Preventive and therapeutic vascular photobiomodulation decreases the inflammatory markers and enhances the muscle repair process in an animal model.

Photobiomodulation therapy (PBM) has shown positive effects when applied locally to modulate the inflammatory process and facilitate muscle repair. However, the available literature on the mechanisms of action of vascular photobiomodulation (VPBM), a non-invasive method of vascular irradiation, specifically in the context of local muscle repair, is limited. Thus, this study aimed to assess the impact of vascular photobiomodulation (VPBM) using a low-level laser (LLL) on the inflammatory response and the process of skeletal muscle repair whether administered prior to or following cryoinjury-induced acute muscle damage in the tibialis anterior (TA) muscles. Wistar rats (n = 85) were organized into the following experimental groups: (1) Control (n = 5); (2) Non-Injury + VPBM (n = 20); (3) Injured (n = 20); (4) Pre-VPBM + Injury (n = 20); (5) Injury + Post-VPBM (n = 20). VPBM was administered over the vein/artery at the base of the animals' tails (wavelength: 780 nm; power: 40 mW; application area: 0.04 cm2; energy density: 80 J/cm2). Euthanasia of the animals was carried out at 1, 2, 5, and 7 days after inducing the injuries. Tibialis anterior (TA) muscles were collected for both qualitative and quantitative histological analysis using H&E staining and for assessing protein expression of TNF-α, MCP-1, IL-1ß, and IL-6 via ELISA. Blood samples were collected and analyzed using an automatic hematological analyzer and a leukocyte differential counter. Data were subjected to statistical analysis (ANOVA/Tukey). The results revealed that applying VPBM prior to injury led to an increase in circulating neutrophils (granulocytes) after 1 day and a subsequent increase in monocytes after 2 and 5 days, compared to the Non-Injury + VPBM and Injured groups. Notably, an increase in erythrocytes and hemoglobin concentration was observed in the Non-Injury + VPBM group on days 1 and 2 in comparison to the Injured group. In terms of histological aspects, only the Prior VPBM + Injured group exhibited a reduction in the number of inflammatory cells after 1, 5, and 7 days, along with an increase in blood vessels at 5 days. Both the Prior VPBM + Injured and Injured + VPBM after groups displayed a decrease in myonecrosis at 1, 2, and 7 days, an increase in newly-formed and immature fibers after 5 and 7 days, and neovascularization after 1, 2, and 7 days. Regarding protein expression, there was an increase in MCP-1 after 1 and 5 days, TNF-α, IL-6, and IL-1ß after 1, 2, and 5 days in the Injured + VPBM after group when compared to the other experimental groups. The Prior VPBM + Injured group exhibited increased MCP-1 production after 2 days, in comparison to the Non-Injury + VPBM and Control groups. Notably, on day 7, the Injured group continued to show elevated MCP-1 protein expression when compared to the VPBM groups. In conclusion, VPBM effectively modulated hematological parameters, circulating leukocytes, the protein expression of the chemokine MCP-1, and the proinflammatory cytokines TNF-α and IL-1ß, ultimately influencing the inflammatory process. This modulation resulted in a reduction of myonecrosis, restoration of tissue architecture, increased formation of newly and immature muscle fibers, and enhanced neovascularization, with more pronounced effects when VPBM was applied prior to the muscle injury.

Effect of Photobiomodulation Combined with Physiotherapy on Functional Performance in Children with Myelomeningo-Cele-Randomized, Blind, Clinical Trial.

BACKGROUND: This study aimed to evaluate the electrical activity of the rectus femoris, tibialis anterior, and lateral gastrocnemius muscles during the sit-to-stand task and functional mobility after a neurofunctional physiotherapy protocol associated with PBM. METHODS: Twenty-five children were randomly allocated to either Active PBM + physiotherapy (n = 13) or PBM sham + physiotherapy (n = 12). PBM was carried out with a LED device (850 nm, 25 J, 50 s per point and 200 mW) at four points over the area with absence of a spiny process. Both groups completed a twelve-week supervised program with two weekly 45-60 min sessions. Pre-training and post-training assessments involved the Pediatric Evaluation of Disability Inventory (PEDI). Muscle activity was assessed using portable electromyography (BTS Engineering) and the electrodes were positioned on the lateral gastrocnemius, anterior tibialis, and rectus femoris muscles. The RMS data were recorded and analyzed. RESULTS: After 24 sessions of the treatment protocol, improvements were found in the PEDI score. The participants presented greater independence in performing the tasks, requiring less assistance from their caregivers. More significant electrical activity was found in the three muscles evaluated between the rest period and execution of the sit-to-stand tasks, both in the more compromised or less compromised lower limbs. CONCLUSION: Neurofunctional physiotherapy with or without PBM improved functional mobility and electrical muscle activity in children with myelomeningocele.

Effects of systemic vascular photobiomodulation using LED or laser on sensory-motor recovery following a peripheral nerve injury in Wistar rats.

Peripheral nerve injury (PNI) is associated with considerable functional impairment. Photobiomodulation (PBM) has demonstrated positive effects regarding neuromuscular repair after PNI when applied locally to the nerve or injured muscle. However, the effects of systemic PBM with transcutaneous application over an important artery, which is also denominated vascular PBM (VPBM), remain unclear. The aim of the study was to compare the effects of VPBM with low-level laser (LLL) and light-emitting diode (LED) on gait, sensitivity and muscle morphology following a PNI. PNI was induced on Wistar rats using the sciatic nerve crushing technique. VPBM was performed over the rat's artery tail region with LED (850 nm, 40 mW, 3.2 J) and LLL (780 nm, 40 mW, 3.2 J). Gait functionality, mechanical (nociceptive) sensitivity, and morphology of the tibialis anterior muscle were evaluated at 7, 14, and 21 days after injury. An improvement in functional gait was shown in the VPBM-LLL group in all periods. Motor sensitivity was found after 14 days in the VPBM-LLL group. The left/right (L/R) muscle mass ratio revealed a reduction in muscle atrophy in the VPBM-LLL group at 7 days. Muscle fiber diameter increased in the VPBM-LED group at 14 days and increases in the cross-section area were found in the VPBM-LED and VPBM-LLL groups at 7 days. VPBM with both light sources (LED and LLL) positively modulated functioning and neuromuscular recovery following sciatic nerve injury in rats, with more pronounced results when using LLL.

Simultaneous red and infrared light-emitting diodes reduced pain in individuals with temporomandibular disorder: a randomized, controlled, double-blind, clinical trial.

The aim of the present study was to evaluate the effects of photobiomodulation (PBM) with the simultaneous use of red and infrared LEDs on pain and mandibular range of motion in individuals with temporomandibular disorder (TMD). Eighteen participants were randomly allocated to an LED group or control group. The device had 18 red LEDs (660 nm) and 18 infrared LEDs (850 nm), with a total power irradiated of 126 mW and 75.6 J per point. The device was placed in the regions of the temporomandibular joint (TMJ) and masticatory muscles once per day three times per week for 2 weeks. Pain intensity was measured using the visual analog scale (VAS). Mandibular range of motion was determined using digital calipers and considering different conditions (unassisted opening without pain, maximum opening with and without assistance, right and left lateral movements, and protrusion). Evaluations were performed before treatment, immediately after the first LED irradiation session and at the end of six sessions. A significant reduction in pain intensity was found in the LED group at the end of treatment compared to the control group (p < 0.001) as well as in the comparison between the pretreatment and end of treatment evaluations (p < 0.001). Regarding mandibular movements, no statistically significant differences between the LED group and control group were found at the end of treatment for any of the conditions analyzed or in the comparison between the beginning and end of treatment with LED. Photobiomodulation using a cluster with red and infrared LEDs induced a reduction in pain in individuals with temporomandibular disorder but did not alter mandibular range of motion in these individuals. Trial registration number: NCT03696706; retrospectively registered (ClinicalTrials.gov).

Fotobiomodulação com LED induz melhora na funcionalidade da marcha em ratos após lesão nervosa periférica / Photobiomodulation with LED increased the gait functionality in rats submitted to peripheral nerve injury

Introdução: As lesões nervosas periféricas (LNP) podem resultar em distúrbios motores e sensoriais alterando a funcionalidade do membro afetado, porém pouco se conhece a respeito dos efeitos da fotobiomodulação (FBM) com diodo emissor de luz (LED). Objetivo: Analisar os efeitos do LED sobre a funcionalidade da marcha de ratos Wistar pós LNP. Metodologia: Ratos Wistar foram submetidos a LNP por esmagamento de ciático e analisados nos seguintes grupos experimentais: (1) Controle; (2) LNP; (3) LNP+ LED (780 nm, potência média 40 mW, exposição radiante, energia por ponto, 3,2 J sobre o nervo ciático (LEDn); (4) LNP+ LED em nervo e região do músculo envolvido (LEDnm) e (5) LNP+ LED apenas em região do músculo (LEDm). Após 7, 14, 21 e 28 dias foram realizadas as análises de marcha utilizando o Índice Funcional Ciático (IFC). Resultado: Após 7 dias, os grupos tratados com LED apresentaram uma melhora da marcha em relação ao grupo Lesão, sendo essa melhora mais pronunciada no grupo LEDn. Após 14 dias, os grupos LEDn e LEDnm apresentaram valores semelhantes ao grupo controle e após 21 e 28 dias o IFC não apresentou diferenças entre os grupos experimentais. Conclusão: O LED aumentou a funcionalidade da marcha avaliada pelo IFC após 1 e 2 semanas pós LNP, especialmente quando foi usado na região nervosa associada ou não à região muscular.

Introduction: Peripheral nerve injuries (PNI) can result in motor and sensory disturbances altering the functionality of the affected limb, however not much is known about the effects of photobiomodulation (PBM) with light emitting diode (LED). Objective: We aimed to analyze the effects of LED on the gait function of Wistar rats after PNI. Methodology: Wistar rats were submitted to PNI by sciatic crush and analyzed in the following experimental groups: (1) Control; (2) PNI; (3) PNI+ LED (780 nm, mean power 40 mW, radiant exposure, energy per spot, 3.2 J on the sciatic nerve) (LEDn); (4) LNP+ LED on nerve and involved muscle region (LEDnm) and (5) LNP+ LED only on muscle region (LEDm). After 7-, 14-, 21- and 28-days gait analyses were performed using the Sciatic Functional Index (SFI). Results: After 7 days, the groups treated with LED showed an improvement in gait compared to the PNI group, with this improvement being more pronounced in the LEDn group. After 14 days, the LEDn and LEDnm groups showed similar values to the control group and after 21 and 28 days the SFI did not show differences between the experimental groups. Conclusion: LED increased the gait functionality evaluated by SFI after 1 and 2 weeks post-PNI, especially when it was used in the nerve region associated or not with the muscle region.

Effects of photobiomodulation in experimental spinal cord injury models: A systematic review.

This systematic review investigated the repercussions of photobiomodulation using low-level laser therapy (LLLT) for the treatment of spinal cord injury (SCI) in experimental models. Studies were identified from relevant databases published between January 2009 and December 2021. Nineteen original articles were selected and 68.4% used light at an infrared wavelength. There was a considerable variation of the power used (from 25 to 200 mW), total application time (8-3000 s) and total energy (0.3-450 J). In 79% of the studies, irradiation was initiated immediately after or within 2 h of the SCI, and treatment time ranged continuously from 5 to 21 days. In conclusion, LLLT can be an auxiliary therapy in the treatment of SCI, playing a neuroprotective role, enabling functional recovery, increasing the concentration of nerve connections around the injury site and reducing pro-inflammatory cytokines. However, there is a need for standardization in the dosimetric parameters.

Histological and biochemical effects of preventive and therapeutic vascular photobiomodulation on rat muscle injury.

The intravascular or transcutaneous application of photobiomodulation (PBM) over blood vessels (vascular photobiomodulation, VPBM) has been used for the treatment of inflammatory and chronic conditions with promising systemic results. This study evaluated the VPBM effects on a model of muscle regeneration after acute injury and compared the outcomes of preventive and therapeutic VPBM. Transcutaneous VPBM was administered over the rat's main tail vein. Serum levels of creatine kinase (CK), aspartate aminotransferase (AST), and lactate were evaluated and muscles were processed for macroscopic and microscopic analysis. Preventive and therapeutic VPBM led to decreased inflammatory infiltrate, edema, and myonecrosis but with an increase in immature muscle fibers. CK, AST, and lactate levels were lower in the groups treated with VPBM (lowest concentrations in preventive VPBM application). Preventive and therapeutic VPBM were capable of exerting a positive effect on acute muscle injury repair, with more accentuated results when preventive VPBM was administered.