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. © 2018 Wiley Periodicals, Inc.