Photobiomodulation induces in vitro re-epithelialization via nitric oxide production

Efficacy and Safety of Visible and Near-Infrared Photobiomodulation Therapy on Astenospermic Human Sperm: Wavelength-Dependent Regulation of Nitric Oxide Levels and Mitochondrial Energetics

Male infertility is a growing global concern, with asthenozoospermia being an important contributing factor. Mitochondrial dysfunction and changes in the metabolism of nitric oxide (NO) are key determinants of reduced sperm motility. This study investigates the effects of photobiomodulation (PBM) with visible and near-infrared (NIR) laser light on sperm of asthenozoospermic patients, focusing on mitochondrial energetic status, oxidative stress, and NO dynamics. Semen samples were irradiated at 450 nm, 635 nm, 810 nm, 940 nm, and 1064 nm at different power levels (0.25, 0.50, 1.00, and 2.00 W) for 60 s on a spot area of 1 cm2. ATP and AMP levels, oxidative stress markers, and NO concentrations were assessed at 10 and 60 min after irradiation, with the ATP/AMP ratio calculated as an index of cellular energy balance. The results show that the PBM modulates the energetic status of spermatozoa in a way dependent on wavelength and dose. Irradiation at 810 nm produced the most marked improvement in energetic status, whereas 635 nm exposure led to a significant decrease in cellular energy levels. NO levels showed a biphasic response, correlated with the visible range and with energy metabolism at 810 nm. Irradiation with 635 nm induced higher NO production with respect to the other wavelengths. Our findings suggest that PBM mainly involves mitochondrial photoreceptors and potentially the heme and flavin groups of nitric oxide synthases, facilitating electron transitions, enhancing the effectiveness of oxidative phosphorylation, and optimizing enzymatic activity. At longer wavelengths (940 nm and 1064 nm), interactions with water and lipids may introduce additional variables that affect membrane fluidity and mitochondrial function differently from shorter wavelengths.

Engineering Mild-Photothermal Responsive and NO Donor Prussian Blue Nanozymes Using Mild Synthesis for Inflammation Regulation and Bacterial Eradication in Periodontal Disease

Periodontitis, an infectious disease of periodontal tissues caused by oral bacterial biofilms, is characterized by reactive oxygen species (ROS) accumulation and immune microenvironment imbalance. Multifunctional nanozymes, leveraging their physiochemical properties and enzymatic activities, offer promising antibacterial and anti-inflammatory strategies for managing periodontitis. In particular, Prussian blue nanozymes (PBzymes) exhibit exceptional ROS control due to their robust catalytic activity, diverse antioxidant functions, and high biocompatibility. However, the practical application of traditional high-temperature synthesis methods is limited. This study introduces a class of metal-engineered PBzymes synthesized at room temperature, identified for their potent antioxidative activity and excellent photothermal performance at mild temperatures. Nitric oxide (NO) gas therapy offers promising strategies for targeting deep infections in periodontal tissues. Thus, sodium nitroprusside is introduced into PBzyme to create SPBzyme via an in situ loading method. NO release by SPBzyme enhances antibacterial effects and overcomes resistance linked to bacterial biofilms, resulting in mild-photothermal antibacterial properties and synergistic antioxidant effects. In vitro antibacterial assays demonstrate the superior efficacy of SPBzyme under mild temperature conditions and near-infrared light exposure. Furthermore, SPBzyme effectively reduces inflammation and has positive therapeutic effects in periodontal animal models. Overall, mild-temperature photothermal NO release nanozyme therapy represents a novel approach for treating periodontitis.

The Application of Photobiomodulation on Mesenchymal Stem Cells and its Potential Use for Tenocyte Differentiation

Tendinopathy is a prevalent and debilitating musculoskeletal disorder. Uncertainty remains regarding its pathophysiology, but it is believed to be a combination of inflammation, damage, degenerative changes, and unsuccessful repair mechanisms. Cell-based therapy is an emerging regenerative medicine modality that uses mesenchymal stem cells (MSCs), their progeny or exosomes to promote tendon healing and regeneration. It is based on the fact that MSCs can be differentiated into tenocytes, the major cell type within tendons, and facilitate tendon repair. Photobiomodulation (PBM) is a non-invasive and potentially promising therapeutic technique that utilizes low-level light to alter intracellular processes and promote tissue healing and regeneration. Recent studies have examined the potential for PBM to improve MSC therapy use in tendinopathy by promoting viability, proliferation, and differentiation. As well as enhance tendon regeneration. This review focuses on Photobiomodulation and MSC therapy applications in regenerative medicine and their potential for tendon tissue engineering.

The Efficacy of Er:YAG Laser in the Extraction of Impacted Third Molars: A Randomized Clinical Trial

(1) Background: Impacted third molar extraction with a scalpel and rotary instruments is one of the most traumatic surgeries in dentistry. Therefore, it is necessary to discover less traumatic methods and instruments to reduce the risk of postoperative complications. (2) Methods: This study is reported in accordance with the CONSORT guidelines. The study aim is to assess the effectiveness of an Er:YAG laser with a wavelength of 2.94 μm, cutting and rotating instruments in the extraction of lower third molars in comparison with the traditional instruments using clinical and radiology parameters. In the control group, the impacted third molars were extracted with the traditional instruments, like scalpel and rotary instruments; in the test group, the impacted third molars were extracted with an Er:YAG laser. As per the inclusion and exclusion criteria, we enrolled 60 patients who were randomly assigned into two groups (Er:YAG laser group and control group). The efficacy of the Er:YAG laser was assessed by postoperative pain, collateral swelling, mouth opening, and radiology parameters such as radiographic infrabony defects and radiographic bone height after tooth extraction. (3) Results: The results showed that the clinical postoperative parameters like pain, collateral swelling, and mouth opening were less pronounced in the Er:YAG laser group than those in the control group (p < 0.001). According to the data of the radiology parameters (RBH and RID), the regeneration of the socket after extraction was better in the laser group than in the control group (p < 0.001). (4) Conclusions: Based on the obtained results of clinical and radiology parameters assessment, it was shown that third molar extraction using an Er:YAG laser is a less traumatic method than extraction using a scalpel and rotary instruments.

Photobiomodulation CME part I: Overview and mechanism of action

Photobiomodulation (PBM), previously known as low-level laser light therapy, represents a noninvasive form of phototherapy that utilizes wavelengths in the red light (RL, 620-700 nm) portion of the visible light (VL, 400-700 nm) spectrum and the near-infrared (NIR, 700-1440 nm) spectrum. PBM is a promising and increasingly used therapy for the treatment of various dermatologic and nondermatologic conditions. Photons from RL and NIR are absorbed by endogenous photoreceptors including mitochondrial cytochrome C oxidase (COX). Activation of COX leads to the following changes: modulation of mitochondrial adenosine triphosphate (ATP), generation of reactive oxygen species (ROS), and alterations in intracellular calcium levels. The associated modulation of ATP, ROS and calcium levels promotes the activation of various signaling pathways (eg, insulin-like growth factors, phosphoinositide 3-kinase pathways), which contribute to downstream effects on cellular proliferation, migration, and differentiation. Effective PBM therapy is dependent on treatment parameters (eg, fluence, treatment duration and output power). PBM is generally well-tolerated and safe with erythema being the most common and self-limiting adverse cutaneous effect.

Effect of photobiomodulation in an experimental in vitro model of asthma-Copd overlap

The objective of the study was to evaluate the effect of photobiomodulation (PBM) with laser on the inflammatory process in an experimental in vitro model of ACO. The groups were: (1) human bronchial epithelial cells (BEAS-2B); (2) BEAS-2B cells treated with dexamethasone; (3) BEAS-2B cells irradiated with laser; (4) BEAS-2B cells stimulated with cigarette smoke extract (CSE) + House Dust Mite (HDM); (5) BEAS-2B cells stimulated with CSE + HDM and treated with dexamethasone; (6) BEAS-2B cells incubated with CSE + HDM and irradiated with laser. After 24 h, cytokines were quantified. There was a reduction in TNF-α, IL-1β, IL-6, IL-4, IL-5, IL-13, IL-17, IL-21, IL-23, and an increase in IL-10 and IFN-γ in cells from the laser-irradiated ACO group compared to only ACO group. With these results, we can suggest that photobiomodulation acts in the modulation of inflammation observed in ACO, and may be a treatment option.

Laser Biostimulation Induces Wound Healing-Promoter β2-Defensin Expression in Human Keratinocytes via Oxidative Stress

The innate immune system is the first line of defense of the body composed of anatomical barriers, such as skin and mucosa, as well as effector cells, antimicrobial peptides, soluble mediators, and cell receptors able to detect and destroy viruses and bacteria and to sense trauma and wounds to initiate repair. The human β-defensins belong to a family of antimicrobial small cationic peptides produced by epithelial cells, and show immunomodulatory and pro-healing activities. Laser biostimulation is a therapy widely used to contrast microbial infection and to accelerate wound healing through biological mechanisms that include the creation of oxidative stress. In this paper, we explored laser biostimulation's ability to modulate the production of two β-defensins, hBD-1 and hBD-2, in human keratinocytes and whether this modulation was, at least in part, oxidative-stress-dependent. Human spontaneously immortalized keratinocytes (HaCaT) were stimulated using laser irradiation at a 980 nm wavelength, setting the power output to 1 W (649.35 mW/cm2) in the continuous mode. Cells were irradiated for 0 (negative control), 5, 10, 25 and 50 s, corresponding to an energy stimulation of 0, 5, 10, 25 and 50 J. Positive control cells were treated with lipopolysaccharide (LPS, 200 ng/mL). After 6 and 24 h of treatment, the cell conditioned medium was collected and analyzed via ELISA assay for the production of hBD-1 and hBD-2. In another set of experiments, HaCaT were pre-incubated for 45 min with antioxidant drugs-vitamin C (Vit. C, 100 µM), sodium azide (NaN3, 1 mM); ω-nitro-L-arginine methyl ester (L-NAME, 10 mM) and sodium pyruvate (NaPyr, 100 µM)-and then biostimulated for 0 or 50 s. After 6 h, the conditioned medium was collected and used for the ELISA analysis. The hBD-1 and hBD-2 production by HaCaT was significantly increased by single laser biostimulation after 6 h in an energy-dependent fashion compared to basal levels, and both reached production levels induced by LPS. After 24 h, only hBD-2 production induced by laser biostimulation was further increased, while the basal and stimulated hBD-1 levels were comparable. Pre-incubation with antioxidative drugs was able to completely abrogate the laser-induced production of both hBD-1 and hBD-2 after 6 h, with the exception of hBD-1 production in samples stimulated after NaN3 pre-incubation. A single laser biostimulation induced the oxidative-stress-dependent production of both hBD-1 and hBD-2 in human keratinocytes. In particular, the pro-healing hBD-2 level was almost three times higher than the baseline level and lasted for 24 h. These findings increase our knowledge about the positive effects of laser biostimulation on wound healing.

An injectable multifunctional hydrogel for eradication of bacterial biofilms and wound healing

Wound treatment is largely influenced by pre-existing hypoxic microenvironments and biofilms, which can severely diminish the efficacy of phototherapy, suggesting the importance of multifunctional nanoplatforms for synergistic treatment of wound infections. Here, we developed a multifunctional injectable hydrogel (PSPG hydrogel) by loading photothermal sensitive sodium nitroprusside (SNP) into Pt-modified porphyrin metal organic framework (PCN) and in situ modification of gold particles to form a near-infrared (NIR) light-triggered all-in-one phototherapeutic nanoplatform. The Pt-modified nanoplatform exhibits a remarkable catalase-like behavior and promotes the continuous decomposition of endogenous H₂O₂ into O₂, thereby enhancing the photodynamic therapy (PDT) effect under hypoxia. Under dual NIR irradiation, PSPG hydrogel can not only produce hyperthermia (η=89.21%) but also generate reactive oxygen species and trigger NO release, contributing jointly to removal of biofilms and disruption of the cell membranes of methicillin-resistant Staphylococcus aureus (MRSA) and Escherichia coli (E. coli). In vivo experiments demonstrated a 99.9% reduction in bacterial burden on wounds. Additionally, PSPG hydrogel can accelerate MRSA-infected and Pseudomonas aeruginosa-infected (P. aeruginosa-infected) wound healing by promoting angiogenesis, collagen deposition, and suppressing inflammatory responses. Furthermore, in vitro and in vivo experiments revealed that PSPG hydrogel has good cytocompatibility. Overall, we proposed an antimicrobial strategy to eliminate bacteria through the synergistic effects of gas-photodynamic-photothermal killing, alleviating hypoxia in the bacterial infection microenvironment, and inhibiting biofilms, offering a new way against antimicrobial resistance and biofilm-associated infections. STATEMENT OF SIGNIFICANCE: The NIR light-triggered multifunctional injectable hydrogel nanoplatform (PSPG hydrogel) based on Pt-decorated gold nanoparticles with sodium nitroprusside (SNP)-loading porphyrin metal organic framework (PCN) as inner templates can efficiently perform photothermal conversion (η=89.21%) to trigger NO release from SNP, while continuously regulating the hypoxic microenvironment at the bacterial infection site through Pt-induced self-oxygenation, achieving efficient sterilization and removal of biofilm by synergistic PDT and PTT phototherapy. In vivo and in vitro experiments demonstrated that the PSPG hydrogel has significant anti-biofilm, antibacterial, and inflammatory regulatory functions. This study proposed an antimicrobial strategy to eliminate bacteria through the synergistic effects of gas-photodynamic-photothermal killing, alleviating hypoxia in the bacterial infection microenvironment, and inhibiting biofilms.

Enhancement of Nitric Oxide Bioavailability by Modulation of Cutaneous Nitric Oxide Stores

The generation of nitric oxide (NO) in the skin plays a critical role in wound healing and the response to several stimuli, such as UV exposure, heat, infection, and inflammation. Furthermore, in the human body, NO is involved in vascular homeostasis and the regulation of blood pressure. Physiologically, a family of enzymes termed nitric oxide synthases (NOS) generates NO. In addition, there are many methods of non-enzymatic/NOS-independent NO generation, e.g., the reduction of NO derivates (NODs) such as nitrite, nitrate, and nitrosylated proteins under certain conditions. The skin is the largest and heaviest human organ and contains a comparatively high concentration of these NODs; therefore, it represents a promising target for many therapeutic strategies for NO-dependent pathological conditions. In this review, we give an overview of how the cutaneous NOD stores can be targeted and modulated, leading to a further accumulation of NO-related compounds and/or the local and systemic release of bioactive NO, and eventually, NO-related physiological effects with a potential therapeutical use for diseases such as hypertension, disturbed microcirculation, impaired wound healing, and skin infections.

Enhancement of Frequency-Specific Hemodynamic Power and Functional Connectivity by Transcranial Photobiomodulation in Healthy Humans

Transcranial photobiomodulation (tPBM) has been considered a safe and effective brain stimulation modality being able to enhance cerebral oxygenation and neurocognitive function. To better understand the underlying neurophysiological effects of tPBM in the human brain, we utilized a 111-channel functional near infrared spectroscopy (fNIRS) system to map cerebral hemodynamic responses over the whole head to 8-min tPBM with 1,064-nm laser given on the forehead of 19 healthy participants. Instead of analyzing broad-frequency hemodynamic signals (0–0.2 Hz), we investigated frequency-specific effects of tPBM on three infra-slow oscillation (ISO) components consisting of endogenic, neurogenic, and myogenic vasomotions. Significant changes induced by tPBM in spectral power of oxygenated hemoglobin concentration (Δ[HbO]), functional connectivity (FC), and global network metrics at each of the three ISO frequency bands were identified and mapped topographically for frequency-specific comparisons. Our novel findings revealed that tPBM significantly increased endogenic Δ[HbO] powers over the right frontopolar area near the stimulation site. Also, we demonstrated that tPBM enabled significant enhancements of endogenic and myogenic FC across cortical regions as well as of several global network metrics. These findings were consistent with recent reports and met the expectation that myogenic oscillation is highly associated with endothelial activity, which is stimulated by tPBM-evoked nitric oxide (NO) release.

Stimulatory responses in α- and β-cells by near-infrared (810 nm) photobiomodulation

Significant efforts have been committed to better understand and regulate insulin secretion as it has direct implications on diabetes. The first phase of biphasic insulin secretion in response to glucose lasts about 10 minutes, followed by a more sustained release persisting several hours. Attenuated insulin release in the first phase is typically associated with abnormal β-cells. While near-infrared photobiomodulation (PBM) demonstrates potential for multiple therapeutic applications, photostimulatory effects on α- and β-cells remain to be further elucidated. Herein, we demonstrate that 810 nm PBM exposure at fluence of 9 J/cm² can elevate the intracellular reactive oxygen species within 15 minutes following photostimulation. In addition, calcium spiking showed an approximately 3-fold increase in both ATC1 (α-cells) and BTC6 (β-cells) and correlates with hormone secretion in response to PBM stimulation. Our findings could lay a foundation for the development of non-biologic therapeutics that can augment islet transplantation.

Blue Laser Irradiation Decreases the ATP Level in Mouse Skin and Increases the Production of Superoxide Anion and Hypochlorous Acid in Mouse Fibroblasts

Simple Summary

Photobiomodulation studies have reported that blue light irradiation induces the production of reactive oxygen species. We examined the effect of blue laser (405 nm) irradiation on ATP level in the skin and measured the types of reactive oxygen species and reactive nitrogen species. The decrease in the skin ATP level due to blue light irradiation may be caused by oxidative stress due to the generation of reactive oxygen species. These findings highlight the need to consider the effects on the skin when performing photobiomodulation treatment using blue light.

Abstract

Photobiomodulation studies have reported that blue light irradiation induces the production of reactive oxygen species. We investigated the effect of blue laser (405 nm) irradiation on the ATP levels in mouse skin and determined the types of reactive oxygen species and reactive nitrogen species using cultured mouse fibroblasts. Blue laser irradiation caused a decrease in the ATP level in the mouse skin and triggered the generation of superoxide anion and hypochlorous acid, whereas nitric oxide and peroxynitrite were not detected. Moreover, blue laser irradiation resulted in reduced cell viability. It is believed that the decrease in the skin ATP level due to blue light irradiation results from the increased levels of oxidative stress due to the generation of reactive oxygen species. This method of systematically measuring the levels of reactive oxygen species and reactive nitrogen species may be useful for understanding the effects of irradiation conditions.

Photobiomodulation therapy was more effective than photobiomodulation plus arginine on accelerating wound healing in an animal model of delayed healing wound

The combined and individual influences of photobiomodulation therapy (PBMT) and arginine on wound strength, stereological parameters, and gene expressions of some related growth factors in ischemic and delayed healing wounds in rats were analyzed. We divided 108 rats into six groups: control, lower energy density (LOW)-PBMT, 2% arginine ointment (Arg 2%), LOW-PBMT + Arg 2%, high energy density (HIGH)-PBMT, and HIGH-PBMT + Arg 2%. First, we generated an ischemic and delayed healing wound model in each rat. We examined wound strength, stereological parameters, and gene expressions of basic fibroblast growth factor (bFGF), vascular endothelial growth factor A (VEGF-A), and stromal cell-derived factor 1 (SDF-1) by quantitative real-time polymerase chain reaction (qRT-PCR). PBMT alone and PBMT + Arg 2% considerably increased wound strength compared to the control and Arg 2% groups during the inflammatory and proliferative steps of wound healing (p < 0.05). In these steps, PBMT alone significantly induced an anti-inflammatory effect and increased fibroblast counts; Arg 2% alone induced an inflammatory response (p < 0.05). Concurrently, PBMT and PBMT + Arg 2% significantly increased keratinocyte counts and volume of the new dermis (p < 0.05). At the remodeling step, the Arg 2% groups had significantly better wound strength than the other groups (p < 0.05). In this step, PBMT and PBMT + Arg 2% significantly decreased inflammation, and increased fibroblast counts, vascular length, and the volume of new epidermis and dermis compared to the control and Arg 2% groups (p < 0.05). In all cases of gene analysis, there were statistically better results in the PBMT and PBMT + Arg 2% groups compared with the Arg 2% and control groups (p < 0.05). The anti-inflammatory and repairing effects of PBMT on an ischemic and delayed healing wound model in rats were shown by significant improvements in wound strength, stereological parameters, and gene expressions of bFGF, VEGF-A, and SDF-1α.

Light-induced nitric oxide release in the skin beyond UVA and blue light: Red & near-infrared wavelengths

Nitric oxide (NO) is omnipresent in the body and synthesized by 3 isoenzymes (nNOS, eNOS and iNOS), all detected in human skin. NO can be stored in a pool of compounds readily converted to NO following skin irradiation by UVR and blue light. This non-enzymatic (without NOS involvement) photolytic reaction mobilizes cutaneous stores of NO derivatives to the bloodstream, lowering blood pressure. However, with the likelihood of skin deleterious effects caused by UVR/blue light, safer wavelengths in the red/near-infrared (NIR) spectrum are becoming potential contenders to release cutaneous NO, possibly via NOS temperature-dependent effects. The use of red/NIR light to mobilize NO stores from the body's largest organ (the skin) is auspicious. This review focuses on UVR, blue, red, and NIR spectra and their capacity to release NO in human skin. PubMed and Google Scholar were used as article databases to find relevant publications related to this particular field.

Photobiomodulation therapy preconditioning modifies nitric oxide pathway and oxidative stress in human-induced pluripotent stem cell-derived ventricular cardiomyocytes treated with doxorubicin

Doxorubicin (DOX) is an anthracycline antibiotic that exhibits high heart toxicity. Human-induced pluripotent stem cell-derived ventricular cardiomyocytes (hiPSC-vCMs) are important in vitro models for testing drug cardiotoxicity. Photobiomodulation therapy (PBMT) is a non-invasive therapy that stimulates cells growth and self-repair using light irradiation. This study aimed to investigate the in vitro effects of PBMT preconditioning on cardiotoxicity induced by DOX. HiPSC-vCMs were treated with PBMT for 500 s, followed by the addition of 2 μM DOX. LED irradiation preconditioning parameters were at 660 nm with an irradiance of 10 mW/cm², performing 5 J/cm², followed by 24-h DOX exposure (2 μM). Human iPSC-vCMs treated with 2 μM DOX or irradiated with PBMT composed the second and third groups, respectively. The control group did neither receive PBMT preconditioning nor DOX and was irradiated with a white standard lamp. Cells from all groups were collected to perform mRNA and miRNA expressions quantification. PBMT, when applied before the DOX challenge, restored the viability of hiPSC-vCMs and reduced ROS levels. Although downregulated by DOX, myocardial UCP2 mRNA expression presented marked upregulation after PBMT preconditioning. Expression of eNOS and UCP2 mRNA and NO production were decreased after DOX exposure, and PBMT preconditioning before the DOX challenge reversed these changes. Moreover, our data indicated that PBMT preconditioning lowered the miR-24 expression. Our data suggested that PBMT preconditioning ameliorated in vitro DOX-induced cardiotoxicity on transcription level, restoring NO levels and reducing oxidative stress.

Photobiomodulation Response From 660 nm is Different and More Durable Than That From 980 nm

BACKGROUND AND OBJECTIVES

Photobiomodulation (PBM) therapy uses light at various wavelengths to stimulate wound healing, grow hair, relieve pain, and more-but there is no consensus about optimal wavelengths or dosimetry. PBM therapy works through putative, wavelength-dependent mechanisms including direct stimulation of mitochondrial respiration, and/or activation of transmembrane signaling channels by changes in water activity. A common wavelength used in the visible red spectrum is ~660 nm, whereas recently ~980 nm is being explored and both have been proposed to work via different mechanisms. We aimed to gain more insight into identifying treatment parameters and the putative mechanisms involved.

STUDY DESIGN/MATERIALS AND METHODS

Fluence-response curves were measured in cultured keratinocytes and fibroblasts exposed to 660 or 980 nm from LED sources. Metabolic activity was assessed using the MTT assay for reductases. ATP production, a major event triggered by PBM therapy, was assessed using a luminescence assay. To measure the role of mitochondria, we used an ELISA to measure COX-1 and SDH-A protein levels. The respective contributions of cytochrome c oxidase and ATP synthase to the PBM effects were gauged using specific inhibitors.

RESULTS

Keratinocytes and fibroblasts responded differently to exposures at 660 nm (red) and 980 nm (NIR). Although 980 nm required much lower fluence for cell stimulation, the resulting increase in ATP levels was short-term, whereas 660 nm stimulation elevated ATP levels for at least 24 hours. COX-1 protein levels were increased following 660 nm treatment but were unaffected by 980 nm. In fibroblasts, SDH-A levels were affected by both wavelengths, whereas in keratinocytes only 660 nm light impacted SDH-A levels. Inhibition of ATP synthase nearly completely abolished the effects of both wavelengths on ATP synthesis. Interestingly, inhibiting cytochrome c oxidase did not prevent the rise in ATP levels in response to PBM treatment.

CONCLUSION

To the best of our knowledge, this is the first demonstration of differing kinetics in response to PBM therapy at red versus NIR wavelength. We also found cell-type-specific differences in PBM therapy response to the two wavelengths studied. These findings confirm that different response pathways are involved after 660 and 980 nm exposures and suggest that 660 nm causes a more durable response. © 2021 Wiley Periodicals LLC.

Photobiomodulation induces microvesicle release in human keratinocytes: PI3 kinase-dependent pathway role

Microvesicles (MVs, 100-1000 nm diameter) are released into the extracellular environment by mammalian cells. MVs interact with near or remote cells through different mechanisms; in particular, MVs from human keratinocytes accelerate wound healing. Photobiomodulation by laser improves wound healing, but no information is available about its effects on MV release from human keratinocyte. Human-immortalized keratinocytes (human adult low-calcium high-temperature, HaCaT) were starved for 24 h and then irradiated using a 980-nm energy density of 0, 16.2, 32.5, and 48.7 J/cm². After 24 h, MVs released in the conditioned medium were isolated, stained, and quantified using flow cytometry. MVs were distinguished from exosomes on the basis of their volume (forward scatter signals). In some experiments, phosphatidylinositol 3-kinase (PI-3K) activity, involved in MV release and stimulated by laser light, was inhibited by pre-treating cells with Wortmannin (WRT, 10 μg/mL). MVs were observed in HaCaT-conditioned medium both in basal- and laser-stimulated conditions. Photobiomodulation therapy, also known as PBMT, was able to increase MV release from human keratinocytes reaching a maximum effect at 32.5 J/cm² with a stimulation of (148.6 ±15.1)% of basal (p<0.001). PI-3K activity inhibition strongly reduced both basal- and laser-induced MV release; but PBMT by laser still increased MV release, compared to basal values in the presence of WRT. In vitro near infrared photobiomodulation increased the releasing of MVs from human keratinocytes, while Wortmannin, a PI-3K inhibitor, negatively affects both basal- and laser-induced releasing. Laser-induced MV release could be a new effect of biostimulation on the wound healing process.

Low-Level Laser Therapy in Prevention of the Development of Endothelial Dysfunction and Clinical Experience of Treatment and Rehabilitation of COVID-19 Patients

OBJECTIVES

The aim of the article is to justify the application of low-level laser therapy (LLLT) to prevent the development of endothelial dysfunction in COVID-19 patients. The results of treating and rehabilitating patients with COVID-19 and prevention of the disease using low-level laser therapy (LLLT) are evaluated.

METHODS

A literature review is conducted on mechanisms of vascular homeostasis regulation, biomodulating effect of laser light, and LLLT methods for preventing endothelial dysfunction. A total of 106 patients were treated in two COVID-19 healthcare centers in Russia. 22 patients with SARS (+) pneumonia at the stage of resolving the pathological lesion were admitted to rehabilitation using pulsed IR laser. 14 patients with acute forms of COVID-19 were treated using LASMIK device: wavelength 904 nm, pulsed mode, externally and ILBI-525 (intravenous laser blood illumination) + LUVBI (ultraviolet laser blood illumination). 70 persons underwent preventive courses of noninvasive LLLT.

RESULTS

It was shown that LLLT is effective in preventing the development of endothelial dysfunction. Clinical experience demonstrated good tolerability of the treatment, improvement in sputum discharge, and an improvement in overall health. The severity of general hypoxia decreased by the 5th procedure. The procedures for prevention of the disease were well tolerated; there were no cases of COVID-19.

CONCLUSION

Low-level laser therapy is a justified treatment method that promotes lung tissue regeneration and mitigates the consequences of the disease. The obtained results confirm that LLLT can be used for the effective prevention and treatment of COVID-19 patients.

Effect of light emitting diode photobiomodulation on murine macrophage function after Bothrops envenomation

Several reports have suggested that photobiomodulation, owing to its analgesic, anti-inflammatory, and healing effects, may be an effective therapeutic option for local effects of snakebites when the availability and accessibility of conventional serum therapy are inefficient and far from medical care centers. Although there have been studies that demonstrate the application of photobiomodulation in the treatment of local adverse events due to snakebites from snakes of the genus Bothrops, its role in the activation of leukocytes, particularly macrophages, has not been evaluated. Here, we assessed the effect of light-emitting diode (LED) treatment on macrophage activation induced by B. jararacussu venom (BjV). LED treatment caused an increase in the viability of macrophages incubated with BjV. This treatment reduced reactive oxygen species (ROS) and nitric oxide (NO) production by macrophages after incubation with BjV. However, LED treatment did not interfere with IL-1β and IL-10 production by macrophages after incubation with BjV. In conclusion, this study showed that LED treatment has the potential to be used in combination with conventional serum therapy to prevent or minimize the progression of local to severe symptoms after Bothrops envenomation.

Photobiomodulation preserves mitochondrial redox state and is retinoprotective in a rodent model of retinitis pigmentosa

Photobiomodulation (PBM) by far-red (FR) to near-infrared (NIR) light has been demonstrated to restore the function of damaged mitochondria, increase the production of cytoprotective factors and prevent cell death. Our laboratory has shown that FR PBM improves functional and structural outcomes in animal models of retinal injury and retinal degenerative disease. The current study tested the hypothesis that a brief course of NIR (830 nm) PBM would preserve mitochondrial metabolic state and attenuate photoreceptor loss in a model of retinitis pigmentosa, the P23H transgenic rat. P23H rat pups were treated with 830 nm light (180 s; 25 mW/cm2; 4.5 J/cm2) using a light-emitting diode array (Quantum Devices, Barneveld, WI) from postnatal day (p) 10 to p25. Sham-treated rats were restrained, but not treated with 830 nm light. Retinal metabolic state, function and morphology were assessed at p30 by measurement of mitochondrial redox (NADH/FAD) state by 3D optical cryo-imaging, electroretinography (ERG), spectral-domain optical coherence tomography (SD-OCT), and histomorphometry. PBM preserved retinal metabolic state, retinal function, and retinal morphology in PBM-treated animals compared to the sham-treated group. PBM protected against the disruption of the oxidation state of the mitochondrial respiratory chain observed in sham-treated animals. Scotopic ERG responses over a range of flash intensities were significantly greater in PBM-treated rats compared to sham controls. SD-OCT studies and histological assessment showed that PBM preserved the structural integrity of the retina. These findings demonstrate for the first time a direct effect of NIR PBM on retinal mitochondrial redox status in a well-established model of retinal disease. They show that chronic proteotoxic stress disrupts retinal bioenergetics resulting in mitochondrial dysfunction, and retinal degeneration and that therapies normalizing mitochondrial metabolism have considerable potential for the treatment of retinal degenerative disease.

Proposed mechanisms of low-level light therapy in the treatment of androgenetic alopecia

Androgenetic alopecia (AGA) is a global challenge, affecting a large number of people worldwide. Efficacy of the existed treatments can barely meet the demands of patients. Patients who are poorly responding to those treatments are seeking for a more effective and suitable technique to treat their disease. Low-level light therapy (LLLT) is a newly developed technique, which has been proved to stimulate hair growth. Based on the function principle of LLLT in other domains and refer to the published literatures, we write this review to neaten and elucidate the possible mechanism of LLLT in the treatment of AGA. A review of published literature which is associated with keywords LLLT, photobiomodulation, AGA, treatment, hair growth, and mechanism was performed to elucidate the proposed mechanism of LLLT in the treatment of AGA. The present study shows that LLLT can accelerate hair growth in AGA patients. The proposed mechanism of LLLT in treating AGA may vary among different specialists. But we can summarize the consensual mechanisms as follows; low-level light absorbed by chromophores can lead to the production of nitric oxide (NO) and the modulation of reactive oxygen species (ROS). These mobilized molecules subsequently activate redox-related signaling pathways in hair follicle cells and perifollicular cells. Finally, these activated cells participate in the regrowth of hair follicle. Even though the efficacy of LLLT in the treatment of AGA in both men and women has already been confirmed, the present studies focusing on discovering LLLT are still inadequate and unsystematic. More studies are needed to standardize the optimum treatment parameters applied in promoting hair growth and determine the long-term safety and efficacy of LLLT. Current recognitions about the mechanisms of LLLT, mainly focused on the molecules that may take effect, neglected different cellular components that are functional in the hair follicle macro-environment.

Evaluation of low-level diode laser irradiation and various irrigant solutions on the biological response of stem cells from exfoliated deciduous teeth

This study aimed to evaluate cytotoxic effects and the apoptosis of Gallium-Aluminum-Arsenide (GaAlAs) diode laser irradiation, sodium hypochlorite (NaOCl), ozonated water and ethylene diamine tetraacetic acid (EDTA) on stem cells from human exfoliated deciduous teeth (SHEDs). Cells were exposed to EDTA (5%, 8.5%, 17%), NaOCl (1%, 2.5%, 5%) ozonated water (5, 10, 20 μg/ml) and GaAlAs diode laser irradiation (energy densities of 0.5, 1, 1.5 j/cm²). Culture medium included D-MEM, supplemented with 15% foetal bovine serum, 1% l-glutamine, 1% penicillin-streptomycin, 1% gentamycin, amphotericin-B and served as control group. The prepared irrigants were added to the relevant wells and incubated with the cells at 37 °C for 5, 10 and 15 min. The cells in the laser group were also incubated at 37 °C for 5, 10 and 15 min after the laser application. Cell viability and proliferation were analysed with the 3-[4,5-dimethylthiazol-2-yl]-2,5 diphenyl tetrazolium bromide (MTT) assay. The percentage of cell viability showed a significant reduction in all concentrations of the EDTA and NaOCl groups when compared to the control group, diode laser irradiation and ozonated water groups at 5th, 10th and 15th minutes respectively but high cytotoxic effects of all EDTA and NaOCl groups with decreased over 50% of cell viability were observed at the 15th minute. Also EDTA group with 17% concentration (17%E) presented the lowest survival rate on SHEDs with mean of 21.67% ± 6.101 at this time interval. The lowest toxic effects were observed at the 5th minutes compared to other time periods at experimental groups. For detection of apoptotic cells, the terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate nick end labelling (TUNEL) method was performed. According to the MTT results, doses showed the highest toxicity (cell survival decreased over 50%) in each group were selected for TUNEL assay (17% EDTA; 1% NaOCl; 10 μg/ml Ozonated water; 1.5 j/cm² diode laser irradiation). The significantly lowest percentages of TUNEL-positive cells were detected in ozonated water (10.67% ± 2.93) and diode laser irradiation (13.24% ± 7.61) compared to EDTA (39.89% ± 11.54) and NaOCl (31.15% ± 10.64) respectively. Also the difference between percentage of TUNEL-positive cells in EDTA and NaOCl groups was not significant. Synergistic combination of ozonated water and diode laser irradiation may be used in the disinfection step of necrotic root canals.

Photobiomodulation therapy promotes in vitro wound healing in nicastrin KO HaCaT cells

Mutations in NCSTN gene (encoding for nicastrin protein) are associated with hidradenitis suppurativa (HS), a chronic inflammatory disease involving hair follicles. HS is clinically handled with drugs but the most severe cases are treated with surgery. Photobiomodulation (PBM) therapy, already used in the treatment of skin diseases such as acne, herpes virus lesions, ultraviolet damage, vitiligo, hypertrophic scar, keloid, burn, psoriasis and diabetic chronic wounds, could be beneficial as an adjuvant supportive treatment to promote and foster the healing process after skin excision in HS. The effects of PBM therapy in promoting the wound closure are evaluated in a HaCaT cells NCSTN-/-, assessing cell metabolism, migration rate, proliferation and cell cycle progression. In our experimental model, PBM exerts a potent action on metabolism of mutated keratinocytes, incrementing adenosine triphosphate (ATP) production at 2 hours, while after 24 hours an increase of metabolism with a decrement of intracellular ATP levels were recorded. Moreover, PBM speeds up the wound closure, inducing cells' migration without affecting their proliferation.Based on our findings, we suggest the use of PBM in HS patients, who undergo major surgery with large skin excision.

Nitric oxide regulates intussusceptive-like angiogenesis in wound repair in chicken embryo and transgenic zebrafish models

Angiogenesis is the formation of new blood vessels that occurs by two distinct processes following sprouting angiogenesis (SA) and intussusceptive angiogenesis (IA). Nitric oxide (NO) is known for its pro-angiogenic functions. However, no clear mechanisms are delineated on its role in promoting angiogenesis in reparative wound healing. We propose that NO regulates SA to IA transition and vice versa in wound milieu. We have used three models which include a new chick embryo extra-vasculature (CEV) burn wound model, adult Tie2-GFP transgenic Zebrafish caudal fin regeneration model and Zebrafish skin wound model to study the mechanisms underlying behind the role of NO in wound healing. Wounds created in CEV were treated with NO donor (Spermine NONOate (SPNO)), NOS inhibitor (L-nitro-l-arginine-methyl ester (l-NAME)), NaNO₂, NaNO₃, and beetroot juice, a nitrite-rich juice respectively and the pattern of wound healing was assessed. Morphological and histological techniques tracked the wound healing at the cellular level, and the molecular changes were investigated by using real-time RT-PCR gene expression analysis. The result concludes that NO donor promotes wound healing by activating SA at an early phase of healing while NOS inhibitor induces wound healing via IA. At the later phase of wound healing NO donor followed IA while NOS inhibitor failed to promote wound repair. The current work underpinned a differential regulation of NO on angiogenesis in wound milieu and this study would provide new insights in designing therapeutics for promoting wound repair.