Phototherapy with low-level laser affects the remodeling of types I and III collagen in skeletal muscle repair

Abstract

The purpose of this article was to analyze the photobiomodulator role of low-level laser therapy (LLLT) on the skeletal muscle remodeling following cryoinjury in rats, focusing the types I and III collagen proteins. Laser phototherapy has been employed to stimulate repair in different tissues. However, its role in skeletal muscle remodeling is not yet well clarified, especially its effect on the collagen component of the extracellular matrix. Fifty adult Wistar rats were divided into four groups: control, sham, cryoinjury, and laser-treated cryoinjury. Laser irradiation was performed three times a week on the injured region using the InGaAlP (indium-gallium-aluminum-phosphorous) laser (660 nm; beam spot of 0.04 cm(2), output power of 20 mW, power density of 0.5 mW/cm(2), energy density of 5 J/cm(2), 10-s exposure time, with a total energy dose of 0.2 J). Five animals were killed after short-term (days 1 and 7) and long-term (14 and 21) durations following injury. The muscles were processed and submitted to hematoxylin and eosin (H&E) and immunohistochemical staining. The histological slices were analyzed qualitatively, semi-quantitatively, and quantitatively. The data were submitted to statistical analysis using the Kruskal-Wallis test. The qualitative analysis of morphological aspects revealed that the muscle repair were very similar in cryoinjury and laser groups on days 1, 14 and 21. However, at 7 days, differences could be observed because there was a reduction in myonecrosis associated to formation of new vessels (angiogenesis) in the laser-treated group. The analysis of the distribution of types I and III collagen, on day 7, revealed a significant increase in the depositing of these proteins in the laser-treated group when compared to the cryoinjury group. InGaAlP diode laser within the power parameters and conditions tested had a biostimulatory effect at the regenerative and fibrotic phases of the skeletal muscle repairs, by promoting angiogenesis, reducing myonecrosis, and inducing types I and III collagen synthesis, following cryoinjury in rat.

Photobiomodulation and different macrophages phenotypes during muscle tissue repair

“…Using PBM at 660 nm (20 mW and 1.6 J) with the same experimental model, De Souza et al12 and Mesquita‐Ferrari et al16 also found a reduction in myonecrosis at 7 days as well as a reduction in TNF‐ α mRNA expression after 1 and 7 days. TNF‐ α is a proinflammatory cytokine that stimulates myogenic cell proliferation, but also inhibits its differentiation and fusion 3, 24.…”

“…Cryoinjury, which can be considered an acute injury1, 12, 13, 16, 17, 21 provoked myonecrosis and the infiltration of inflammatory cells in the injured area on Day 2. A large number of CD68 + macrophages (M1) and small number of CD206 + and CD163 + (M2) macrophages were also found 2 days after injury, which is in accordance with previous descriptions (for review, see1).…”

“…The laser beam was applied in contact with the skin surface over the cryoinjury area at an angle of 90° between the emitter and skin to prevent reflection. Irradiation was applied to 8 points (Figure S2B) surrounding the sutured area 12, 16, 17, 18. After 2, 4 and 7 days of treatment, the animals were weighed and euthanized with an overdose of anesthesia (240 mg/kg of ketamine and 30 mg/kg of xylazine).…”

Fractal Analysis of Skeletal Muscle Tissue of Rats Subjected to Stretch Injury

“…Such alterations are visible when analyzed using histological slides in a light microscope (Alves et al, 2013;Camargo Filho et al, 2011;Luo et al, 2013;de Souza et al, 2011). However, currently these microscopic changes are evaluated qualitatively, which does not enable quantification of morphological changes.…”

Qualidade de vida em mulheres com fibromialgia submetidas à laserterapia de baixa intensidade

“…Diversos autores (SCHIMITT et al, 1993;SOUZA et al, 2011;TATARUNAS;MATERA;DAGLI, 1998;FULOP et al, 2010) comprovaram tais efeitos do laser, inclusive relacionados à angiogênese.…”