Lasers in Surgery and Medicine Effects of Myogenic Precursor Cells (C2C12) Transplantation and Low-Level Laser Therapy on Muscle Repair Lucas Andreo, 1 Raquel A. Mesquita-Ferrari, PhD, 1,2Ã Beatriz G. Ribeiro, PhD, 2 Adriana Benitte, 3 Tatiane de F atima Nogueira, 3 Cristiane M. Franc ¸a, PhD, 1 Daniela de F atima Teixeira da Silva, PhD, 1 Sandra K. Bussadori, PhD, 1,2 Kristianne P.S. Fernandes, PhD, 1 Fernanda I. Corr^ ea, PhD, 2 and Jo~ ao C.F. Corr^ ea, PhD 2 1 Postgraduate Program in Biophotonics Applied to Health Sciences, Universidade Nove de Julho (UNINOVE), S ~ ao Paulo, SP, Brazil 2 Postgraduate Program in Rehabilitation Sciences, UNINOVE, S ~ ao Paulo, SP, Brazil 3 UNINOVE, S ~ ao Paulo, SP, Brazil 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 þ Cells—animals submitted to cryoinjury, followed by myogenic precursor cells (C2C12) transplantation; Injury þ Cells þ LLLT—animals submitted to cryoinjury, fol- lowed by myogenic precursor cells (C2C12) transplanta- tion 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 þ 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 þ Cells þ LLLT group exhibited a decrease in myonec- rosis 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. © 2018 Wiley Periodicals, Inc. Key words: laser therapy; skeletal muscle; cell trans- plantation; myoblasts INTRODUCTION Skeletal muscle is composed of muscle fibers and satellite cells surrounded by extracellular matrix. Satellite cells are the stem cells of skeletal muscle and provide the capacity of adaptation and regeneration. These cells are undifferentiated and remain in a quiescent state until activated by different stimuli, such as repair after muscle transplantation, repair after exercised-induced muscle injury, the recovery of strength after atrophy due to disuse, and in cases of muscular dystrophy [1,2]. Following an injury, skeletal muscle tissue undergoes a repair process involving degeneration, inflammation, regeneration, fibro- sis, and remodeling. The activation of satellite cells is necessary for the genesis of new skeletal muscle fibers [3]. The therapeutic potential of satellite cells has been explored and described in several studies. The two keys to the treatment of muscular dystrophy are gene therapy and cell therapy (or cell transplantation) due to the increase myogenic capacity. Transplantation cells need to have myogenic potential and therefore must do at least one of the following: form new myofibers, generate new satellite cells, and incorporate their nuclei into the myofibers [2]. The main components of muscle regeneration are satellite cells and myoblasts. The inoculation of these cells has been performed in clinical trials. The first study involving myoblast transplantation in patients with Duchenne muscular dystrophy (DMD) demonstrated that transplan- tation can produce gene complementation; MT myofibers expressed donor-derived dystrophin in one of six patients after 6 months [4]. In another study, this occurred in eight of nine patients after 1 month [5]. One specific myoblast Conflict of Interest Disclosures: All authors have completed and submitted the ICMJE Form for Disclosure of Potential Conflicts of Interest and none were reported. Contract grant sponsor: UNINOVE; Contract grant sponsor: Conselho Nacional de Desenvolvimento Cient  ıfico e Tecnol ogico; Contract grant number: 305739/2014 RAMF; Contract grant sponsor: Coordenac ¸ ~ ao de Aperfeic ¸oamento de Pessoal do N ıvel Superior; Contract grant numbers: 1550120 LADS, 1183510 LADS, 1510536 BGR; Contract grant sponsor: Fundac ¸ ~ ao de Amparo  a Pesquisa do Estado de S~ ao Paulo; Contract grant number: 2014/12381-1 RAMF. Ã Correspondence to: Profa Dra. Raquel Agnelli Mesquita- Ferrari, Postgraduate Program in Biophotonics Applied to Health Sciences, Universidade Nove de Julho (UNINOVE), Rua Vergueiro, 235/249. CEP 01504001, S~ ao Paulo, SP, Brazil. E- mail: raquel.mesquita@gmail.com Accepted 13 January 2018 Published online in Wiley Online Library (wileyonlinelibrary.com). DOI 10.1002/lsm.22798 ß 2018 Wiley Periodicals, Inc.