Effect of Photobiomodulation in Lipopolysaccharide-Treated Myoblasts.

Objective: To evaluate the effect of photobiomodulation (PBM) on cell viability, synthesis of nitric oxide (NO), and interleukin (IL)-6 inflammatory cytokine production in myoblasts cultured in the presence of lipopolysaccharides (LPSs). Methods: C2C12 myoblasts were treated with LPS and PBM using different parameters (wavelength: 780 nm; beam spot: 0.04 cm2; power output: 10 or 40 mW; energy density: 5 or 20 J/cm2; and 20-sec exposure time). Nonirradiated cells were used to the control group. Results: An increase in cell viability was found in both LPS groups in comparison with the control. PBM with the higher power output (40 mW) induced a reduction in cell viability. PBM also modulated the synthesis of NO in the myoblasts, but did not alter the expression of IL-6. Conclusions: Based on these findings, PBM is capable of modulating the cell viability and the production of NO in LPS-treated myoblasts and it is, therefore, a possible tool for the treatment of muscle injury caused by infection.

Indoxyl Sulfate Contributes to Uremic Sarcopenia by Inducing Apoptosis in Myoblasts.

OBJETIVE: Uremic sarcopenia is a complication of chronic kidney disease, particularly in its later stages, which leads to musculoskeletal disability. Uremic toxins have been linked to the pathogenesis of several manifestations of uremic syndrome. We sought to investigate whether indoxyl sulphate (IS), a protein-bound uremic toxin, is implicated in the development of uremic sarcopenia. MATERIAL AND METHODS: Myoblasts were exposed to IS at normal (0.6 mg/L, IS0.6), uremic (53 mg/L, IS53) or maximum uremic (236 mg/L, IS236) concentrations for 24, 48 and 72 h. Cell viability was evaluated by MTT assay and by 7-aminoactinomycin D staining. ROS generation and apoptosis were evaluated by flow cytometry. MyoD and myogenin mRNA expression was evaluated by qRT-PCR and myosin heavy chain expression by immunocytochemistry. RESULTS: Myoblast viability was reduced by IS236 in a time-dependent pattern (p <0.05; 84.4, 68.0, and 63.6%). ROS production was significantly higher (p <0.05) in cells exposed to IS53 and IS236 compared to control (untreated cells). The apoptosis rate was significantly higher in cells treated with IS53 and IS236 than in control after 48h (p <0.05; 4.7 ± 0.1% and 4.6 ± 0.3% vs. 3.1 ± 0.1%, respectively) and 72h (p <0.05; 9.6 ± 1.1% and 10.4 ± 0.3% vs. 3.1 ± 0.7%, respectively). No effect was observed on MyoD, myogenin, myosin heavy chain expression, and markers of myoblast differentiation at any IS concentration tested or time-point experiment. CONCLUSIONS: These data indicate that IS has direct toxic effects on myoblast by decreasing its viability and increasing cell apoptosis. IS may be a potential target for treating uremic sarcopenia.

Ultrassom terapêutico na atividade mitocondrial e diferenciação de células musculares C2C12 / Therapeutic ultrasound in the mitochondrial activity and differentiation of muscle cells C2C12

Introdução: O ultrassom terapêutico (US) é muito utilizado na prática clínica, mas há poucos estudos sobre seu efeito na regeneração muscular. Objetivo: Avaliar os efeitos do US sobre a atividade mitocondrial e diferenciação de células musculares C2C12, quando aplicado concomitantemente à indução do processo de diferenciação. Métodos: As células musculares foram submetidas ao processo de diferenciação pela adição de meio de cultura DMEM, suplementado com 2% de soro de cavalo, e receberam simultaneamente tratamento com US (pulsado a 20%, 3 MHz, 0,2 e 0,5 W/cm², 5 minutos). A atividade mitocondrial foi avaliada após 24h, 48h e 96h pelo método MTT, e a diferenciação celular após um e três dias pela atividade de creatina quinase (CK). Resultados: Não houve alteração da atividade mitocondrial e de CK nos grupos que receberam tratamento com US nos diferentes períodos avaliados. Conclusão: O US, nos parâmetros avaliados, não foi capaz de alterar a atividade mitocondrial e a diferenciação de células musculares C2C12.

Introduction: The therapeutic ultrasound (US) has been widely used in clinical practice, but there are few studies on its effect on muscle regeneration. Objective: To evaluate the effects of the US on mitochondrial activity and differentiation of muscle cells C2C12 when applied concomitantly the induction of the differentiation process. Methods: Muscle cells were subjected to differentiation process by addition of DMEM culture medium supplemented with 2% horse serum and received concomitant treatment with US (pulsed at 20%, 3 MHz, 0.2 and 0.5 W/cm², 5 minutes). The mitochondrial activity was assessed after 24, 48 and 96 hours by MTT assay and cell differentiation after one and three days for the activity of creatine kinase (CK). Results: There was no change in mitochondrial activity and CK in the groups receiving US treatment in different periods. Conclusion: In the evaluated parameters, the US was not able to change mitochondrial activity and differentiation of muscle cells C2C12.