The Effects of Photobiomodulation on Inflammatory Infiltrate During Muscle Repair in Advanced-Age Rats.

Photobiomodulation (PBM) enhances muscle repair in aged animals, but its effect on the modulation of the phenotype of immune cells has not yet been determined. Rats (20-month-old) were submitted to cryoinjury of the tibialis anterior muscle and were treated with PBM. After 1, 3, and 7 days, the muscles were submitted to immunohistochemical analysis for the determination of neutrophils and macrophage phenotypes. The muscles treated with PBM exhibited a smaller number of neutrophils after 1 day of treatment and a greater number of both M1 and M2 macrophages after 3 days of treatment. The irradiated tissues exhibited a smaller amount of both macrophage phenotypes after 7 days of treatment. PBM produced temporal alterations in the phenotype of the inflammatory cells during muscle repair process in advanced-age animals, indicating that these mechanisms may contribute to the beneficial effects of this therapy in the treatment of muscle injuries.

Comparative effects of low-level laser therapy pre- and post-injury on mRNA expression of MyoD, myogenin, and IL-6 during the skeletal muscle repair.

This study analyzed the effect of pre-injury and post-injury irradiation with low-level laser therapy (LLLT) on the mRNA expression of myogenic regulatory factors and interleukin 6 (IL-6) during the skeletal muscle repair. Male rats were divided into six groups: control group, sham group, LLLT group, injury group; pre-injury LLLT group, and post-injury LLLT group. LLLT was performed with a diode laser (wavelength 780 nm; output power 40 mW' and total energy 3.2 J). Cryoinjury was induced by two applications of a metal probe cooled in liquid nitrogen directly onto the belly of the tibialis anterior (TA) muscle. After euthanasia, the TA muscle was removed for the isolation of total RNA and analysis of MyoD, myogenin, and IL-6 using real-time quantitative PCR. Significant increases were found in the expression of MyoD mRNA at 3 and 7 days as well as the expression of myogenin mRNA at 14 days in the post-injury LLLT group in comparison to injury group. A significant reduction was found in the expression of IL-6 mRNA at 3 and 7 days in the pre-injury LLLT and post-injury LLLT groups. A significant increase in IL-6 mRNA was found at 14 days in the post-injury LLLT group in comparison to the injury group. LLLT administered following muscle injury modulates the mRNA expression of MyoD and myogenin. Moreover, the both forms of LLLT administration were able to modulate the mRNA expression of IL-6 during the muscle repair process.

Photobiomodulation with 660-nm and 780-nm laser on activated J774 macrophage-like cells: Effect on M1 inflammatory markers.

M1 profile macrophages exert a major influence on initial tissue repair process. Few days after the occurrence of injury, macrophages in the injured region exhibit a M2 profile, attenuate the effects of the M1 population, and stimulate the reconstruction of the damaged tissue. The different effects of macrophages in the healing process suggest that these cells could be the target of therapeutic interventions. Photobiomodulation has been used to accelerate tissue repair, but little is known regarding its effect on macrophages. In the present study, J774 macrophages were activated to simulate the M1 profile and irradiated with two different sets of laser parameters (780 nm, 70 mW, 2.6J/cm(2), 1.5s and 660 nm, 15 mW, 7.5 J/cm(2), 20s). IL-6, TNF-α, iNOS and COX-2 gene and protein expression were analyzed by RT-qPCR and ELISA. Both lasers were able to reduce TNF-α and iNOS expression, and TNF-α and COX-2 production, although the parameters used for 780 nm laser provided an additional decrease. 660 nm laser parameters resulted in an up-regulation of IL-6 expression and production. These findings imply a distinct, time-dependent modulation by the two different sets of laser parameters, suggesting that the best modulation may involve more than one combination of parameters.

Effect of photobiomodulation on expression of IL-1ß in skeletal muscle following acute injury.

Muscle repair is regulated by growth factors and cytokines. Low-level laser therapy (LLLT) seems to influence acute inflammation and accelerate skeletal muscle repair. This study verifies the effect of LLLT on the expression of IL-1ß in the tibialis anterior (TA) muscle of rats following acute injury. Wistar rats (n=35) were allocated into three groups: control (without lesion and LLLT, n=5), injury group (n=15), and injury + LLLT group (n=15). The acute injury was induced by the contact with a cooled metal probe (3 mm in diameter) during 10 s, twice, in the same muscle area. LLLT was used three times a week using the InGaAlP laser (660 nm; beam spot of 0.04 cm(2), output power of 20 mW, power density of 500 mW/cm(2), and energy density of 5 J/cm(2) during 10 s). The animals were analyzed at 1, 7, and 14 days following injury. TA muscles samples were used for obtaining total RNA and performing cDNA synthesis. Real-time polymerase chain reactions were realized using IL-1ß primer. There was a decrease in IL-1ß expression after 7 days in LLLT group in comparison with the no treated group. In conclusion, LLLT was able to decrease IL-1ß expression during the skeletal muscle repair following an acute injury.

Effect of low-level laser therapy on proliferation, differentiation, and adhesion of steroid-treated osteoblasts.

There has recently been constant effort to evaluate therapies that may have a positive effect on bone regeneration. However, there are few studies in the literature on the effects of low-level laser therapy (LLLT) involving tissues treated with anabolic steroids. The present study evaluated the effects of LLLT (AsGaAl 780 nm, 3 J/cm(2), 10 mW, beam spot of 0.04 cm(2), total energy 0.12 J) on the proliferation, adhesion, and differentiation of osteoblasts cultured in the presence of nandrolone decanoate (ND). The MTT method was employed to evaluate cell proliferation and adhesion. Cell differentiation was evaluated by measuring alkaline phosphatase activity. There was a significant decrease in cell proliferation in the irradiated group treated with 50 µM ND when compared to the control group, after 48 h. After 72 h, cell proliferation was significantly greater in the control group than in the irradiated groups treated with the steroid at concentrations of 10, 25, and 50 µM. With regard to cell differentiation, alkaline phosphatase activity was significantly higher in the irradiated group treated with 50 µM ND than in the control group, irradiated non-treated group, and irradiated group treated with 25 µM ND. After 60 min of plating, the irradiated non-treated group and irradiated groups treated with the steroid at concentrations of 5, 10, and 25 µM exhibited a significant increase in cell adhesion compared to the control group. LLLT in combination with a high concentration of steroid inhibited cell proliferation, possibly by inducing cell differentiation, while irradiation combined with lower concentrations of the steroid induced an increase in cell adhesion.

Efeito da laserterapia de baixa potênciasobre a proliferação de mioblastos C2C12 / Effect of low-energy laser irradiation on the proliferation of C2C12 myoblasts

Os efeitos da laserterapia de baixa potência estão diretamenterelacionados aos parâmetros dosimétricos e ao tipo de laser utilizado.O objetivo do presente estudo foi avaliar o efeito de diferentes dosesde irradiação dos lasers de GaAlAs e de InGaAlP sobre a proliferaçãode mioblastos cultivados em situação de carência nutricional (modelode mimetização de injúria muscular). Os mioblastos C2C12cultivados em meio defi ciente em nutrientes foram irradiados comlaser de baixa potência de GaAlAs (660 nm) e InGaAlP (780 nm)com densidades de energia de 1,3, 2,5, 3,8 e 5 J/cm2 e 1,3, 2,5, 5e 6,3 J/cm2, respectivamente. A proliferação celular foi avaliada48 horas após a irradiação por meio da mensuração da atividademitocondrial e do ensaio de cristal violeta. Não houve diferençasignifi cativa na proliferação celular entre as culturas irradiadas eculturas de controle para qualquer um dos parâmetros. Mais estudossão necessários para determinar os parâmetros ideais da laserterapiana bioestimulação de mioblastos...

The effects of phototherapy using low-level laser depend onirradiation parameters and the type of laser used. Th e aim of thepresent study was to evaluate the eff ect of phototherapy on theproliferation of C2C12 myoblasts in cell culture under defi cientnutritional condition (muscle injury model) using low-level GaAlAsand InGaAlP lasers. C2C12 myoblasts in nutrient-defi cient mediumwere irradiated with low-level GaAlAs (660 nm) and InGaAlP (780nm) lasers with energy densities of 1.3, 2.5, 3.8 e 5 J/cm2, and 1.3,2.5, 5 e 6.3 J/cm2, respectively. Cell proliferation was assessed 48hours after irradiation by measuring the mitochondrial activity andby the crystal violet assay. Th ere were no signifi cant diff erences in cellproliferation between laser-treated myoblasts and control culturesfor any of the parameters. Further studies are necessary to determinethe correct laser parameters for the biostimulation of myoblasts...