Far red/near infrared light-induced protection against cardiac ischemia and reperfusion injury remains intact under diabetic conditions and is independent of nitric oxide synthase

Modulation of mitochondrial function with near-infrared light reduces brain injury in a translational model of cardiac arrest

BACKGROUND

Brain injury is a leading cause of morbidity and mortality in patients resuscitated from cardiac arrest. Mitochondrial dysfunction contributes to brain injury following cardiac arrest; therefore, therapies that limit mitochondrial dysfunction have the potential to improve neurological outcomes. Generation of reactive oxygen species (ROS) during ischemia-reperfusion injury in the brain is a critical component of mitochondrial injury and is dependent on hyperactivation of mitochondria following resuscitation. Our previous studies have provided evidence that modulating mitochondrial function with specific near-infrared light (NIR) wavelengths can reduce post-ischemic mitochondrial hyperactivity, thereby reducing brain injury during reperfusion in multiple small animal models.

METHODS

Isolated porcine brain cytochrome c oxidase (COX) was used to investigate the mechanism of NIR-induced mitochondrial modulation. Cultured primary neurons from mice expressing mitoQC were utilized to explore the mitochondrial mechanisms related to protection with NIR following ischemia-reperfusion. Anesthetized pigs were used to optimize the delivery of NIR to the brain by measuring the penetration depth of NIR to deep brain structures and tissue heating. Finally, a model of out-of-hospital cardiac arrest with CPR in adult pigs was used to evaluate the translational potential of NIR as a noninvasive therapeutic approach to protect the brain after resuscitation.

RESULTS

Molecular evaluation of enzyme activity during NIR irradiation demonstrated COX function was reduced in an intensity-dependent manner with a threshold of enzyme inhibition leading to a moderate reduction in activity without complete inhibition. Mechanistic interrogation in neurons demonstrated that mitochondrial swelling and upregulation of mitophagy were reduced with NIR treatment. NIR therapy in large animals is feasible, as NIR penetrates deep into the brain without substantial tissue heating. In a translational porcine model of CA/CPR, transcranial NIR treatment for two hours at the onset of return of spontaneous circulation (ROSC) demonstrated significantly improved neurological deficit scores and reduced histologic evidence of brain injury after resuscitation from cardiac arrest.

CONCLUSIONS

NIR modulates mitochondrial function which improves mitochondrial dynamics and quality control following ischemia/reperfusion. Noninvasive modulation of mitochondria, achieved by transcranial treatment of the brain with NIR, mitigates post-cardiac arrest brain injury and improves neurologic functional outcomes.

Recent Mechanisms of Neurodegeneration and Photobiomodulation in the Context of Alzheimer's Disease

Alzheimer's disease (AD) is a neurodegenerative disease and the world's primary cause of dementia, a condition characterized by significant progressive declines in memory and intellectual capacities. While dementia is the main symptom of Alzheimer's, the disease presents with many other debilitating symptoms, and currently, there is no known treatment exists to stop its irreversible progression or cure the disease. Photobiomodulation has emerged as a very promising treatment for improving brain function, using light in the range from red to the near-infrared spectrum depending on the application, tissue penetration, and density of the target area. The goal of this comprehensive review is to discuss the most recent achievements in and mechanisms of AD pathogenesis with respect to neurodegeneration. It also provides an overview of the mechanisms of photobiomodulation associated with AD pathology and the benefits of transcranial near-infrared light treatment as a potential therapeutic solution. This review also discusses the older reports and hypotheses associated with the development of AD, as well as some other approved AD drugs.

Photobiomodulation therapy mitigates cardiovascular aging and improves survival

BACKGROUND

Photobiomodulation (PBM) therapy, a form of low-dose light therapy, has been noted to be effective in several age-associated chronic diseases such as hypertension and atherosclerosis. Here, we examined the effects of PBM therapy on age-associated cardiovascular changes in a mouse model of accelerated cardiac aging.

METHODS

Fourteen months old Adenylyl cyclase type VIII (AC8) overexpressing transgenic mice (n = 8) and their wild-type (WT) littermates (n = 8) were treated with daily exposure to Near-Infrared Light (850 nm) at 25 mW/cm2 for 2 min each weekday for a total dose of 1 Einstein (4.5 p.J/cm2 or fluence 3 J/cm2 ) and compared to untreated controls over an 8-month period. PBM therapy was administered for 3.5 months (Early Treatment period), paused, due to Covid-19 restrictions for the following 3 months, and restarted again for 1.5 months. Serial echocardiography and gait analyses were performed at monthly intervals, and serum TGF-β1 levels were assessed following sacrifice.

RESULTS

During the Early Treatment period PBM treatments: reduced the age-associated increases in left ventricular (LV) mass in both genotypes (p = 0.0003), reduced the LV end-diastolic volume (EDV) in AC8 (p = 0.04); and reduced the left atrial dimension in both genotypes (p = 0.02). PBM treatments substantially increased the LV ejection fraction (p = 0.03), reduced the aortic wall stiffness (p = 0.001), and improved gait symmetry, an index of neuro-muscular coordination (p = 0.005). The effects of PBM treatments, measured following the pause, persisted. Total TGF-β1 levels were significantly increased in circulation (serum) in AC8 following PBM treatments (p = 0.01). We observed a striking increase in cumulative survival in PBM-treated AC8 mice (100%; p = 0.01) compared to untreated AC8 mice (43%).

CONCLUSION

PBM treatment mitigated age-associated cardiovascular remodeling and reduced cardiac function, improved neuromuscular coordination, and increased longevity in an experimental animal model. These responses correlate with increased TGF-β1 in circulation. Future mechanistic and dose optimization studies are necessary to assess these anti-aging effects of PBM, and validation in future controlled human studies is required for effective clinical translation.

Photobiomodulation and nitric oxide signaling

Nitric oxide (NO) is a well-known gaseous mediator that maintains vascular homeostasis. Extensive evidence supports that a hallmark of endothelial dysfunction, which leads to cardiovascular diseases, is endothelial NO deficiency. Thus, restoring endothelial NO represents a promising approach to treating cardiovascular complications. Despite many therapeutic agents having been shown to augment NO bioavailability under various pathological conditions, success in resulting clinical trials has remained elusive. There is solid evidence of diverse beneficial effects of the treatment with low-power near-infrared (NIR) light, defined as photobiomodulation (PBM). Although the precise mechanisms of action of PBM are still elusive, recent studies consistently report that PBM improves endothelial dysfunction via increasing bioavailable NO in a dose-dependent manner and open a feasible path to the use of PBM for treating cardiovascular diseases via augmenting NO bioavailability. In particular, the use of NIR light in the NIR-II window (1000-1700 nm) for PBM, which has reduced scattering and minimal tissue absorption with the largest penetration depth, is emerging as a promising therapy. In this review, we update recent findings on PBM and NO.

Near-infrared II photobiomodulation augments nitric oxide bioavailability via phosphorylation of endothelial nitric oxide synthase

There is solid evidence of the beneficial effect of photobiomodulation (PBM) with low-power near-infrared (NIR) light in the NIR-I window in increasing bioavailable nitric oxide (NO). However, it is not established whether this effect can be extended to NIR-II light, limiting broader applications of this therapeutic modality. Since we have demonstrated PBM with NIR laser in the NIR-II window, we determined the causal relationship between NIR-II irradiation and its specific biological effects on NO bioavailability. We analyzed the impact of NIR-II irradiation on NO release in cultured human endothelial cells using a NO-sensitive fluorescence probe and single-cell live imaging. Two distinct wavelengths of NIR-II laser (1064 and 1270 nm) and NIR-I (808 nm) at an irradiance of 10 mW/cm2 induced NO release from endothelial cells. These lasers also enhanced Akt phosphorylation at Ser 473, endothelial nitric oxide synthase (eNOS) phosphorylation at Ser 1177, and endothelial cell migration. Moreover, the NO release and phosphorylation of eNOS were abolished by inhibiting mitochondrial respiration, suggesting that Akt activation caused by NIR-II laser exposure involves mitochondrial retrograde signaling. Other inhibitors that inhibit known Akt activation pathways, including a specific inhibitor of PI3K, Src family PKC, did not affect this response. These two wavelengths of NIR-II laser induced no appreciable NO generation in cultured neuronal cells expressing neuronal NOS (nNOS). In short, NIR-II laser enhances bioavailable NO in endothelial cells. Since a hallmark of endothelial dysfunction is suppressed eNOS with concomitant NO deficiency, NIR-II laser technology could be broadly used to restore endothelial NO and treat or prevent cardiovascular diseases.

Nitric Oxide Production and Regulation in the Teleost Cardiovascular System

Nitric Oxide (NO) is a free radical with numerous critical signaling roles in vertebrate physiology. Similar to mammals, in the teleost system the generation of sufficient amounts of NO is critical for the physiological function of the cardiovascular system. At the same time, NO amounts are strictly controlled and kept within basal levels to protect cells from NO toxicity. Changes in oxygen tension highly influence NO bioavailability and can modulate the mechanisms involved in maintaining the NO balance. While NO production and signaling appears to have general similarities with mammalian systems, the wide range of environmental adaptations made by fish, particularly with regards to differing oxygen availabilities in aquatic habitats, creates a foundation for a variety of in vivo models characterized by different implications of NO production and signaling. In this review, we present the biology of NO in the teleost cardiovascular system and summarize the mechanisms of NO production and signaling with a special emphasis on the role of globin proteins in NO metabolism.

Photobiomodulation Regulation as One Promising Therapeutic Approach for Myocardial Infarction

Myocardial infarction refers to myocardial necrosis caused by acute or persistent coronary ischemia and hypoxia. It is considered to be one of the significant crises threatening human health in the world. Following myocardial infarction, collagen gradually replaces the original tissue due to the loss of many cardiomyocytes, myocardial contractile function decreases, and myocardial fibrosis eventually leads to heart failure. Phototherapy is a new treatment which has shown superior efficacy on the nerve, skeletal muscle, skin, and other tissues. Likewise, there is growing evidence that phototherapy also has many positive effects on the heart. Therefore, this article introduces the progress of research on phototherapy as a new therapeutic strategy in the treatment of myocardial infarction. The wavelength of photobiomodulation in the treatment of myocardial infarction is specific, and the influence of light source power and light duration on the tissue presents a bell-shaped distribution. Under these conditions, phototherapy can promote ATP synthesis and angiogenesis, inhibit the inflammatory response, improve heart function, reduce infarct size, and protect myocardium. In addition, we summarized the molecular mechanisms of phototherapy. According to the location of photoreceptors, they can be divided into mitochondrial and nonmitochondrial parts.

What Lies at the Heart of Photobiomodulation: Light, Cytochrome C Oxidase, and Nitric Oxide-Review of the Evidence

Objective: The underlying mechanisms of photobiomodulation (PBM) remain elusive. The most attractive hypotheses revolve around the role of cytochrome c oxidase (CCO) and cellular energetics. Background: No reliable demonstration of any PBM-related light-induced mechanistic effect on CCO has been reported. Studies on PBM have proven to be either nonreproducible, of questionable relevance, or involve wavelengths unlikely to be operative in vivo. The literature reveals very few demonstrable mechanistic light effects of any sort on CCO. Nitric oxide (NO) is involved in a number of the reported light effects on CCO. NO inhibits CCO at high reductive pressures by binding to the heme a3 moiety. This complex is white light labile. Methods: The reported photolability of the heme-NO complex seems to be a prime target for PBM studies, as removal of inhibiting NO from the active site of CCO could restore normal activity to inhibited CCO. Another aspect of CCO-NO chemistry has been revealed that shows intriguing possibilities. Results: A novel nitrite reductase activity of solubilized mitochondria has been demonstrated attributable to CCO. NO production was optimal under hypoxic conditions. It was also found that 590 nm irradiation increased NO production by enhancing NO release. The presence of cellular NO has usually been considered metabolically detrimental, but current thinking has expanded the importance and the physiological roles of NO. Evidence shows that NO production is likely to play a role in cardioprotection and defenses against hypoxic damage. Conclusions: Studies combining PBM and hypoxia also point to a connection between light irradiation, hypoxia protection, and NO production. This leads the authors to the possibility that the intrinsic nature of PBM involves the production of NO. The combination of CCO and hemoglobin/myoglobin NO production with photorelease of NO may constitute the heart of PBM.

Transcranial Photobiomodulation For The Management Of Depression: Current Perspectives

Major depressive disorder (MDD) is a prevalent condition associated with high rates of disability, as well as suicidal ideation and behavior. Current treatments for MDD have significant limitations in efficacy and side effect burden. FDA-approved devices for MDD are burdensome (due to repeated in-office procedures) and are most suitable for severely ill subjects. There is a critical need for device-based treatments in MDD that are efficacious, well-tolerated, and easy to use. In this paper, we review a novel neuromodulation strategy, transcranial photobiomodulation (t-PBM) with near-infrared light (NIR). The scope of our review includes the known biological mechanisms of t-PBM, as well as its efficacy in animal models of depression and in patients with MDD. Theoretically, t-PBM penetrates into the cerebral cortex, stimulating the mitochondrial respiratory chain, and also significantly increases cerebral blood flow. Animal and human studies, using a variety of t-PBM settings and experimental models, suggest that t-PBM may have significant efficacy and good tolerability in MDD. In aggregate, these data support the need for large confirmatory studies for t-PBM as a novel, likely safe, and easy-to-administer antidepressant treatment.

Ascorbate attenuates red light mediated vasodilation: Potential role of S-nitrosothiols

There is significant therapeutic advantage of nitric oxide synthase (NOS) independent nitric oxide (NO) production in maladies where endothelium, and thereby NOS, is dysfunctional. Electromagnetic radiation in the red and near infrared region has been shown to stimulate NOS-independent but NO-dependent vasodilation, and thereby has significant therapeutic potential. We have recently shown that red light induces acute vasodilatation in the pre-constricted murine facial artery via the release of an endothelium derived substance. In this study we have investigated the mechanism of vasodilatation and conclude that 670 nm light stimulates vasodilator release from an endothelial store, and that this vasodilator has the characteristics of an S-nitrosothiol (RSNO). This study shows that 670 nm irradiation can be used as a targeted and non-invasive means to release biologically relevant amounts of vasodilator from endothelial stores. This raises the possibility that these stores can be pharmacologically built-up in pathological situations to improve the efficacy of red light treatment. This strategy may overcome eNOS dysfunction in peripheral vascular pathologies for the improvement of vascular health.

Cardio-light: nitric oxide uncaged

Photobiomodulation (PB) is a utilization of low-level laser therapy (LLLT) in the far red (R) to near infrared (NIR) spectrum (600-1000 nm) to wield its therapeutic effects. To explore the therapeutic potential of biomodulation of different tissues, LLLT has been extensively researched, especially in the light of its very low side effect profile. We believe there is an opportunity to unearth its dynamic effects on the coronaries which can be promising for the patients with chronic stable angina. NIR treatment of the heart may be protective on patients after acute myocardial infarction or on ischemic heart conditions that are not accessible to current revascularization procedures.

Wavelength-dependence of vasodilation and NO release from S-nitrosothiols and dinitrosyl iron complexes by far red/near infrared light

Far red/near infrared (R/NIR) energy is a novel therapy, but its mechanism of action is poorly characterized. Cytochrome c oxidase (Cco) of the mitochondrial electron transport chain is considered the primary photoacceptor for R/NIR to photolyze a putative heme nitrosyl in Cco to liberate free nitric oxide (NO). We previously observed R/NIR light directly liberates NO from nitrosylated hemoglobin and myoglobin, and recently suggested S-nitrosothiols (RSNO) and dinitrosyl iron complexes (DNIC) may be primary sources of R/NIR-mediated NO. Here we indicate R/NIR light exposure induces wavelength dependent dilation of murine facial artery, with longer wavelengths (740, and 830 nm) exhibiting reduced potency when compared to 670 nm. R/NIR also stimulated NO release from pure solutions of low molecular weight RSNO (GSNO and SNAP) and glutathione dinitrosyl iron complex (GSH-DNIC) in a power- and wavelength-dependent manner, with the greatest effect at 670 nm. NO release from SNAP using 670 was nearly ten-fold more than GSNO or GSH-DNIC, with no substantial difference in NO production at 740 nm and 830 nm. Thermal effects of irradiation on vasodilation or NO release from S-nitrosothiols and DNIC was minimal. Our results suggest 670 nm is the optimal wavelength for R/NIR treatment of certain vascular-related diseases.

Myocyte membrane and microdomain modifications in diabetes: determinants of ischemic tolerance and cardioprotection

Cardiovascular disease, predominantly ischemic heart disease (IHD), is the leading cause of death in diabetes mellitus (DM). In addition to eliciting cardiomyopathy, DM induces a ‘wicked triumvirate’: (i) increasing the risk and incidence of IHD and myocardial ischemia; (ii) decreasing myocardial tolerance to ischemia–reperfusion (I–R) injury; and (iii) inhibiting or eliminating responses to cardioprotective stimuli. Changes in ischemic tolerance and cardioprotective signaling may contribute to substantially higher mortality and morbidity following ischemic insult in DM patients. Among the diverse mechanisms implicated in diabetic impairment of ischemic tolerance and cardioprotection, changes in sarcolemmal makeup may play an overarching role and are considered in detail in the current review. Observations predominantly in animal models reveal DM-dependent changes in membrane lipid composition (cholesterol and triglyceride accumulation, fatty acid saturation vs. reduced desaturation, phospholipid remodeling) that contribute to modulation of caveolar domains, gap junctions and T-tubules. These modifications influence sarcolemmal biophysical properties, receptor and phospholipid signaling, ion channel and transporter functions, contributing to contractile and electrophysiological dysfunction, cardiomyopathy, ischemic intolerance and suppression of protective signaling. A better understanding of these sarcolemmal abnormalities in types I and II DM (T1DM, T2DM) can inform approaches to limiting cardiomyopathy, associated IHD and their consequences. Key knowledge gaps include details of sarcolemmal changes in models of T2DM, temporal patterns of lipid, microdomain and T-tubule changes during disease development, and the precise impacts of these diverse sarcolemmal modifications. Importantly, exercise, dietary, pharmacological and gene approaches have potential for improving sarcolemmal makeup, and thus myocyte function and stress-resistance in this ubiquitous metabolic disorder.

Improving mitochondrial function significantly reduces metabolic, visual, motor and cognitive decline in aged Drosophila melanogaster

Mitochondria play a major role in aging. Over time, mutations accumulate in mitochondrial DNA leading to reduced adenosine triphosphate (ATP) production and increased production of damaging reactive oxygen species. If cells fail to cope, they die. Reduced ATP will result in declining cellular membrane potentials leading to reduced central nervous system function. However, aged mitochondrial function is improved by long wavelength light (670 nm) absorbed by cytochrome c oxidase in mitochondrial respiration. In Drosophila, lifelong 670-nm exposure extends lifespan and improves aged mobility. Here, we ask if improved mitochondrial metabolism can reduce functional senescence in metabolism, sensory, locomotor, and cognitive abilities in old flies exposed to 670 nm daily for 1 week. Exposure significantly increased cytochrome c oxidase activity, whole body energy storage, ATP and mitochondrial DNA content, and reduced reactive oxygen species. Retinal function and memory were also significantly improved to levels found in 2-week-old flies. Mobility improved by 60%. The mode of action is likely related to improved energy homeostasis increasing ATP availability for ionic ATPases critical for maintenance of neuronal membrane potentials. 670-nm light exposure may be a simple route for resolving problems of aging.

Photostimulation of mitochondria as a treatment for retinal neurodegeneration

Absorption of photon energy by neuronal mitochondria leads to numerous downstream neuroprotective effects. Red and near infrared (NIR) light are associated with significantly less safety concerns than light of shorter wavelengths and they are therefore, the optimal choice for irradiating the retina. Potent neuroprotective effects have been demonstrated in various models of retinal damage, by red/NIR light, with limited data from human studies showing its ability to improve visual function. Improved neuronal mitochondrial function, increased blood flow to neural tissue, upregulation of cell survival mediators and restoration of normal microglial function have all been proposed as potential underlying mechanisms of red/NIR light.

A new path in defining light parameters for hair growth: Discovery and modulation of photoreceptors in human hair follicle

BACKGROUND AND OBJECTIVE

Though devices for hair growth based on low levels of light have shown encouraging results, further improvements of their efficacy is impeded by a lack of knowledge on the exact molecular targets that mediate physiological response in skin and hair follicle. The aim of this study was to investigate the expression of selected light-sensitive receptors in the human hair follicle and to study the impact of UV-free blue light on hair growth ex vivo.

MATERIAL AND METHODS

The expression of Opsin receptors in human skin and hair follicles has been characterized using RT-qPCR and immunofluorescence approaches. The functional significance of Opsin 3 was assessed by silencing its expression in the hair follicle cells followed by a transcriptomic profiling. Proprietary LED-based devices emitting two discrete visible wavelengths were used to access the effects of selected optical parameters on hair growth ex vivo and outer root sheath cells in vitro.

RESULTS

The expression of OPN2 (Rhodopsin) and OPN3 (Panopsin, Encephalopsin) was detected in the distinct compartments of skin and anagen hair follicle. Treatment with 3.2 J/cm² of blue light with 453 nm central wavelength significantly prolonged anagen phase in hair follicles ex vivo that was correlated with sustained proliferation in the light-treated samples. In contrast, hair follicle treatment with 3.2 J/cm² of 689 nm light (red light) did not significantly affect hair growth ex vivo. Silencing of OPN3 in the hair follicle outer root sheath cells resulted in the altered expression of genes involved in the control of proliferation and apoptosis, and abrogated stimulatory effects of blue light (3.2 J/cm² ; 453 nm) on proliferation in the outer root sheath cells.

CONCLUSIONS

We provide the first evidence that (i) OPN2 and OPN3 are expressed in human hair follicle, and (ii) A 453 nm blue light at low radiant exposure exerts a positive effect on hair growth ex vivo, potentially via interaction with OPN3. Lasers Surg. Med. 49:705-718, 2017. © 2017 Wiley Periodicals, Inc.

A Role for Photobiomodulation in the Prevention of Myocardial Ischemic Reperfusion Injury: A Systematic Review and Potential Molecular Mechanisms

Myocardial ischemia reperfusion injury is a negative pathophysiological event that may result in cardiac cell apoptosis and is a result of coronary revascularization and cardiac intervention procedures. The resulting loss of cardiomyocyte cells and the formation of scar tissue, leads to impaired heart function, a major prognostic determinant of long-term cardiac outcomes. Photobiomodulation is a novel cardiac intervention that has displayed therapeutic effects in reducing myocardial ischemia reperfusion related myocardial injury in animal models. A growing body of evidence supporting the use of photobiomodulation in myocardial infarct models has implicated multiple molecular interactions. A systematic review was conducted to identify the strength of the evidence for the therapeutic effect of photobiomodulation and to summarise the current evidence as to its mechanisms. Photobiomodulation in animal models showed consistently positive effects over a range of wavelengths and application parameters, with reductions in total infarct size (up to 76%), decreases in inflammation and scarring, and increases in tissue repair. Multiple molecular pathways were identified, including modulation of inflammatory cytokines, signalling molecules, transcription factors, enzymes and antioxidants. Current evidence regarding the use of photobiomodulation in acute and planned cardiac intervention is at an early stage but is sufficient to inform on clinical trials.

Photobiomodulation devices for hair regrowth and wound healing: a therapy full of promise but a literature full of confusion

Photobiomodulation is reported to positively influence hair regrowth, wound healing, skin rejuvenation and psoriasis. Despite rapid translation of this science to commercial therapeutic solutions, significant gaps in our understanding of the underlying processes remain. The aim of this review was to seek greater clarity and rationality specifically for the selection of optical parameters for studies on hair regrowth and wound healing. Our investigation of 90 reports published between 1985 and 2015 revealed major inconsistencies in optical parameters selected for clinical applications. Moreover, poorly understood photoreceptors expressed in skin such as cytochrome c oxidase, cryptochromes, opsins etc. may trigger different molecular mechanisms. All this could explain the plethora of reported physiological effects of light. To derive parameters for optimal clinical efficacy of photobiomodulation, we recommend a more rational approach to underpin clinical studies, with research on molecular targets and pathways using well-defined biological model systems to enable translation of optical parameters from in vitro to in vivo. Furthermore, special attention needs to be paid when conducting studies for hair regrowth, aiming for double-blind, placebo-controlled randomized clinical trials as the gold standard for quantifying hair growth.

Low-level laser irradiation effect on endothelial cells under conditions of hyperglycemia

Diabetes mellitus is considered to be a very serious lifestyle disease leading to cardiovascular complications and impaired wound healing observed in the diabetic foot syndrome. Chronic hyperglycemia is the source of the endothelial activation. The inflammatory process in diabetes is associated with the secretion of inflammatory cytokines by endothelial cells, e.g., tumor necrosis factor-alpha (TNF-α) and interleukin 6 (IL-6). The method of phototherapy using laser beam of low power (LLLT-low-level laser therapy) effectively supports the conventional treatment of diabetic vascular complications such as diabetic foot syndrome. The aim of our study was to evaluate the effect of low-power laser irradiation at two wavelengths (635 and 830 nm) on the secretion of inflammatory factors (TNF-α and IL-6) by the endothelial cell culture-HUVEC line (human umbilical vein endothelial cell)-under conditions of hyperglycemia. It is considered that adverse effects of hyperglycemia on vascular endothelial cells may be corrected by the action of LLLT, especially with the wavelength of 830 nm. It leads to the reduction of TNF-α concentration in the supernatant and enhancement of cell proliferation. Endothelial cells play an important role in the pathogenesis of diabetes; however, a small number of studies evaluate an impact of LLLT on these cells under conditions of hyperglycemia. Further work on this subject is warranted.

Neuroprotective Effects Against POCD by Photobiomodulation: Evidence from Assembly/Disassembly of the Cytoskeleton

Postoperative cognitive dysfunction (POCD) is a decline in memory following anaesthesia and surgery in elderly patients. While often reversible, it consumes medical resources, compromises patient well-being, and possibly accelerates progression into Alzheimer's disease. Anesthetics have been implicated in POCD, as has neuroinflammation, as indicated by cytokine inflammatory markers. Photobiomodulation (PBM) is an effective treatment for a number of conditions, including inflammation. PBM also has a direct effect on microtubule disassembly in neurons with the formation of small, reversible varicosities, which cause neural blockade and alleviation of pain symptoms. This mimics endogenously formed varicosities that are neuroprotective against damage, toxins, and the formation of larger, destructive varicosities and focal swellings. It is proposed that PBM may be effective as a preconditioning treatment against POCD; similar to the PBM treatment, protective and abscopal effects that have been demonstrated in experimental models of macular degeneration, neurological, and cardiac conditions.