Photobiomodulation for Global Cerebral Ischemia: Targeting Mitochondrial Dynamics and Functions.

Hypothermia is currently the only approved therapy for global cerebral ischemia (GCI) after cardiac arrest; however, it unfortunately has multiple adverse effects. As a noninvasive procedure, photobiomodulation (PBM) therapy has emerged as a potential novel treatment for brain injury. PBM involves the use of low-level laser light therapy to influence cell behavior. In this study, we evaluated the therapeutic effects of PBM treatment with an 808-nm diode laser initiated 6 h after GCI. It was noted that PBM dose-dependently protected against GCI-induced neuronal death in the vulnerable hippocampal CA1 subregion. Functional assessments demonstrated that PBM markedly preserved both short-term (a week) and long-term (6 months) spatial learning and memory function following GCI. Further mechanistic studies revealed that PBM post-treatment (a) preserved healthy mitochondrial dynamics and suppressed substantial mitochondrial fragmentation of CA1 neurons, by reducing the detrimental Drp1 GTPase activity and its interactions with adaptor proteins Mff and Fis1 and by balancing mitochondrial targeting fission and fusion protein levels; (b) reduced mitochondrial oxidative damage and excessive mitophagy and restored mitochondrial overall health status and preserved mitochondrial function; and (c) suppressed mitochondria-dependent apoptosome formation/caspase-3/9 apoptosis-processing activities. Additionally, we validated, in an in vitro ischemia model, that cytochrome c oxidase served as a key PBM target for mitochondrial function preservation and neuroprotection. Our findings suggest that PBM serves as a promising therapeutic strategy for the functional recovery after GCI, with mechanisms involving PBM's preservation on mitochondrial dynamics and functions and the inhibition of delayed apoptotic neuronal death in GCI.

[Effect of high frequency electrotherapy on caspase-3 and ultra microstructure of hippocampus in rats following cerebral ischemia/reperfusion].

OBJECTIVE: To investigate the effect of high frequency electrotherapy (HFE) on rat hippocampus after cerebral ischemia/reperfusion (I/R).
 Methods: A rat model of cerebral I/R injury was established. The rats were randomly divided into a sham group, an I/R group and an HFE group. The HFE group received thearapy daily for different sessions for 1, 3, 7 d. Neuronal deficit score,neuron ultra microstructure in the hippocampus and caspase-3 protein expression were measured on 1 st, 3 th and 7th d.
 Results: Compared with the I/R group, the HFE group showed the decreased neurological deficit scores, with significant differences between the 2 groups (P<0.05). The injury in HFE group was reduced compared with that in the I/R group based on the electron microscope test, with significant difference. Caspase-3 protein in brain tissue in the HFE group also downregulated compared with that in the I/R group (P<0.05).
 Conclusion: High frequency electrotherapy can improve neural function, suppress caspase-3 expression and apoptosis in nerve cells and improve the ultra microstructure of neurons, displaying a protective effect on cerebral I/R injury in rats.

Pre-conditioning with transcranial low-level light therapy reduces neuroinflammation and protects blood-brain barrier after focal cerebral ischemia in mice.

PURPOSE: Transcranial low-level light therapy (LLLT) has gained interest as a non-invasive, inexpensive and safe method of modulating neurological and psychological functions in recent years. This study was designed to examine the preventive effects of LLLT via visible light source against cerebral ischemia at the behavioral, structural and neurochemical levels. METHODS: The mice received LLLT twice a day for 2 days prior to photothrombotic cortical ischemia. RESULTS: LLLT significantly reduced infarct size and edema and improved neurological and motor function 24 h after ischemic injury. In addition, LLLT markedly inhibited Iba-1- and GFAP-positive cells, which was accompanied by a reduction in the expression of inflammatory mediators and inhibition of MAPK activation and NF-κB translocation in the ischemic cortex. Concomitantly, LLLT significantly attenuated leukocyte accumulation and infiltration into the infarct perifocal region. LLLT also prevented BBB disruption after ischemic events, as indicated by a reduction of Evans blue leakage and water content. These findings were corroborated by immunofluorescence staining of the tight junction-related proteins in the ischemic cortex in response to LLLT. CONCLUSIONS: Non-invasive intervention of LLLT in ischemic brain injury may provide a significant functional benefit with an underlying mechanism possibly being suppression of neuroinflammation and reduction of BBB disruption.

Effect of laser phototherapy on wound healing following cerebral ischemia by cryogenic injury.

Laser phototherapy emerges as an alternative or auxiliary therapy for acute ischemic stroke, traumatic brain injury, degenerative brain disease, spinal cord injury, and peripheral nerve regeneration, but its effects are still controversial. We have previously found that laser phototherapy immunomodulates the response to focal brain damage. Following direct cortical cryogenic injury the effects of laser phototherapy on inflammation and repair was assessed after cryogenic injury (CI) to the central nervous system (CNS) of rats. The laser phototherapy was carried out with a 780 nm AlGaAs diode laser. The irradiation parameters were: power of 40 mW, beam area of 0.04 cm(2), energy density of 3 J/cm(2) (3s) in two points (0.12 J per point). Two irradiations were performed at 3 h-intervals, in contact mode. Rats (20 non-irradiated - controls and 20 irradiated) were used. The wound healing in the CNS was followed in 6 h, 1, 7 and 14 days after the last irradiation. The size of the lesions, the neuron cell viability percentages and the amount of positive GFAP labeling were statistically compared by ANOVA complemented by Tukey's test (p<0.05). The distribution of lymphocytes, leukocytes and macrophages were also analyzed. CI created focal lesions in the cortex represented by necrosis, edema, hemorrhage and inflammatory infiltrate. The most striking findings were: lased lesions showed smaller tissue loss than control lesions in 6 h. During the first 24 h the amount of viable neurons was significantly higher in the lased group. There was a remarkable increase in the amount of GFAP in the control group by 14 days. Moreover, the lesions of irradiated animals had fewer leukocytes and lymphocytes in the first 24 h than controls. Considering the experimental conditions of this study it was concluded that laser phototherapy exerts its effect in wound healing following CI by controlling the brain damage, preventing neuron death and severe astrogliosis that could indicate the possibility of a better clinical outcome.

[Infrared cold laser radiation as an antimutagen].

Effects of infrared cold laser radiation (IRCLR) on mutagenesis and proliferation of the corneal epithelium were studied with laboratory white mice subjected to instigated circulatory hypoxia of the brain. The experiment was to reveal whether IRCLR influences the frequency of chromosomal rearrangements and to allow calculation of the corneal cells mitotic index for circulatory brain hypoxia. Laser radiation was shown to reconstitute the normal frequency of chromosomal aberrations as well as the mitotic cycle in epithelial cells of the mice cornea. Data of the experiment are promising from the standpoint of antihypoxic use of IRCLR in ophthalmology.

Effectiveness and safety of transcranial laser therapy for acute ischemic stroke.

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.

Infrared laser therapy for ischemic stroke: a new treatment strategy: results of the NeuroThera Effectiveness and Safety Trial-1 (NEST-1).

BACKGROUND AND PURPOSE: The NeuroThera Effectiveness and Safety Trial-1 (NEST-1) study evaluated the safety and preliminary effectiveness of the NeuroThera Laser System in the ability to improve 90-day outcomes in ischemic stroke patients treated within 24 hours from stroke onset. The NeuroThera Laser System therapeutic approach involves use of infrared laser technology and has shown significant and sustained beneficial effects in animal models of ischemic stroke. METHODS: This was a prospective, intention-to-treat, multicenter, international, double-blind, trial involving 120 ischemic stroke patients treated, randomized 2:1 ratio, with 79 patients in the active treatment group and 41 in the sham (placebo) control group. Only patients with baseline stroke severity measured by National Institutes of Health Stroke Scale (NIHSS) scores of 7 to 22 were included. Patients who received tissue plasminogen activator were excluded. Outcome measures were the patients' scores on the NIHSS, modified Rankin Scale (mRS), Barthel Index, and Glasgow Outcome Scale at 90 days after treatment. The primary outcome measure, prospectively identified, was successful treatment, documented by NIHSS. This was defined as a complete recovery at day 90 (NIHSS 0 to 1), or a decrease in NIHSS score of at least 9 points (day 90 versus baseline), and was tested as a binary measure (bNIH). Secondary outcome measures included mRS, Barthel Index, and Glasgow Outcome Scale. Primary statistical analyses were performed with the Cochran-Mantel-Haenszel rank test, stratified by baseline NIHSS score or by time to treatment for the bNIH and mRS. Logistic regression analyses were conducted to confirm the results. RESULTS: Mean time to treatment was >16 hours (median time to treatment 18 hours for active and 17 hours for control). Time to treatment ranged from 2 to 24 hours. More patients (70%) in the active treatment group had successful outcomes than did controls (51%), as measured prospectively on the bNIH (P=0.035 stratified by severity and time to treatment; P=0.048 stratified only by severity). Similarly, more patients (59%) had successful outcomes than did controls (44%) as measured at 90 days as a binary mRS score of 0 to 2 (P=0.034 stratified by severity and time to treatment; P=0.043 stratified only by severity). Also, more patients in the active treatment group had successful outcomes than controls as measured by the change in mean NIHSS score from baseline to 90 days (P=0.021 stratified by time to treatment) and the full mRS ("shift in Rankin") score (P=0.020 stratified by severity and time to treatment; P=0.026 stratified only by severity). The prevalence odds ratio for bNIH was 1.40 (95% CI, 1.01 to 1.93) and for binary mRS was 1.38 (95% CI, 1.03 to 1.83), controlling for baseline severity. Similar results held for the Barthel Index and Glasgow Outcome Scale. Mortality rates and serious adverse events (SAEs) did not differ significantly (8.9% and 25.3% for active 9.8% and 36.6% for control, respectively, for mortality and SAEs). CONCLUSIONS: The NEST-1 study indicates that infrared laser therapy has shown initial safety and effectiveness for the treatment of ischemic stroke in humans when initiated within 24 hours of stroke onset. A larger confirmatory trial to demonstrate safety and effectiveness is warranted.

Low-level laser therapy applied transcranially to rats after induction of stroke significantly reduces long-term neurological deficits.

BACKGROUND AND PURPOSE: Low-level laser therapy (LLLT) modulates various biological processes. In the present study, we assessed the hypothesis that LLLT after induction of stroke may have a beneficial effect on ischemic brain tissue. METHODS: Two sets of experiments were performed. Stroke was induced in rats by (1) permanent occlusion of the middle cerebral artery through a craniotomy or (2) insertion of a filament. After induction of stroke, a battery of neurological and functional tests (neurological score, adhesive removal) was performed. Four and 24 hours poststroke, a Ga-As diode laser was used transcranially to illuminate the hemisphere contralateral to the stroke at a power density of 7.5 mW/cm2. RESULTS: In both models of stroke, LLLT significantly reduced neurological deficits when applied 24 hours poststroke. Application of the laser at 4 hours poststroke did not affect the neurological outcome of the stroke-induced rats as compared with controls. There was no statistically significant difference in the stroke lesion area between control and laser-irradiated rats. The number of newly formed neuronal cells, assessed by double immunoreactivity to bromodeoxyuridine and tubulin isotype III as well as migrating cells (doublecortin immunoactivity), was significantly elevated in the subventricular zone of the hemisphere ipsilateral to the induction of stroke when treated by LLLT. CONCLUSIONS: Our data suggest that a noninvasive intervention of LLLT issued 24 hours after acute stroke may provide a significant functional benefit with an underlying mechanism possibly being induction of neurogenesis.