Effects of myogenic precursor cells (C2C12) transplantation and low-level laser therapy on muscle repair

Objective: The aim of the present study was to evaluate the effects of myoblast inoculation in combination with photobiomodulation therapy (PBMT) on skeletal muscle tissue following injury. Materials and Methods: Sixty-five Wistar rats were divided into five groups: Control—animals not submitted to any procedure; Injury—cryoinjury of the tibialis anterior muscle; HBSS—animals submitted to cryoinjury and intramuscular Hank's Balanced Salt Solution; Injury + Cells—animals submitted to cryoinjury, followed by myogenic precursor cells (C2C12) transplantation; Injury + Cells + LLLT—animals submitted to cryoinjury, followed by myogenic precursor cells (C2C12) transplantation and PBMT (780 nm, 40 mW, 3.2 J in 8 points). The periods analyzed were 1, 3, and 7 days. The tibialis anterior muscle was harvest for histological analysis, collagen analysis, and immunolabeling of macrophages. Results: No differences were found between the HBSS group and injury group. The Injury + Cells group exhibited an increase of inflammatory cells and immature fibers as well as a decrease in the number of macrophages on Day 1. The Injury + Cells + LLLT group exhibited a decrease in myonecrosis and inflammatory infiltrate at 7 days, but an increase in inflammatory infiltrate at 1 and 3 days as well as an increase in blood vessels at 3 and 7 days, an increase in macrophages at 3 days and better collagen organization at 7 days. Conclusion: Cell transplantation combined with PBMT led to an increase in the number of blood vessels, a reduction in myonecrosis and total inflammatory cells as well as better organization of collagen fibers during the skeletal muscle repair process. Lasers Surg. Med. 50:781–791, 2018.