementia associated with underlying diabetes mellitus.

Ryotokuji K, Ishimaru K, Kihara K, Nakajima T, Otani S, Namiki Y - (Publication)
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 Stress-free Therapy Research Center, Ryotokuji University.

BACKGROUND AND AIMS: The incidence of vascular dementia (VD) and Alzheimer's disease (AD) has recently increased and the prevention of progression of these diseases is very difficult.

RESULTS: The application of pinpoint plantar long-wavelength infrared light irradiation (PP-LILI) to a patient's sole, at the point where the line drawn between the first and second metatarsal heads intersects with the vertical line from the medial malleolus, was effective in increasing blood flow to the facial artery, elevating high- density lipoprotein cholesterol (HDL-C) levels, and reducing insulin resistance.

CONCLUSIONS: We found that these effects of PP-LILI might be helpful for preventing VD and AD, conditions that are becoming a social problem in an aging Japanese society.

Original Source:

Differential Effects of 670 and 830 nm Red near Infrared Irradiation Therapy: A Comparative Study of Optic Nerve Injury, Retinal Degeneration, Traumatic Brain and Spinal Cord Injury.

Giacci MK, Wheeler L, Lovett S, Dishington E, Majda B, Bartlett CA, Thornton E, Harford-Wright E, Leonard A, Vink R, Harvey AR, Provis J, Dunlop SA, Hart NS, Hodgetts S, Natoli R, Van Den Heuvel C, Fitzgerald M - (Publication)
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 Experimental and Regenerative Neurosciences, The University of Western Australia, Crawley, Australia

Red/near-infrared irradiation therapy (R/NIR-IT) delivered by laser or light-emitting diode (LED) has improved functional outcomes in a range of CNS injuries. However, translation of R/NIR-IT to the clinic for treatment of neurotrauma has been hampered by lack of comparative information regarding the degree of penetration of the delivered irradiation to the injury site and the optimal treatment parameters for different CNS injuries. We compared the treatment efficacy of R/NIR-IT at 670 nm and 830 nm, provided by narrow-band LED arrays adjusted to produce equal irradiance, in four in vivo rat models of CNS injury: partial optic nerve transection, light-induced retinal degeneration, traumatic brain injury (TBI) and spinal cord injury (SCI). The number of photons of 670 nm or 830 nm light reaching the SCI injury site was 6.6% and 11.3% of emitted light respectively. Treatment of rats with 670 nm R/NIR-IT following partial optic nerve transection significantly increased the number of visual responses at 7 days after injury (P</=0.05); 830 nm R/NIR-IT was partially effective. 670 nm R/NIR-IT also significantly reduced reactive species and both 670 nm and 830 nm R/NIR-IT reduced hydroxynonenal immunoreactivity (P</=0.05) in this model. Pre-treatment of light-induced retinal degeneration with 670 nm R/NIR-IT significantly reduced the number of Tunel+ cells and 8-hydroxyguanosine immunoreactivity (P</=0.05); outcomes in 830 nm R/NIR-IT treated animals were not significantly different to controls.

Treatment of fluid-percussion TBI with 670 nm or 830 nm R/NIR-IT did not result in improvements in motor or sensory function or lesion size at 7 days (P>0.05). Similarly, treatment of contusive SCI with 670 nm or 830 nm R/NIR-IT did not result in significant improvements in functional recovery or reduced cyst size at 28 days (P>0.05). Outcomes from this comparative study indicate that it will be necessary to optimise delivery devices, wavelength, intensity and duration of R/NIR-IT individually for different CNS injury types.

PLoS One 2014 9(8) e104565

Original Source:

Low-Level Laser Therapy Ameliorates Disease Progression in a Mouse Model of Alzheimer's Disease.

Farfara D, Tuby H, Trudler D, Doron-Mandel E, Maltz L, Vassar RJ, Frenkel D, Oron U - (Publication)
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 Department of Neurobiology, George S. Wise Faculty of Life Sciences, Tel Aviv University, Tel Aviv, Israel.

Low-level laser therapy (LLLT) has been used to treat inflammation, tissue healing, and repair processes. We recently reported that LLLT to the bone marrow (BM) led to proliferation of mesenchymal stem cells (MSCs) and their homing in the ischemic heart suggesting its role in regenerative medicine. The aim of the present study was to investigate the ability of LLLT to stimulate MSCs of autologous BM in order to affect neurological behavior and beta-amyloid burden in progressive stages of Alzheimer's disease (AD) mouse model. MSCs from wild-type mice stimulated with LLLT showed to increase their ability to maturate towards a monocyte lineage and to increase phagocytosis activity towards soluble amyloid beta (Abeta). Furthermore, weekly LLLT to BM of AD mice for 2 months, starting at 4 months of age (progressive stage of AD), improved cognitive capacity and spatial learning, as compared to sham-treated AD mice. Histology revealed a significant reduction in Abeta brain burden. Our results suggest the use of LLLT as a therapeutic application in progressive stages of AD and imply its role in mediating MSC therapy in brain amyloidogenic diseases.

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Expression of mPGES-1 and IP mRNA is reduced by LLLT in both subplantar and brain tissues in the model of peripheral inflammation induced by carrageenan.

hagas LR, Silva JA Jr, de Almeida Pires J, Costa MS - (Publication)
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 Instituto de Pesquisa e Desenvolvimento - IP&D, Universidade do Vale do Paraiba - UNIVAP, Av. Shishima Hifumi, 2911. Urbanova, CEP 12244-000, Sao Jose dos Campos, SP, Brazil.

The increase in PGE2 production by microsomal PGE synthase-1 (mPGES-1) in CNS contributes to the severity of the inflammatory and pain responses in the model of edema formation and hyperalgesia induced by carrageenan. PGI2, alike to PGE2, plays an important role in the inflammation. Low-level laser therapy (LLLT) has been used in the treatment of inflammatory pathologies, reducing both pain and the acute inflammatory process. In this work, we studied the effect of LLLT on the expression of both mPGES-1 and IP messenger RNA (mRNA), in either subplantar or total brain tissues obtained from rats submitted to model of edema formation and hyperalgesia induced by carrageenan administration. The test sample consisted of 30 rats divided into five groups: A1 (control-saline), A2 (carrageenan-0.5 mg/paw), A3 (carrageenan-0.5 mg/paw + LLLT), A4 (carrageenan-1.0 mg/paw), and A5 (carrageenan-1.0 mg/paw + LLLT). The animals from groups A3 and A5 were irradiated 1 h after induction of inflammation by carrageenan injection. Continuous-wave red laser with wavelengths of 660 nm and dose of 7.5 J/cm2 was used. Six hours after carrageenan-induced inflammation, mPGES-1 and prostacyclin receptor (IP) mRNA expression were significantly increased both in subplantar and brain tissues. LLLT was able to reduce both mPGES-1 and IP mRNA expression in subplantar and brain tissues. We suggest that LLLT is able to reduce both inflammation and hyperalgesia observed in the model of edema formation and hyperalgesia induced by carrageenan, by a mechanism involving the decrease in the expression of both mPGES-1 and IP.

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The role of magnetolaserotherapy in the correction of the adaptive potential of the brain in the children suffering absence seizures.

- (Publication)
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 We have conducted a course of magnetic laser therapy targeted on the vegetative structures at the neck of the children suffering absence seizures in an attempt to optimize the functioning of the non-specific brain structures. The study has demonstrated that such treatment promotes normalization of the components of the orientation response to sound almost to the level observed in the healthy children. The alpha-index returned to the normal value as well.

Original Source:

Low-level laser therapy effectively prevents secondary brain injury induced by immediate early responsive gene X-1 deficiency.

Zhang Q, Zhou C, Hamblin MR, Wu MX - (Publication)
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 1] Wellman Center for Photomedicine, Massachusetts General Hospital, Boston, Massachusetts, USA [2] Department of Dermatology, Harvard Medical School, Boston, Massachusetts, USA. [3] Affiliated faculty member of the Harvard-MIT Division of Health Sciences and Technology, Cambridge, Massachusetts, USA.

A mild insult to the brain can sometimes trigger secondary brain injury, causing severe postconcussion syndrome, but the underlying mechanism is ill understood. We show here that secondary brain injury occurs consistently in mice lacking immediate early responsive gene X-1 (IEX-1), after a gentle impact to the head, which closely simulates mild traumatic brain injury in humans. The pathologic lesion was characterized by extensive cell death, widespread leukocyte infiltrates, and severe tissue loss. On the contrary, a similar insult did not induce any secondary injury in wild-type mice. Strikingly, noninvasive exposure of the injured head to a low-level laser at 4 hours after injury almost completely prevented the secondary brain injury in IEX-1 knockout mice. The low-level laser therapy (LLLT) suppressed proinflammatory cytokine expression like interleukin (IL)-1beta and IL-6 but upregulated TNF-alpha.

Moreover, although lack of IEX-1 compromised ATP synthesis, LLLT elevated its production in injured brain. The protective effect of LLLT may be ascribed to enhanced ATP production and selective modulation of proinflammatory mediators. This new closed head injury model provides an excellent tool to investigate the pathogenesis of secondary brain injury as well as the mechanism underlying the beneficial effect of LLLT.

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The Antidepressant Effect of Laser Acupuncture: A Comparison of the Resting Brain's Default Mode Network in Healthy and Depressed Subjects During Functional Magnetic Resonance Imaging.

Quah-Smith I, Suo C, Williams MA, Sachdev PS - (Publication)
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 School of Psychiatry, Faculty of Medicine, University of New South Wales (UNSW) , Australia. ; Neuropsychiatric Institute (NPI) , Prince of Wales Hospital, Randwick, Australia. Brain and Ageing Research Program, Centre for Healthy Brain Ageing, School of Psychiatry, UNSW Medicine, University of New South Wales , New South Wales, Australia. Macquarie Centre for Cognitive Sciences, Macquarie University , Sydney, Australia.

BACKGROUND: It has been suggested that the antidepressant effect of laser acupuncture involves modulation of the default mode network (DMN) or resting state network (RSN). In this study, the authors investigated changes in the DMN during laser acupuncture in depressed and nondepressed participants.

OBJECTIVE: To aim of this study was to determine if the modulation of the DMN effects by laser acupuncture in depressed participants are different from those of nondepressed participants. DESIGN: Randomized stimulation was performed with laser acupuncture on four putative antidepressant acupoints (LR 14, LR 8, CV 14, and HT 7) in a block on-off design, while the blood oxygenation level-dependent (BOLD) fMRI response was recorded from each subject's whole brain on a 3T scanner. DMN patterns of the participants were identified, using an independent component analysis. The identified DMN components from both the nondepressed group and the depressed group were then analytically compared using SPM5.

SETTING: This study took place at a research institute. SUBJECTS: Ten nondepressed participants and 10 depressed participants (DS) as confirmed by the Hamilton Depression Rating Scale (HAM-D) participated in this study.

INTERVENTION: Low Intensity Laser Acupuncture.

MAIN OUTCOME MEASURES: Significant DMN patterns in one group were greater than those in the other group.

RESULTS: The nondepressed participants had significant modulation of DMN in the frontal region at the medial frontal gyrus (verum laser>rest, p<0.001) for three acupoints (LR 14, LR 8, and CV 14). For the depressive participants, the DMN modulation occurred at the inferior parietal cortex and the cerebellum (verum laser>rest, p<0.001).

CONCLUSIONS: Laser acupuncture on LR 8, LR 14, and CV 14 stimulated both the anterior and posterior DMN in both the nondepressed and depressed participants.

However, in the nondepressed participants, there was consistently outstanding modulation of the anterior DMN at the medial frontal gyrus across all three acupoints. In the depressed participants, there was wider posterior DMN modulation at the parieto-temporal-limbic cortices. This is part of the antidepressant effect of laser acupuncture.

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Significant improvements on cognitive performance post- transcranial, red/near-infrared LED treatments in chronic, mild TBI: Open-protocol study.

Naeser MA, Zafonte R, Krengel MH, Martin PI, Frazier J, Hamblin M, Knight JA, Meehan W, Baker EH - (Publication)
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 VA Boston Healthcare System, 150 So. Huntington Ave., 12-A, Boston, Massachusetts, United States, 02130, 857-364-4030, 617-739-8926, Boston University School of Medicine, Neurology, 85 E. Concord St, Boston, Massachusetts, United States, 02118, 857-364-4030, 617-739-8926 ;

This pilot, open-protocol study examined whether scalp application of red and near-infrared (NIR) light- emitting diodes (LED) could improve cognition in patients with chronic, mild traumatic brain injury (mTBI). Application of red/NIR light improves mitochondrial function (especially in hypoxic/compromised cells) promoting increased ATP important for cellular metabolism. Nitric oxide is released locally, increasing regional cerebral blood flow. LED therapy is non-invasive, painless, and non- thermal (FDA-cleared, non-significant risk device). Eleven chronic, mTBI participants (26-62 Yr, 6M) with non-penetrating head injury and persistent cognitive dysfunction were treated for 18 outpatient sessions (MWF, 6 Wks), starting at 10 Mo to 8 Yr post- mTBI (MVA or sports-related; and one participant, IED blast injury). Four had a history of multiple concussions. Each LED cluster head (2.1" diameter, 500mW, 22.2mW/cm2) was applied for 10 min to each of 11 scalp placements (13 J/cm2). LEDs were placed on the midline from front-to-back hairline; and bilaterally on frontal, parietal, and temporal areas.

Neuropsychological testing was performed pre- LED, and at 1 Wk, 1 and 2 Mo post- the 18th treatment. A significant linear trend was observed for the effect of LED treatment over time for Stroop test for Executive Function, Trial 3 inhibition (p=.004); Stroop, Trial 4 inhibition switching (p=.003); California Verbal Learning Test (CVLT)-II, Total Trials 1-5 (p=.003); and CVLT-II, Long Delay Free Recall (p=.006). Participants reported improved sleep, and fewer PTSD symptoms, if present. Participants and family reported better ability to perform social, interpersonal and occupational functions. These open-protocol data suggest placebo controlled studies are warranted.

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Low-level laser therapy (LLLT) reduces the COX-2 mRNA expression in both subplantar and total brain tissues in the model of peripheral inflammation induced by administration of carrageenan.

Prianti AC Jr, Silva JA Jr, Dos Santos RF, Rosseti IB, Costa MS - (Publication)
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 Instituto de Pesquisa e Desenvolvimento-IP&D, Universidade do Vale do Paraiba-UNIVAP, Av. Shishima Hifumi 2911, Sao Jose dos Campos, Urbanova, CEP: 12244-000, SP, Brazil.

In the classical model of edema formation and hyperalgesia induced by carrageenan administration in rat paw, the increase in prostaglandin E2 (PGE2) production in the central nervous system (CNS) contributes to the severity of the inflammatory and pain responses. Prostaglandins are generated by the cyclooxygenase (COX). There are two distinct COX isoforms, COX-1 and COX-2. In inflammatory tissues, COX-2 is greatly expressed producing proinflammatory prostaglandins (PGs). Low-level laser therapy (LLLT) has been used in the treatment of inflammatory pathologies, reducing both pain and acute inflammatory process. Herein we studied the effect of LLLT on both COX-2 and COX-1 messenger RNA (mRNA) expression in either subplantar or brain tissues taken from rats treated with carrageenan. The experiment was designed as follows: A1 (saline), A2 (carrageenan-0.5 mg/paw), A3 (carrageenan-0.5 mg/paw + LLLT), A4 (carrageenan-1.0 mg/paw), and A5 (carrageenan-1.0 mg/paw + LLLT). Animals from the A3 and A5 groups were irradiated at 1 h after carrageenan administration, using a diode laser with an output power of 30 mW and a wavelength of 660 nm. The laser beam covered an area of 0.785 cm2, resulting in an energy dosage of 7.5 J/cm2. Both COX-2 and COX-1 mRNAs were measured by RT-PCR. Six hours after carrageenan administration, COX-2 mRNA expression was significantly increased both in the subplantar (2.2-4.1-fold) and total brain (8.65-13.79-fold) tissues. COX-1 mRNA expression was not changed. LLLT (7.5 J/cm2) reduced significantly the COX-2 mRNA expression both in the subplantar (~2.5-fold) and brain (4.84-9.67-fold) tissues. The results show that LLLT is able to reduce COX-2 mRNA expression. It is possible that the mechanism of LLLT decreasing hyperalgesia is also related to its effect in reducing the COX-2 expression in the CNS.

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Non-pharmaceutical therapies for stroke: mechanisms and clinical implications.

Chen F, Qi Z, Luo Y, Hinchliffe T, Ding G, Xia Y, Ji X - (Publication)
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 Cerebrovascular Diseases Research Institute, Xuanwu Hospital of Capital Medical University, Beijing, Beijing 100053, China. The Vivian L. Smith Department of Neurosurgery, The University of Texas Medical School at Houston, Houston, TX 77030, USA. Shanghai Research Center for Acupuncture and Meridian, Shanghai 201203, China. The Vivian L. Smith Department of Neurosurgery, The University of Texas Medical School at Houston, Houston, TX 77030, USA. Electronic address: Cerebrovascular Diseases Research Institute, Xuanwu Hospital of Capital Medical University, Beijing, Beijing 100053, China. Electronic address: jixm@ccmu.

Stroke is deemed a worldwide leading cause of neurological disability and death, however, there is currently no promising pharmacotherapy for acute ischemic stroke aside from intravenous or intra-arterial thrombolysis. Yet because of the narrow therapeutic time window involved, thrombolytic application is very restricted in clinical settings. Accumulating data suggest that non-pharmaceutical therapies for stroke might provide new opportunities for stroke treatment. Here we review recent research progress in the mechanisms and clinical implications of non-pharmaceutical therapies, mainly including neuroprotective approaches such as hypothermia, ischemic/hypoxic conditioning, acupuncture, medical gases and transcranial laser therapy. In addition, we briefly summarize mechanical endovascular recanalization devices and recovery devices for the treatment of the chronic phase of stroke and discuss the relative merits of these devices.

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Photobiomodulation with near infrared light mitigates Alzheimer's disease- related pathology in cerebral cortex - evidence from two transgenic mouse models.

Purushothuman S, Johnstone DM, Nandasena C, Mitrofanis J, Stone J - (Publication)
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 Bosch Institute, University of Sydney NSW 2006, Australia.

INTRODUCTION: Previous work has demonstrated the efficacy of irradiating tissue with red to infrared light in mitigating cerebral pathology and degeneration in animal models of stroke, traumatic brain injury, parkinsonism and Alzheimer's disease (AD). Using mouse models, we explored the neuroprotective effect of near infrared light (NIr) treatment, delivered at an age when substantial pathology is already present in the cerebral cortex.

METHODS: We studied two mouse models with AD- related pathologies: the K369I tau transgenic model (K3), engineered to develop neurofibrillary tangles, and the APPswe/PSEN1dE9 transgenic model (APP/PS1), engineered to develop amyloid plaques. Mice were treated with NIr 20 times over a four-week period and histochemistry was used to quantify AD- related pathological hallmarks and other markers of cell damage in the neocortex and hippocampus.

RESULTS: In the K3 mice, NIr treatment was associated with a reduction in hyperphosphorylated tau, neurofibrillary tangles and oxidative stress markers (4-hydroxynonenal and 8-hydroxy-2'- deoxyguanosine) to near wildtype levels in the neocortex and hippocampus, and with a restoration of expression of the mitochondrial marker cytochrome c oxidase in surviving neurons. In the APP/PS1 mice, NIr treatment was associated with a reduction in the size and number of amyloid-beta plaques in the neocortex and hippocampus.

CONCLUSIONS: Our results, in two transgenic mouse models, suggest that NIr may have potential as an effective, minimally-invasive intervention for mitigating, and even reversing, progressive cerebral degenerations.

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Photobiomodulation inside the brain: a novel method of applying near- infrared light intracranially and its impact on dopaminergic cell survival in MPTP-treated mice.

Moro C, Massri NE, Torres N, Ratel D, De Jaeger X, Chabrol C, Perraut F, Bourgerette A, Berger M, Purushothuman S, Johnstone D, Stone J, Mitrofanis J, Benabid AL CEA-Leti, Grenoble, France; - (Publication)
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 Object Previous experimental studies have documented the neuroprotection of damaged or diseased cells after applying, from outside the brain, near-infrared light (NIr) to the brain by using external light- emitting diodes (LEDs) or laser devices. In the present study, the authors describe an effective and reliable surgical method of applying to the brain, from inside the brain, NIr to the brain. They developed a novel internal surgical device that delivers the NIr to brain regions very close to target damaged or diseased cells. They suggest that this device will be useful in applying NIr within the large human brain, particularly if the target cells have a very deep location. Methods An optical fiber linked to an LED or laser device was surgically implanted into the lateral ventricle of BALB/c mice or Sprague-Dawley rats.

The authors explored the feasibility of the internal device, measured the NIr signal through living tissue, looked for evidence of toxicity at doses higher than those required for neuroprotection, and confirmed the neuroprotective effect of NIr on dopaminergic cells in the substantia nigra pars compacta (SNc) in an acute 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) model of Parkinson disease in mice. Results The device was stable in freely moving animals, and the NIr filled the cranial cavity. Measurements showed that the NIr intensity declined as distance from the source increased across the brain (65% per mm) but was detectable up to 10 mm away. At neuroprotective (0.16 mW) and much higher (67 mW) intensities, the NIr caused no observable behavioral deficits, nor was there evidence of tissue necrosis at the fiber tip, where radiation was most intense. Finally, the intracranially delivered NIr protected SNc cells against MPTP insult; there were consistently more dopaminergic cells in MPTP-treated mice irradiated with NIr than in those that were not irradiated. Conclusions In summary, the authors showed that NIr can be applied intracranially, does not have toxic side effects, and is neuroprotective.

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Laser acupuncture improves memory impairment in an animal model of Alzheimer's disease.

Sutalangka C, Wattanathorn J, Muchimapura S, Thukham-Mee W, Wannanon P, Tong-Un T - (Publication)
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 Department of Physiology (Neuroscience Program), Faculty of Medicine, Khon Kaen University, Khon Kaen, Thailand; Integrative Complementary Alternative Medicine Research and Development Group, Khon Kaen University, Khon Kaen, Thailand.

The burden of Alzheimer's disease is continually rising globally, especially in the Asia-Pacific region. Unfortunately, the efficacy of the therapeutic strategy is still very limited. Because the effect of acupuncture at HT7 can improve learning and memory, the beneficial effect of laser acupuncture, a noninvasive form of acupuncture, at HT7 on memory improvement in patients with Alzheimer's disease has been a focus of research. To elucidate this issue, we used AF64A, a cholinotoxin, to induce memory impairment in male Wistar rats, which weighed 180-220 g. Then, the animals were treated with laser acupuncture either at HT7 or at a sham acupoint once daily for 10 minutes for a period of 14 days.

Spatial memory assessments were performed at 1, 7, and 14 days after AF64A administration and at the end of the experiment, and the changes in the malondialdehyde (MDA) level and in the superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GSH-Px), and acetylcholinesterase (AChE) activities in the hippocampus were recorded. The results showed that laser acupuncture significantly suppressed AChE activity in the hippocampus. Although laser acupuncture enhanced SOD and CAT activities, no reduction in MDA level in this area was observed. Therefore, laser acupuncture at HT7 is a potential strategy to attenuate memory impairment in patients with Alzheimer's disease. However, further research, especially on the toxicity of laser acupuncture following repetitive exposure, is essential.

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Low-Level Laser Therapy Rescues Dendrite Atrophy via Upregulating BDNF Expression: Implications for Alzheimer's Disease.

Meng C, He Z, Xing D - (Publication)
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 MOE Key Laboratory of Laser Life Science and Institute of Laser Life Science, College of Biophotonics, South China Normal University, Guangzhou 510631, China.

Downregulation of brain-derived neurotrophic factor (BDNF) in the hippocampus occurs early in the progression of Alzheimer's disease (AD). Since BDNF plays a critical role in neuronal survival and dendrite growth, BDNF upregulation may contribute to rescue dendrite atrophy and cell loss in AD. Low- level laser therapy (LLLT) has been demonstrated to regulate neuronal function both in vitro and in vivo. In the present study, we found that LLLT rescued neurons loss and dendritic atrophy via upregulation of BDNF in both Abeta-treated hippocampal neurons and cultured APP/PS1 mouse hippocampal neurons. Photoactivation of transcription factor CRE-binding protein (CREB) increased both BDNF mRNA and protein expression, since knockdown CREB blocked the effects of LLLT. Furthermore, CREB-regulated transcription was in an ERK-dependent manner. Inhibition of ERK attenuated the DNA-binding efficiency of CREB to BDNF promoter. In addition, dendrite growth was improved after LLLT, characterized by upregulation of Rac1 activity and PSD-95 expression, and the increase in length, branching, and spine density of dendrites in hippocampal neurons. Together, these studies suggest that upregulation of BDNF with LLLT by activation of ERK/CREB pathway can ameliorate Abeta-induced neurons loss and dendritic atrophy, thus identifying a novel pathway by which LLLT protects against Abeta-induced neurotoxicity.

Our research may provide a feasible therapeutic approach to control the progression of AD. J Neurosci 2013 Aug 14 33(33) 13505-17

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Differential brain effects of laser and needle acupuncture at LR8 using functional MRI.

Quah-Smith I, Williams MA, Lundeberg T, Suo C, Sachdev P - (Publication)
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 School of Psychiatry, University of New South Wales and Neuropsychiatric Institute (NPI), Prince of Wales Hospital, , Sydney, New South Wales, Australia.

OBJECTIVE: While needle acupuncture is a well-accepted technique, laser acupuncture is being increasingly used in clinical practice. The differential effects of the two techniques are of interest. We examine this in relation to brain effects of activation of LR8, a putative acupuncture point for depression, using functional MRI (fMRI).

METHODS: Sixteen healthy participants were randomised to receive low intensity laser acupuncture to LR8 on one side and needle acupuncture to the contralateral LR8.

Stimulation was in an on-off block design and brain patterns were recorded under fMRI.

RESULTS: Significant activation occurred in the left precuneus during laser acupuncture compared with needle acupuncture and significant activation occurred in the left precentral gyrus during needle acupuncture compared with laser acupuncture.

CONCLUSIONS: Laser and needle acupuncture at LR8 in healthy participants produced different brain patterns. Laser acupuncture activated the precuneus relevant to mood in the posterior default mode network while needle acupuncture activated the parietal cortical region associated with the primary motor cortex. Further investigations are warranted to evaluate the clinical relevance of these effects.

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Possibilities of magnetic-laser therapy in comprehensive treatment of patients with brain concussion in acute period.

- (Publication)
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 The efficacy of magnetic-laser therapy used according to the method developed by us was studied in patients having the brain concussion (BC) in an acute period. The study was based on the dynamics of values of the evoked vestibular potentials and the disease clinical course. It was shown that following the magnetic-laser therapy in combination with traditional pharmacotherapy in BC acute period, the statistically significant positive changes were registered in the quantitative characteristics of the evoked vestibular brain potentials that correlated with the dynamics of the disease clinical course. The data obtained substantiate the possibility of using the magnetic-laser therapy in patients with a mild craniocereblal injury in an acute period.

Original Source:

Transcranial low-level laser therapy improves neurological performance in traumatic brain injury in mice: effect of treatment repetition regimen.

Xuan W, Vatansever F, Huang L, Wu Q, Xuan Y, Dai T, Ando T, Xu T, Huang YY, Hamblin MR - (Publication)
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 Wellman Center for Photomedicine, Massachusetts General Hospital, Boston, Massachusetts, United States of America ; Department of Dermatology, Harvard Medical School, Boston, Massachusetts, United States of America ; Department of Otolaryngology, Traditional Chinese Medical University of Guangxi, Nanning, China.

Low-level laser (light) therapy (LLLT) has been clinically applied around the world for a spectrum of disorders requiring healing, regeneration and prevention of tissue death. One area that is attracting growing interest in this scope is the use of transcranial LLLT to treat stroke and traumatic brain injury (TBI). We developed a mouse model of severe TBI induced by controlled cortical impact and explored the effect of different treatment schedules. Adult male BALB/c mice were divided into 3 broad groups (a) sham-TBI sham-treatment, (b) real-TBI sham-treatment, and (c) real-TBI active-treatment. Mice received active-treatment (transcranial LLLT by continuous wave 810 nm laser, 25 mW/cm(2), 18 J/cm(2), spot diameter 1 cm) while sham-treatment was immobilization only, delivered either as a single treatment at 4 hours post TBI, as 3 daily treatments commencing at 4 hours post TBI or as 14 daily treatments. Mice were sacrificed at 0, 4, 7, 14 and 28 days post-TBI for histology or histomorphometry, and injected with bromodeoxyuridine (BrdU) at days 21-27 to allow identification of proliferating cells. Mice with severe TBI treated with 1-laser Tx (and to a greater extent 3-laser Tx) had significant improvements in neurological severity score (NSS), and wire-grip and motion test (WGMT). However 14-laser Tx provided no benefit over TBI-sham control. Mice receiving 1- and 3-laser Tx had smaller lesion size at 28-days (although the size increased over 4 weeks in all TBI-groups) and less Fluoro-Jade staining for degenerating neurons (at 14 days) than in TBI control and 14-laser Tx groups. There were more BrdU- positive cells in the lesion in 1- and 3-laser groups suggesting LLLT may increase neurogenesis.

Transcranial NIR laser may provide benefit in cases of acute TBI provided the optimum treatment regimen is employed.

PLoS One 2013 8(1) e53454

Original Source:

The brain-derived neurotrophic factor, nerve growth factor, neurotrophin-3, and induced nitric oxide synthase expressions after low-level laser therapy in an axonotmesis experimental model.

Gomes LE, Dalmarco EM, Andre ES - (Publication)
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 1 Laboratorio de Fisioterapia Neurologica Experimental (LFNE), Departamento de Fisioterapia, Universidade Regional de Blumenau (FURB) , Blumenau, Brazil .

Abstract Background data: A robust body of evidence has shown that low-level laser therapy (LLLT) improves peripheral nerve regeneration. However, the biochemical background triggered in this process is not yet fully understood.

Objective: The purpose of this study was to evaluate the mRNA expression of neurotrophic factors (brain-derived neurotrophic factor [BDNF], nerve growth factor [NGF], and neurotrophin-3, [NT-3]) and also an inflammatory marker (induced nitric oxide synthase [iNOS]) in an axonotmesis experimental model after low-level laser therapy.

Methods: Thirty-six adult male Wistar rats (250-350 g) were subjected to right sciatic nerve crush injury, and 24 h later, the animals in the three different experimental groups (n=18) were irradiated on a daily basis with helium-neon laser (collimated HeNe laser, continuous emission, wavelength: 632.8 nm, power density: 0.5 mW/cm(2), irradiation time: 20 sec, energy density: 10 J/cm(2)) during 7, 14, and 21 consecutive days, respectively. The control group (n=18) underwent the same procedures, but with the equipment turned off. At the end of the experiments, animals were killed with an overdose of anesthesia to remove samples from the sciatic nerve lesion epicenter to determine the mRNA expression of BDNF, NGF, NT-3 and iNOS enzyme.

Results: Comparisons between groups showed that HeNe laser increased the mRNA expression of both BDNF and NGF factors after 14 days of LLLT, with peak expression at the 21st day. Increase in NT-3 mRNA expression was not observed. In addition, HeNe laser produced iNOS expression reduction, which played an important role in the inflammatory process.

Conclusions: The reported data could have a relevant practical value because LLLT is a noninvasive procedure, and have revealed significant increase in neurotrophic factor expressions and inflammatory process reduction, opening the possibility of using LLLT as an important aid to nerve regeneration process.

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A new treatment protocol using photobiomodulation and muscle/bone/joint recovery techniques having a dramatic effect on a stroke patient's recovery: a new weapon for clinicians.

Boonswang NA, Chicchi M, Lukachek A, Curtiss D - (Publication)
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 Cardiothoracic Surgery Department, Easton Hospital, Easton, Pennsylvania, USA.

The subject of this case study is a 29-year-old woman who suffered a brainstem stroke. She remained severely dizzy, had a non-functional left hand secondary to weakness, severe spasticity in the right hand, a right lateral sixth nerve palsy and was unable to ambulate on presentation. The stroke occurred 2 years before presentation. The subject had been treated for 21 months at two different stroke rehabilitation centres before presentation. Our stroke protocol includes photobiomodulation administered with the XR3T-1 device (manufactured by THOR) and 'muscle/bone/joint/soft tissue' recovery techniques. The patient was seen once a week for 8 weeks and treatment sessions lasted approximately 60 mins. The results were dramatic: after 8 weeks of implementation of our protocol, the patient demonstrated positive change in every area of her deficits as determined by improvements in physical examination findings.

The gains achieved at 8 weeks have been maintained to this day and she continues to be treated once every 4 weeks.

BMJ Case Rep 2012 2012

Original Source:

Transcranial low level laser (light) therapy for traumatic brain injury.

Huang YY, Gupta A, Vecchio D, Arce VJ, Huang SF, Xuan W, Hamblin MR - (Publication)
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 Wellman Center for Photomedicine, Massachusetts General Hospital, BAR414, 40 Blossom Street, Boston, MA 02114, USA; Department of Dermatology, Harvard Medical School, Boston, MA 02115, USA; Aesthetic and Plastic Center of Guangxi Medical University, Nanning, China.

We review the use of transcranial low-level laser (light) therapy (LLLT) as a possible treatment for traumatic-brain injury (TBI). The basic mechanisms of LLLT at the cellular and molecular level and its effects on the brain are outlined. Many interacting processes may contribute to the beneficial effects in TBI including neuroprotection, reduction of inflammation and stimulation of neurogenesis. Animal studies and clinical trials of transcranial-LLLT for ischemic stroke are summarized. Several laboratories have shown that LLLT is effective in increasing neurological performance and memory and learning in mouse models of TBI. There have been case report papers that show beneficial effects of transcranial- LLLT in a total of three patients with chronic TBI. Our laboratory has conducted three studies on LLLT and TBI in mice. One looked at pulsed-vs-continuous wave laser-irradiation and found 10 Hz to be superior. The second looked at four different laser-wavelengths (660, 730, 810, and 980 nm); only 660 and 810 nm were effective. The last looked at different treatment repetition regimens (1, 3 and 14-daily laser-treatments). ((c) 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim).

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Near-infrared laser treatment of acute stroke : From bench to bedside.

Schellinger PD, Kohrmann M - (Publication)
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 Neurologische Klinik und Neurogeriatrie, Johannes Wesling Klinikum, Hans-Nolte-Str. 1, 32429, Minden, Deutschland,

Near-infrared laser therapy (NIRLT) as a transcranial laser therapy (TLT) is currently being investigated as a neuroreparatory and neuroprotective treatment for acute ischemic stroke patients in a pivotal phase III trial (NEST-3). In this review we cover the theoretical background, experimental studies, translational research and the clinical trial program.

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Near-Infrared Photobiomodulation in an Animal Model of Traumatic Brain Injury: Improvements at the Behavioral and Biochemical Levels.

Quirk BJ, Torbey M, Buchmann E, Verma S, Whelan HT 1 Medical College of Wisconsin , Milwaukee, Wisconsin. - (Publication)
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 Abstract Objective: The purpose of this was to evaluate the neuroprotective effects of near-infrared (NIR) light using an in-vivo rodent model of traumatic brain injury (TBI), controlled cortical impact (CCI), and to characterize changes at the behavioral and biochemical levels.

Background data: NIR upregulates mitochondrial function, and decreases oxidative stress. Mitochondrial oxidative stress and apoptosis are important in TBI. NIR enhanced cell viability and mitochondrial function in previous in-vitro TBI models, supporting potential NIR in-vivo benefits.

Methods: Sprague-Dawley rats were divided into three groups: severe TBI, sham surgery, and anesthetization only (behavioral response only). Cohorts in each group were administered either no NIR or NIR. They received two 670 nm LED treatments (5 min, 50 mW/cm (2), 15 J/cm(2)) per day for 72 h (chemical analysis) or 10 days (behavioral). During the recovery period, animals were tested for locomotor and behavioral activities using a TruScan device. Frozen brain tissue was obtained at 72 h and evaluated for apoptotic markers and reduced glutathione (GSH) levels.

Results: Significant differences were seen in the TBI plus and minus NIR (TBI+/-) and sham plus and minus NIR (S+/-) comparisons for some of the TruScan nose poke parameters. A statistically significant decrease was found in the Bax pro-apoptotic marker attributable to NIR exposure, along with lesser increases in Bcl-2 anti-apoptotic marker and GSH levels.

Conclusions: These results show statistically significant, preclinical outcomes that support the use of NIR treatment after TBI in effecting changes at the behavioral, cellular, and chemical levels.

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Nitrergic response to Clostridium perfringens infection in the rat brain regions: effect of red light irradiation.

Movsesyan HA, Alchujyan NKh, Movsesyan NH, Guevorkian AG, Hairapetyan HL, Barsegyan KA, Kevorkian GA - (Publication)
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 H.Buniatian Institute of Biochemistry NAS RA, 5/1 P. Sevak St., 0014, Yerevan, Republic of Armenia.

A single intraperitoneal injection of a gram-positive pathogen Clostridium perfringens (Cp) causes a remarkable down-regulation the constitutive nitric oxide synthase (cNOS) with a simultaneous increase in the activity of inducible NOS (iNOS) and the level of reactive nitrogen species in the rat brain major regions (cortex, striatum, hippocampus and hypothalamus) at 48 h post-administration of Cp. Treatment by both a semiconductor laser (SCL) and/or a light-emitting diode (LED) with same wavelength, energy density and time exposure (continuous wave, lambda=654 nm, fluence=1.27 J/cm(2), time exposure=600s) could modulate brain nitrergic response following Cp-infection. Besides, unlike the LED, the SCL- irradiation prevents the cNOS inhibition in all the studied brain regions and might be useful in restoring its function in neurotransmission and cerebral blood flow, along with providing a protective effect against nitrosative stress-induced iNOS-mediated injury in the brain regions.

Original Source:

Effect of 710-nm Visible Light Irradiation on Neuroprotection and Immune Function after Stroke.

Choi DH, Lim JH, Lee KH, Kim MY, Kim HY, Shin CY, Han SH, Lee J - (Publication)
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 Center for Neuroscience Research, SMART Institute of Advanced Biomedical Science, Konkuk University School of Medicine, Seoul, Republic of Korea.

Objective: The phototherapeutic effects of low level infrared laser irradiation (808 nm) on brain neuronal cell protection after stroke have been presented recently. We previously reported that 710-nm wavelength visible light (VIS) increases total lymphocyte counts in vivo, especially CD4(+) T lymphocytes. In this study, we investigated the effects of 710-nm VIS irradiation on neuronal protection and recovery correlating with cellular immunity in stroke rats.

Methods: Rats were subjected to 90-min middle cerebral artery occlusion (MCAO) followed by reperfusion and were divided into two groups: irradiation and no irradiation. The irradiation group had been exposed to 710-nm VIS for 3 weeks after MCAO establishment or sham operation. The helper T cell (CD4(+)) count in the whole blood and infarct volume were measured. Messenger RNA expression levels of IL-4 and IL-10 in peripheral blood mononuclear cells were measured, a histologic study including microglia activation and regulatory T (Treg) cell markers, neurological severity scoring and a parallel bar walking test were all performed.

Results: CD4(+) cell count was reduced after MCAO but was significantly increased by 710-nm VIS irradiation. The infarct sizes were decreased in the MCAO + irradiation group compared with the MCAO control group. IL-10 mRNA expression and the immunoreactivity of Treg cells were increased in the MCAO + irradiation group compared with the MCAO control group. Increased microglia activation after MCAO was reduced by 710-nm VIS irradiation. The irradiation group also showed improved neurological severity score levels and step fault scores after MCAO.

Conclusions: Our data suggest that 710-nm VIS irradiation may activate cellular immunity, reduce brain infarction and ultimately induce functional recovery in a stroke animal model.

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Transcranial laser therapy for acute ischemic stroke: a pooled analysis of NEST-1 and NEST-2.

- (Publication)
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 Department of Neurology, University of New Mexico, Albuquerque, NM, USA.

BACKGROUND: NeuroThera Effectiveness and Safety Trials (NEST) 1 and 2 have demonstrated safety of transcranial laser therapy (TLT) for human treatment in acute ischemic stroke. NEST 1 study suggested efficacy of TLT but the following NEST 2, despite strong signals, missed reaching significance on its primary efficacy endpoint. In order to assess efficacy in a larger cohort, a pooled analysis was therefore performed.

METHODS: The two studies were first compared for heterogeneity, and then a pooled analysis was performed to assess overall safety and efficacy, and examined particular subgroups. The primary endpoint for the pooled analysis was dichotomized modified Rankin scale (mRS) 0-2 at 90 days.

RESULTS: Efficacy analysis for the intention-to-treat population was based on a total of 778 patients. Baseline characteristics and prognostic factors were balanced between the two groups. The TLT group (n= 410) success rate measured by the dichotomized 90-day mRS was significantly higher compared with the sham group (n = 368) (P = 0.003, OR: 1.67, 95% CI: 1.19-2.35). The distribution of scores on the 90- day mRS was significantly different in TLT compared with sham (P = 0.0005 Cochran-Mantel-Haenszel). Subgroup analysis identified moderate strokes as a predictor of better treatment response.

CONCLUSIONS: This pooled analysis support the likelihood that transcranial laser therapy is effective for the treatment of acute ischemic stroke when initiated within 24 h of stroke onset. If ultimately confirmed, transcranial laser therapy will change management and improve outcomes of far more patients with acute ischemic stroke.

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Photobiomodulation enhances nigral dopaminergic cell survival in a chronic MPTP mouse model of Parkinson's disease.

Peoples C, Spana S, Ashkan K, Benabid AL, Stone J, Baker GE, Mitrofanis J Discipline of Anatomy & Histology F13, University of Sydney, Australia. - (Publication)
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 We have shown previously that photobiomodulation or near-infrared light (NIr) treatment protects dopaminergic cells of the substantia nigra pars compacta (SNc) in an acute MPTP (1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine) model of Parkinson's disease (PD). In this study, we tested the protective and rescue action of NIr treatment in a chronic MPTP model, developed to resemble more closely the slow progressive degeneration in PD patients. We examined three regions of dopaminergic cells, the SNc, periaqueductal grey matter (PaG) and zona incerta-hypothalamus (ZI-Hyp). BALB/c mice had MPTP or saline injections over five weeks, followed by a three-week survival. NIr treatment was applied either at the same time as (simultaneous series) or after (post-treatment series) the MPTP insult. There were four groups within each series; Saline, Saline-NIr, MPTP and MPTP-NIr. Brains were processed for tyrosine hydroxylase (TH) immunochemistry and cell number was analysed using the optical fractionator method. In the SNc, there was a significant reduction ( approximately 45%) in TH(+) cell number in the MPTP groups compared to the saline controls of both series. In the MPTP-NIr groups of both series, TH(+) cell number was significantly higher ( approximately 25%) than in the MPTP groups, but lower than in the saline controls ( approximately 20%). By contrast in the PaG and ZI-Hyp, there were no significant differences in TH(+) cell number between the MPTP an MPTP-NIr groups of either series. In summary, exposure to NIr either at the same time or well after chronic MPTP insult saved many SNc dopaminergic cells from degeneration.

Original Source:

Low-level laser therapy for closed-head traumatic brain injury in mice: effect of different wavelengths.

Wu Q, Xuan W, Ando T, Xu T, Huang L, Huang YY, Dai T, Dhital S, Sharma SK, Whalen MJ, Hamblin MR - (Publication)
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 Wellman Center for Photomedicine, Massachusetts General Hospital, Boston, Massachusetts; Department of Dermatology, Harvard Medical School, Boston, Massachusetts; Department of Burns and Plastic Surgery, Jinan Central Hospital Affiliated to Shandong University, Jinan, China.

BACKGROUND AND OBJECTIVES: Traumatic brain injury (TBI) affects millions worldwide and is without effective treatment. One area that is attracting growing interest is the use of transcranial low-level laser therapy (LLLT) to treat TBI. The fact that near-infrared light can penetrate into the brain would allow non-invasive treatment to be carried out with a low likelihood of treatment-related adverse events. LLLT may treat TBI by increasing respiration in the mitochondria, causing activation of transcription factors, reducing inflammatory mediators and oxidative stress, and inhibiting apoptosis.

STUDY DESIGN/MATERIALS AND METHODS: We tested LLLT in a mouse model of closed-head TBI produced by a controlled weight drop onto the skull. Mice received a single treatment with continuous-wave 665, 730, 810, or 980 nm lasers (36 J/cm(2) delivered at 150 mW/cm(2) ) 4-hour post-TBI and were followed up by neurological performance testing for 4 weeks.

RESULTS: Mice with moderate-to-severe TBI treated with 665 and 810 nm laser (but not with 730 or 980 nm) had a significant improvement in Neurological Severity Score that increased over the course of the follow-up compared to sham-treated controls. Morphometry of brain sections showed a reduction in small deficits in 665 and 810 nm laser treated mouse brains at 28 days.

CONCLUSIONS: The effectiveness of 810 nm agrees with previous publications, and together with the effectiveness of 660 nm and non-effectiveness of 730 and 980 nm can be explained by the absorption spectrum of cytochrome oxidase, the candidate mitochondrial chromophore in transcranial LLLT. Lasers Surg. Med. (c) 2012 Wiley Periodicals, Inc.

Original Source:

Therapeutic effect of near infrared (NIR) light on Parkinson's disease models.

Quirk BJ, Desmet KD, Henry M, Buchmann E, Wong-Riley M, Eells JT, Whelan HT - (Publication)
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 Department of Neurology, Medical College of Wisconsin, 8701 W. Watertown Plank Rd, Milwaukee, WI, 53226, USA.

Parkinson's disease (PD) is a neurodegenerative disorder that affects large numbers of people, particularly those of a more advanced age. Mitochondrial dysfunction plays a central role in PD, especially in the electron transport chain. This mitochondrial role allows the use of inhibitors of complex I and IV in PD models, and enhancers of complex IV activity, such as NIR light, to be used as possible therapy. PD models fall into two main categories; cell cultures and animal models. In cell cultures, primary neurons, mutant neuroblastoma cells, and cell cybrids have been studied in conjunction with NIR light. Primary neurons show protection or recovery of function and morphology by NIR light after toxic insult.

Neuroblastoma cells, with a gene for mutant alpha-synuclein, show similar results. Cell cybrids, containing mtDNA from PD patients, show restoration of mitochondrial transport and complex I and IV assembly. Animal models include toxin-insulted mice, and alpha-synuclein transgenic mice. Functional recovery of the animals, chemical and histological evidence, and delayed disease progression show the potential of NIR light in treating Parkinson's disease.

Original Source:

Near infrared Transcranial Laser Therapy applied at Various Modes to Mice Following Traumatic Brain Injury Significantly Reduces Long-Term Neurological Deficits.

Oron U - (Publication)
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 Ramat Aviv, Tel-Aviv, Israel, 69978;

Near-infrared transcranial laser therapy (TLT) has been found to modulate various biological processes including traumatic brain injury (TBI). Following TBI in mice, in this study we assessed the possibility of various near-infrared TLT modes (pulsed vs. continuous) producing a beneficial effect on the long-term neurobehavioral outcome and brain lesions of these mice. TBI was induced by a weight-drop device, and neurobehavioral function was assessed from one hour and up to 56 days post-trauma using a neurological severity score (NSS). The extent of recovery is expressed as dNSS, the difference between the initial score, and that at any other, later, time point. An 808nm Ga-Al-As diode laser was employed transcranially 4, 6 or 8 hrs post-trauma to illuminate the entire cortex of the brain. Mice were divided into several groups of 6-8 mice: one control group that received a sham treatment and experimental groups that received either TLT continuous wave (CW) or pulsed wave (PW) mode transcranially. MRI was taken prior to sacrifice 56 days post-CHI. From 5 to 28 days post-TBI, the NSS of the laser-treated mice were significantly lower (p<0.05) than the non-laser-treated, control mice. The percentage of surviving mice that demonstrated full recovery 56 days post-CHI, namely NSS=0 (as in intact mice) was the highest (63%) in the group that had received TLT in the PW mode at 100 Hz. In addition, MRI analysis demonstrated significantly smaller infarct lesion volumes in laser treated mice as compared to control. Our data suggest that non-invasive TLT of mice post-TBI provides a significant long-term functional neurological benefit, and that the pulsed laser mode at 100 Hz is the preferred mode for such treatment. Key words: low-level laser therapy; mice; traumatic brain injury; pulsed laser; motor function, MRI.

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670 nm Laser Light and EGCG Complementarily Reduce Amyloid-beta Aggregates in Human Neuroblastoma Cells: Basis for Treatment of Alzheimer's Disease?

Sommer AP, Bieschke J, Friedrich RP, Zhu D, Wanker EE, Fecht HJ, Mereles D, Hunstein W - (Publication)
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 1 Institute of Micro and Nanomaterials, Nanobionic Laboratory, University of Ulm , Ulm, Germany .

Abstract Objective: The aim of the present study is to present the results of in vitro experiments with possible relevance in the treatment of Alzheimer's disease (AD).

Background Data: Despite intensive research efforts, there is no treatment for AD. One root cause of AD is the extra- and intracellular deposition of amyloid-beta (Abeta) fibrils in the brain. Recently, it was shown that extracellular Abeta can enter brain cells, resulting in neurotoxicity.

Methods: After internalization of Abeta(42) into human neuroblastoma (SH-EP) cells, they were irradiated with moderately intense 670-nm laser light (1000 Wm (-2)) and/or treated with epigallocatechin gallate (EGCG).

Results: In irradiated cells, Abeta(42) aggregate amounts were significantly lower than in nonirradiated cells. Likewise, in EGCG-treated cells, Abeta(42) aggregate amounts were significantly lower than in non-EGCG-treated cells. Except for the cells simultaneously laden with Abeta(42) and EGCG, there was a significant increase in cell numbers in response to laser irradiation. EGCG alone had no effect on cell proliferation. Laser irradiation significantly increased ATP levels in Abeta(42)-free cells, when compared to nonirradiated cells. Laser- induced clearance of Abeta(42) aggregates occurred at the expense of cellular ATP.

Conclusions: Irradiation with moderate levels of 670-nm light and EGCG supplementation complementarily reduces Abeta aggregates in SH-EP cells. Transcranial penetration of moderate levels of red to near-infrared (NIR) light has already been amply exploited in the treatment of patients with acute stroke; the blood-brain barrier (BBB) penetration of EGCG has been demonstrated in animals. We hope that our approach will inspire a practical therapy for AD.

Original Source:

Comparison of Therapeutic Effects between Pulsed and Continuous Wave 810-nm Wavelength Laser Irradiation for Traumatic Brain Injury in Mice.

Ando T, Xuan W, Xu T, Dai T, Sharma SK, Kharkwal GB, Huang YY, Wu Q, Whalen MJ, Sato S, Obara M, Hamblin MR - (Publication)
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 Wellman Center for Photomedicine, Massachusetts General Hospital, Boston, Massachusetts, United States of America.

BACKGROUND AND OBJECTIVE: Transcranial low-level laser therapy (LLLT) using near-infrared light can efficiently penetrate through the scalp and skull and could allow non-invasive treatment for traumatic brain injury (TBI). In the present study, we compared the therapeutic effect using 810-nm wavelength laser light in continuous and pulsed wave modes in a mouse model of TBI.

STUDY DESIGN/MATERIALS AND METHODS: TBI was induced by a controlled cortical-impact device and 4-hours post-TBI 1-group received a sham treatment and 3-groups received a single exposure to transcranial LLLT, either continuous wave or pulsed at 10-Hz or 100-Hz with a 50% duty cycle. An 810-nm Ga-Al-As diode laser delivered a spot with diameter of 1-cm onto the injured head with a power density of 50-mW/cm(2) for 12-minutes giving a fluence of 36-J/cm(2). Neurological severity score (NSS) and body weight were measured up to 4 weeks. Mice were sacrificed at 2, 15 and 28 days post-TBI and the lesion size was histologically analyzed. The quantity of ATP production in the brain tissue was determined immediately after laser irradiation. We examined the role of LLLT on the psychological state of the mice at 1 day and 4 weeks after TBI using tail suspension test and forced swim test.

RESULTS: The 810-nm laser pulsed at 10-Hz was the most effective judged by improvement in NSS and body weight although the other laser regimens were also effective. The brain lesion volume of mice treated with 10-Hz pulsed-laser irradiation was significantly lower than control group at 15-days and 4-weeks post-TBI. Moreover, we found an antidepressant effect of LLLT at 4-weeks as shown by forced swim and tail suspension tests.

CONCLUSION: The therapeutic effect of LLLT for TBI with an 810-nm laser was more effective at 10-Hz pulse frequency than at CW and 100-Hz. This finding may provide a new insight into biological mechanisms of LLLT.

PLoS One 2011 6(10) e26212

Original Source:

Noninvasive brain stimulation in traumatic brain injury.

Demirtas-Tatlidede A, Vahabzadeh-Hagh AM, Bernabeu M, Tormos JM, Pascual-Leone A - (Publication)
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 Berenson-Allen Center for Noninvasive Brain Stimulation, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, Massachusetts, USA.

OBJECTIVE: To review novel techniques of noninvasive brain stimulation (NBS), which may have value in assessment and treatment of traumatic brain injury (TBI).

METHODS: Review of the following techniques: transcranial magnetic stimulation, transcranial direct current stimulation, low-level laser therapy, and transcranial Doppler sonography. Furthermore, we provide a brief overview of TMS studies to date.

MAIN FINDINGS: We describe the rationale for the use of these techniques in TBI, discuss their possible mechanisms of action, and raise a number of considerations relevant to translation of these methods to clinical use. Depending on the stimulation parameters, NBS may enable suppression of the acute glutamatergic hyperexcitability following TBI and/or counter the excessive GABAergic effects in the subacute stage. In the chronic stage, brain stimulation coupled to rehabilitation may enhance behavioral recovery, learning of new skills, and cortical plasticity. Correlative animal models and comprehensive safety trials seem critical to establish the use of these modalities in TBI.

CONCLUSIONS: Different forms of NBS techniques harbor the promise of diagnostic and therapeutic utility, particularly to guide processes of cortical reorganization and enable functional restoration in TBI. Future lines of safety research and well-designed clinical trials in TBI are warranted to determine the capability of NBS to promote recovery and minimize disability.

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Violet laser acupuncture-part 1: effects on brain circulation.

Litscher G, Huang T, Wang L, Zhang W - (Publication)
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 Research Unit of Biomedical Engineering in Anesthesia and Intensive Care Medicine and TCM Research Center Graz, Medical University of Graz, Graz, Austria.

Violet laser acupuncture using a wavelength of 405 nm has been investigated in only a few scientific studies. The aim of this study was to provide selective evidence of a specific effect of violet laser acupuncture on mean cerebral blood flow velocity using a Doppler ultrasound technique. A transcranial Doppler sonography construction was developed especially for this study to monitor blood flow profiles in the basilar and middle cerebral arteries simultaneously and continuously. The acupuncture point Dazhui on the upper back was tested in a controlled study with 10 healthy volunteers (24.9 +/- 3.3 years, mean age +/- SD; 5 females, 5 males). In addition to an on/off-effect, violet laser stimulation increased the blood flow velocity in the basilar artery significantly (p < 0.001) compared with the reference interval before laser acupuncture. In the middle cerebral artery, only minimal, nonsignificant changes in blood flow velocity were seen. Metal needle acupuncture at the same point intensified the effects; however, blood flow profiles did not change significantly during and after stimulation with a deactivated violet laser.

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Improved Cognitive Function After Transcranial, Light-Emitting Diode Treatments in Chronic, Traumatic Brain Injury: Two Case Reports.

Naeser MA, Saltmarche A, Krengel MH, Hamblin MR, Knight JA 1 VA Boston Healthcare System , Boston, Massachusetts. - (Publication)
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 Abstract Objective: Two chronic, traumatic brain injury (TBI) cases, where cognition improved following treatment with red and near-infrared light-emitting diodes (LEDs), applied transcranially to forehead and scalp areas, are presented.

Background: Significant benefits have been reported following application of transcranial, low-level laser therapy (LLLT) to humans with acute stroke and mice with acute TBI. These are the first case reports documenting improved cognitive function in chronic, TBI patients treated with transcranial LED.

Methods: Treatments were applied bilaterally and to midline sagittal areas using LED cluster heads [2.1' diameter, 61 diodes (9 x 633 nm, 52 x 870 nm); 12-15 mW per diode; total power: 500 mW; 22.2 mW/cm(2); 13.3 J/cm(2) at scalp (estimated 0.4 J/cm(2) to cortex)].

Results: Seven years after closed-head TBI from a motor vehicle accident, Patient 1 began transcranial LED treatments. Pre- LED, her ability for sustained attention (computer work) lasted 20 min. After eight weekly LED treatments, her sustained attention time increased to 3 h. The patient performs nightly home treatments (5 years); if she stops treating for more than 2 weeks, she regresses. Patient 2 had a history of closed-head trauma (sports/military, and recent fall), and magnetic resonance imaging showed frontoparietal atrophy. Pre- LED, she was on medical disability for 5 months. After 4 months of nightly LED treatments at home, medical disability discontinued; she returned to working full-time as an executive consultant with an international technology consulting firm. Neuropsychological testing after 9 months of transcranial LED indicated significant improvement (+1, +2SD) in executive function (inhibition, inhibition accuracy) and memory, as well as reduction in post-traumatic stress disorder. If she stops treating for more than 1 week, she regresses. At the time of this report, both patients are continuing treatment.

Conclusions: Transcranial LED may improve cognition, reduce costs in TBI treatment, and be applied at home. Controlled studies are warranted.

Original Source:

Taking a light approach to treating acute ischemic stroke patients: Transcranial near-infrared laser therapy translational science.

Lapchak PA - (Publication)
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 Cedars-Sinai Medical Center, Department of Neurology, Los Angeles, California, USA.

Abstract Transcranial near-infrared laser therapy (NILT) has been investigated as a novel neuroprotective treatment for acute ischemic stroke (AIS), for approximately 10 years. Two clinical trials, NeuroThera Effectiveness and Safety Trial (NEST)-1 and NEST-2, have evaluated the use of NILT to promote clinical recovery in patients with AIS. This review covers preclinical, translational, and clinical studies documented during the period 1997-2010. The primary aim of this article is to detail the development profile of NILT to treat AIS. Secondly, insight into possible mechanisms involved in light therapy will be presented. Lastly, possible new directions that should be considered to improve the efficacy profile of NILT in AIS patients will be discussed. The use of NILT was advanced to clinical trials based upon extensive translational research using multiple species. NILT, which may promote functional and behavioral recovery via a mitochondrial mechanism and by enhancing cerebral blood flow, may eventually be established as an Food and Drug Administration (FDA)-approved treatment for stroke. The NEST-3 trial, which is the pivotal trial for FDA approval, should incorporate hypotheses derived from translational studies to ensure efficacy in patients. Future NILT studies should consider administration of a thrombolytic to enhance cerebral reperfusion alongside NILT neuroprotection.

Ann Med 2010 Dec 42(8) 576-86

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Different brain network activations induced by modulation and nonmodulation laser acupuncture.

Hsieh CW, Wu JH, Hsieh CH, Wang QF, Chen JH - (Publication)
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 Department of Photonic and Communication Engineering, Asia University, Taichung 41354, Taiwan.

The aim of this study is to compare the distinct cerebral activation with continued wave (CW) and 10 Hz- modulated wave (MW) stimulation during low-level laser acupuncture. Functional magnetic resonance imaging (fMRI) studies were performed to investigate the possible mechanism during laser acupuncture stimulation at the left foot's yongquan (K1) acupoint. There are 12 healthy right-handed volunteers for each type of laser stimulation (10-Hz-Modulated wave: 8 males and 4 females; continued wave: 9 males and 3 females). The analysis of multisubjects in this experiment was applied by random-effect (RFX) analysis. In CW groups, significant activations were found within the inferior parietal lobule, the primary somatosensory cortex, and the precuneus of left parietal lobe. Medial and superior frontal gyrus of left frontal lobe were also aroused. In MW groups, significant activations were found within the primary motor cortex and middle temporal gyrus of left hemisphere and bilateral cuneus. Placebo stimulation did not show any activation. Most activation areas were involved in the functions of memory, attention, and self-consciousness. The results showed the cerebral hemodynamic responses of two laser acupuncture stimulation modes and implied that its mechanism was not only based upon afferent sensory information processing, but that it also had the hemodynamic property altered during external stimulation.

Original Source:

The brain effects of laser acupuncture in healthy individuals: an FMRI investigation.

Quah-Smith I, Sachdev PS, Wen W, Chen X, Williams MA - (Publication)
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 School of Psychiatry, Faculty of Medicine, University of New South Wales, Randwick, New South Wales, Australia.

BACKGROUND: As laser acupuncture is being increasingly used to treat mental disorders, we sought to determine whether it has a biologically plausible effect by using functional magnetic resonance imaging (fMRI) to investigate the cerebral activation patterns from laser stimulation of relevant acupoints.

METHODOLOGY/PRINCIPAL FINDINGS: Ten healthy subjects were randomly stimulated with a fibreoptic infrared laser on 4 acupoints (LR14, CV14, LR8 and HT7) used for depression following the principles of Traditional Chinese Medicine (TCM), and 1 control non-acupoint (sham point) in a blocked design (alternating verum laser and placebo laser/rest blocks), while the blood oxygenation level- dependent (BOLD) fMRI response was recorded from the whole brain on a 3T scanner. Many of the acupoint laser stimulation conditions resulted in different patterns of neural activity. Regions with significantly increased activation included the limbic cortex (cingulate) and the frontal lobe (middle and superior frontal gyrus). Laser acupuncture tended to be associated with ipsilateral brain activation and contralateral deactivation that therefore cannot be simply attributed to somatosensory stimulation.

CONCLUSIONS/SIGNIFICANCE: We found that laser stimulation of acupoints lead to activation of frontal-limbic-striatal brain regions, with the pattern of neural activity somewhat different for each acupuncture point. This is the first study to investigate laser acupuncture on a group of acupoints useful in the management of depression. Differing activity patterns depending on the acupoint site were demonstrated, suggesting that neurological effects vary with the site of stimulation. The mechanisms of activation and deactivation and their effects on depression warrant further investigation.

PLoS One 2010 5(9)

Original Source:

The evolution of transcranial laser therapy for acute ischemic stroke, including a pooled analysis of NEST-1 and NEST-2.

Stemer AB, Huisa BN, Zivin JA - (Publication)
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 University of California, San Diego Medical Center, Medical Office North, 3rd floor, Suite 3, 200 West Arbor Drive #8466, San Diego, CA 92103-8466, USA.

Intravenous tissue plasminogen activator is the only proven therapy for acute ischemic stroke. Not enough patients are eligible for treatment and additional new therapies are needed. Recently, laser technology has been applied to acute ischemic stroke. This noninvasive technique uses near-infrared wavelengths applied to the scalp within 24 h of symptom onset. The mechanism is incompletely understood but may involve increased mitochondrial adenosine triphosphate production. Animal models demonstrated safety and efficacy warranting randomized controlled trials in humans. NEST-1 (phase 2) and NEST-2 (phase 3) confirmed the safety of transcranial laser therapy, although efficacy was not found in NEST-2. Pooled analysis of NEST-1 and NEST-2 revealed a significantly improved success rate in patients treated with laser therapy. Further phase 3 testing is planned and may create a new paradigm for the treatment of acute ischemic stroke.

Original Source:

Transcranial near infrared laser treatment (NILT) increases cortical adenosine-5'-triphosphate (ATP) content following embolic strokes in rabbits.

Lapchak PA, De Taboada L - (Publication)
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 University of California San Diego, Department of Neuroscience, 9500 Gilman Drive MTF316, La Jolla, CA 92093-0624, USA.

Transcranial near infrared laser therapy (NILT) improves behavioral outcome following embolic strokes in embolized rabbits and clinical rating scores in acute ischemic stroke (AIS) patients; however, the cellular mechanism(s) involved in NILT neuroprotection have not been elucidated. It has been proposed that mitochondrial energy production may underlie a response to NILT, but this has not been demonstrated using an in vivo embolic stroke model. Thus, we evaluated the effect of NILT on cortical ATP content using the rabbit small clot embolic stroke model (RSCEM), the model originally used to demonstrate NILT efficacy and initiate the NEST-1 clinical trial. Five minutes following embolization, rabbits were exposed to 2 min of NILT using an 808 nm laser source, which was driven to output either continuous wave (CW), or pulsed wave modes (PW). Three hours after embolization, the cerebral cortex was excised and processed for the measurement of ATP content using a standard luciferin-luciferase assay. NILT-treated rabbits were directly compared to sham-treated embolized rabbits and naive control rabbits.

Embolization decreased cortical ATP content in ischemic cortex by 45% compared to naive rabbits, a decrease that was attenuated by CW NILT which resulted in a 41% increase in cortical ATP content compared to the sham embolized group (p>0.05). The absolute increase in ATP content was 22.5% compared to naive rabbits. Following PW NILT, which delivered 5 (PW1) and 35 (PW2) times more energy than CW, we measured a 157% (PW1 p=0.0032) and 221% (PW2 p=0.0001) increase in cortical ATP content, respectively, compared to the sham embolized group. That represented a 41% and 77% increase in ATP content compared to naive control rabbits. This is the first demonstration that embolization can decrease ATP content in rabbit cortex and that NILT significantly increases cortical ATP content in embolized rabbits, an effect that is correlated with cortical fluence and the mode of NILT delivery. The data provide new insight into the molecular mechanisms associated with clinical improvement following NILT.

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Reduced axonal transport in Parkinson's disease cybrid neurites is restored by light therapy.

Trimmer PA, Schwartz KM, Borland MK, De Taboada L, Streeter J, Oron U - (Publication)
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 University of Virginia, Morris K Udall Parkinson's Research Center of Excellence and Department of Neurology, Charlottesville, Virginia, USA.

ABSTRACT: BACKGROUND: It has been hypothesized that reduced axonal transport contributes to the degeneration of neuronal processes in Parkinson's disease (PD). Mitochondria supply the adenosine triphosphate (ATP) needed to support axonal transport and contribute to many other cellular functions essential for the survival of neuronal cells. Furthermore, mitochondria in PD tissues are metabolically and functionally compromised. To address this hypothesis, we measured the velocity of mitochondrial movement in human transmitochondrial cybrid "cytoplasmic hybrid" neuronal cells bearing mitochondrial DNA from patients with sporadic PD and disease-free age-matched volunteer controls (CNT). The absorption of low level, near-infrared laser light by components of the mitochondrial electron transport chain (mtETC) enhances mitochondrial metabolism, stimulates oxidative phosphorylation and improves redox capacity. PD and CNT cybrid neuronal cells were exposed to near-infrared laser light to determine if the velocity of mitochondrial movement can be restored by low level light therapy (LLLT).

Axonal transport of labeled mitochondria was documented by time lapse microscopy in dopaminergic PD and CNT cybrid neuronal cells before and after illumination with an 810 nm diode laser (50 mW/cm2) for 40 seconds. Oxygen utilization and assembly of mtETC complexes were also determined.

RESULTS: The velocity of mitochondrial movement in PD cybrid neuronal cells (0.175 +/- 0.005 SEM) was significantly reduced (p < 0.02) compared to mitochondrial movement in disease free CNT cybrid neuronal cells (0.232 +/- 0.017 SEM). For two hours after LLLT, the average velocity of mitochondrial movement in PD cybrid neurites was significantly (p < 0.003) increased (to 0.224 +/- 0.02 SEM) and restored to levels comparable to CNT. Mitochondrial movement in CNT cybrid neurites was unaltered by LLLT (0.232 +/- 0.017 SEM). Assembly of complexes in the mtETC was reduced and oxygen utilization was altered in PD cybrid neuronal cells. PD cybrid neuronal cell lines with the most dysfunctional mtETC assembly and oxygen utilization profiles were least responsive to LLLT.

CONCLUSION: The results from this study support our proposal that axonal transport is reduced in sporadic PD and that a single, brief treatment with near-infrared light can restore axonal transport to control levels. These results are the first demonstration that LLLT can increase axonal transport in model human dopaminergic neuronal cells and they suggest that LLLT could be developed as a novel treatment to improve neuronal function in patients with PD.

Original Source:

The cybrid model of sporadic Parkinson's disease.

Trimmer PA, Bennett JP Jr - (Publication)
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 Morris K. Udall Parkinson's Disease Research Center of Excellence, Department of Neurology, University of Virginia, Charlottesville, VA 22908, USA.

Parkinson's disease (PD) is the eponym attached to the most prevalent neurodegenerative movement disorder of adults, derived from observations of an early nineteenth century physician and paleontologist, James Parkinson, and is now recognized to encompass much more than a movement disorder clinically or dopamine neuron death pathologically. Most PD ( approximately 90%) is sporadic (sPD), is associated with mitochondrial deficiencies and has been studied in cell and animal models arising from the use of mitochondrial toxins that unfortunately have not predicted clinical efficacy to slow disease progression in humans. We have extensively studied the cytoplasmic hybrid ("cybrid") model of sPD in which donor mtDNAs are introduced into and expressed in neural tumor cells with identical nuclear genetic and environmental backgrounds. sPD cybrids demonstrate many abnormalities in which increased oxidative stress drives downstream antioxidant response and cell death activating signaling pathways. sPD cybrids regulate mitochondrial ETC genes and gene ontology families like sPD brain. sPD cybrids spontaneously form Lewy bodies and Lewy neurites, linking mtDNA expression to neuropathology, and demonstrate impaired organelle transport in processes and reduced mitochondrial respiration. Our recent studies show that near-infrared laser light therapy normalizes mitochondrial movement and can stimulate respiration in sPD cybrid neurons, and mitochondrial gene therapy can restore respiration and stimulate mitochondrial ETC gene and protein expression. sPD cybrids have provided multiple lines of circumstantial evidence linking mtDNA to sPD pathogenesis and can serve as platforms for therapy development. sPD cybrid models can be improved by the use of non-tumor human stem cell-derived neural precursor cells and by an introduction of postmortem brain mtDNA to test its causality directly.

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Laser therapy of painful shoulder and shoulder-hand syndrome in treatment of patients after the stroke.

Karabegovic A, Kapidzic-Durakovic S, Ljuca F - (Publication)
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 Clinic for Physical Medicine and Rehabilitation, University Clinical Centre, Faculty of Medicine, University of Tuzla, Trnovac b.b., 75 000 Tuzla, Bosnia and Herzegovina.

The common complication after stroke is pain and dysfunction of shoulder of paralyzed arm, as well as the swelling of the hand. The aim of this study was to determine the effects of LASER therapy and to correlate with electrotherapy (TENS, stabile galvanization) in subjects after stroke. We analyzed 70 subjects after stroke with pain in shoulder and oedema of paralyzed hand. The examinees were divided in two groups of 35, and they were treated in the Clinic for Physical Medicine and Rehabilitation in Tuzla during 2006 and 2007. Experimental group (EG) had a treatment with LASER, while the control group (CG) was treated with electrotherapy. Both groups had kinesis therapy and ice massage. All patients were examined on the admission and discharge by using the VAS, DASH, Barthel index and FIM. The pain intensity in shoulder was significantly reduced in EG (p<0,0001), swelling is lowered in EG (p=0,01).

Barthel index in both groups was significant higher (p<0,01). DASH was significantly improved after LASER therapy in EG (p<0,01). EG had higher level of independency (p<0,01). LASER therapy used on EG shows significantly better results in reducing pain, swelling, disability and improvement of independency.

Effectiveness and Safety of Transcranial Laser Therapy for Acute Ischemic Stroke.

Zivin JA, Albers GW, Bornstein N, Chippendale T, Dahlof B, Devlin T, Fisher M, Hacke W, Holt W, Ilic S, Kasner S, Lew R, Nash M, Perez J, Rymer M, Schellinger P, Schneider D, Schwab S, Veltkamp R, Walker M, Streeter J - (Publication)
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From the Department of Neurosciences, University of California San Diego, La Jolla, Calif; Stanford Stroke Center, Stanford University Medical Center, Palo Alto, Calif; Tel Aviv Medical Center, Tel Aviv, Israel; Scripps Hospital, Encinitas, Calif; Sahlgrenska University Hospital, Gothenburg, Sweden; Erlanger Health System, Chattanooga, Tenn; University of Massachusetts Medical School, Worcester, Mass; Department of Neurology, Universitat Heidelberg, Heidelberg, Germany; Fawcett Memorial Hospital, Port Charlotte, Fla; Triage Wireless, Inc, San Diego, Calif; the Department of Neurology, University of Pennsylvania School of Medicine, Philadelphia, Pa; Boston University, Boston, Mass; DeKalb Neurology Associates, Decatur, Ga; Hospital Nacional Dos de Mayo, Lima, Peru; St. Luke's Health System, Kansas City, Mo; Universitatsklinikum Erlangen, Erlangen, Germany; the Department of Neurology, Universitat Leipzig, Leipzig, Germany; Universitatsklinikum Erlangen, Erlangen, Germany; Department of Neurology, Universitat Heidelberg, Heidelberg, Germany; Stanford Center for Biomedical Informatics Research, Stanford School of Medicine, Palo Alto, Calif; and PhotoThera, Inc, Carlsbad, Calif.

BACKGROUND AND PURPOSE: We hypothesized that transcranial laser therapy (TLT) can use near- infrared laser technology to treat acute ischemic stroke. The NeuroThera Effectiveness and Safety Trial-2 (NEST-2) tested the safety and efficacy of TLT in acute ischemic stroke.

METHODS: This double-blind, randomized study compared TLT treatment to sham control. Patients receiving tissue plasminogen activator and patients with evidence of hemorrhagic infarct were excluded. The primary efficacy end point was a favorable 90-day score of 0 to 2 assessed by the modified Rankin Scale. Other 90-day end points included the overall shift in modified Rankin Scale and assessments of change in the National Institutes of Health Stroke Scale score.

RESULTS: We randomized 660 patients: 331 received TLT and 327 received sham; 120 (36.3%) in the TLT group achieved favorable outcome versus 101 (30.9%), in the sham group (P=0.094), odds ratio 1.38 (95% CI, 0.95 to 2.00). Comparable results were seen for the other outcome measures. Although no prespecified test achieved significance, a post hoc analysis of patients with a baseline National Institutes of Health Stroke Scale score of <16 showed a favorable outcome at 90 days on the primary end point (P<0.044). Mortality rates and serious adverse events did not differ between groups with 17.5% and 17.4% mortality, 37.8% and 41.8% serious adverse events for TLT and sham, respectively.

CONCLUSIONS: TLT within 24 hours from stroke onset demonstrated safety but did not meet formal statistical significance for efficacy. However, all predefined analyses showed a favorable trend, consistent with the previous clinical trial (NEST-1). Both studies indicate that mortality and adverse event rates were not adversely affected by TLT. A definitive trial with refined baseline National Institutes of Health Stroke Scale exclusion criteria is planned.

Original Source:

Effect of three different intensities of infrared laser energy on the levels of amino acid neurotransmitters in the cortex and hippocampus of rat brain.

Ahmed NA, Radwan NM, Ibrahim KM, Khedr ME, El Aziz MA, Khadrawy YA Zoology Department, Faculty of Science, Cairo University, Cairo, Egypt. - (Publication)
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 OBJECTIVE: The aim of this study is to investigate the effects of three different intensities of infrared diode laser radiation on amino acid neurotransmitters in the cortex and hippocampus of rat brain.

BACKGROUND DATA: Lasers are known to induce different neurological effects such as pain relief, anesthesia, and neurosuppressive effects; however, the precise mechanisms of these effects are not clearly elucidated. Amino acid neurotransmitters (glutamate, aspartate, glutamine, gamma-aminobutyric acid [GABA], glycine, and taurine) play vital roles in the central nervous system (CNS).

MATERIALS AND METHODS: The shaved scalp of each rat was exposed to different intensities of infrared laser energy (500, 190, and 90 mW) and then the rats were sacrificed after 1 h, 7 d, and 14 d of daily laser irradiation. The control groups were exposed to the same conditions but without exposure to laser. The concentrations of amino acid neurotransmitters were measured by high-performance liquid chromatography (HPLC).

RESULTS: The rats subjected to 500 mW of laser irradiation had a significant decrease in glutamate, aspartate, and taurine in the cortex, and a significant decrease in hippocampal GABA. In the cortices of rats exposed to 190 mW of laser irradiation, an increase in aspartate accompanied by a decrease in glutamine were observed. In the hippocampus, other changes were seen. The rats irradiated with 90 mW showed a decrease in cortical glutamate, aspartate, and glutamine, and an increase in glycine, while in the hippocampus an increase in glutamate, aspartate, and GABA were recorded.

CONCLUSION: We conclude that daily laser irradiation at 90 mW produced the most pronounced inhibitory effect in the cortex after 7 d. This finding may explain the reported neurosuppressive effect of infrared laser energy on axonal conduction of hippocampal and cortical tissues of rat brain.

Original Source:

Laser therapy in acute stroke treatment.

Yip S, Zivin J - (Publication)
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 Department of Neuroscience, University of California, San Diego, 9500 Gilman Drive, La Jolla, CA 92093-0624, USA.

Recent development of near infrared light therapy (NILT) as an acute stroke treatment is promising. In various preclinical animal stroke models, NILT has been shown to be effective in improving long-term stroke outcome. More importantly, NILT has a long postischemic therapeutic window that has not been previously observed in other treatment modalities. The preliminary efficacy and safety of NILT in acute stroke patients were demonstrated in the recently published phase II NeuroThera Effectiveness and Safety Trial (NEST-1). If confirmed by the NEST-II trial, NILT will revolutionize acute stroke management as ut has a long time window (possible 24 hr) for therapy. Moreover, understanding the mechanisms of action of NILT will provide a new therapeutic target for future drug or device development.

Original Source:

Home Search Introduction

Ken Teegardin - (Video)
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Welcome to the research tool. This tool is a searchable collection of technical publications, books, videos and other resources about the use of lasers for photobiomodulation. This tool includes almost the entire U.S. library of medicine research papers on LLLT, videos from Youtube associated with therapy lasers and the tables of contents from laser therapy books. This allows users to search for a keyword or condition and see resources about using lasers to treat that condition. All the resources include links to the original source so we are not making any statement about the use of lasers for treating non-FDA cleared application, we are simple summarizing what others have said.  Where every possible, we have included a link to the orginal publication.

Here are some of our favorite queries:

This tool uses a broad match query so:

  • It does not correct spelling and searches only cold laser related subjects so do not use LLLT, cold or laser in the search bar
  • It works better with shorter search terms or even parts of search terms
  • It searches all the available fields so you can enter a body part, author, condition or laser brand.
  • Where ever possible, the detailed section about the resource will link to the sources.
  • This system is only for photobiomodulation or cold laser therapy research (including LLLT, laser acupuncture and high power laser therapy) only. It does NOT include photodynamic laser therapy (where the laser is used to react with a pharmaceutical), hot surgery lasers or cosmetic lasers. It does include some resources on weight loss and smoking cessation.

The results of the search are sorted based on 3 quality factors on a scale of 1 to 10 with 10 being the best score. Originally all the resources were given a 5-5-5 until they could be individually evaluated. These scores are purely opinion and are only used to simplify the rank of the results from more valuable to least valuable. This should not be considered a critique of any work. This system was created to help researchers (including ourselves) find the most usable resources for any cold laser therapy research. The resources are assigned values based on the following 3 factors:

  • Efficacy: The resource (especially research papers) should show a significant improvement in the condition being treated. Resources that show better results are given a higher quality score.
  • Detail: The source must give enough information that the results can be duplicated. If a resource lacks too many details that it cannot be recreated, it is given a lower detail score.
  • Lack of Bias: Many resources are created to try and show that one device is superior to its competition. Many manufacturers have staff that crank out biased papers on a regular basis on the hope that this will make their product look superior. If the author of the resource is paid by a manufacturer of the resource appears to be biased towards one device and not one technology, the resource has much less value.

Over the past few years of working with research, we found that a majority of the published resources are lacking in one of these three ranking factors.
The original goal of this research tool was to tie published resources to the protocols in the library. This connection allows users to trace each protocol back to a list of resources so the protocol can be researched and improved.

General Comments

When many of the first research papers were published, the most power laser available for therapy were less than 100mW and many systems had to be pulsed to keep the laser from burning out too quickly. Today, system are available that will deliver up to 60,000mW of continuous output. Because of these power limitation, many early studies were limited to extremely low dosages by today’s standards. It takes a 50mW system 17 minutes to deliver 50 joules at the surface of the skin. If this was spread over a large area of damage or was treating a deeper problem, the actual dosages were much less than 1J/cm2.  Today, we know that these dosages typically produce very little or no results.
About 80% of the resources in this database are in the near infrared wavelength. There is also some interest in the red wavelength (600 to 660nm) . Other wavelengths like blue, purple, and green have very little scientific research behind them and have not gotten much traction in the core therapy market with the exception of some fringe consumer products.
Legal Disclaimer
This research tool is free to use but we make no claims about the accuracy of the information. It is an aggregation of existing published resources and it is up to the user to determine if the source of the resources has any value. The information provided through this web site should not be used for diagnosing or treating a health problem or disease. If you have or suspect you may have a health problem, you should consult your local health care provider.

The query result(s) can be shared using the following direct link. Anyone who clicks on this link in an email or on a web site will be shown the current results for the query.