Effects of Laser Photobiomodulation on Cutaneous Wounds Treated with Mitomycin C: A Histomorphometric and Histological Study in a Rodent Model

Aim: The aim of the present study was to assess histologically the effect of Laser Photobiomodulation (LPBM) on skin wounds treated with Mitomycin C (MMC). Background Data: Wound healing occurs because of a competitive mechanism between the synthesis and lyses of collagen. Therefore, any factor that increases the lyses or reduces the synthesis of collagen may result in changes in the healing process. MMC is an antineoplastic drug that inhibits fibroblast proliferation, collagen synthesis, and neoangiogenesis. LPBM has been shown to stimulate wound healing, increasing the production of collagen, fibroblastic proliferation, and angiogenesis. Materials and Methods: Forty-eight Wistar rats were randomly distributed into 4 main groups (n = 12): G1 - control (G1a - 7 d and G1b - 14 d); G2 - MMC (G2a - 7 d and G2b - 14 d); G3 - MMC+lambda 660nm laser (G3a - 7 d and G3b - 14 d); and G4 - MMC + lambda 790nm laser (G4a - 7 d and G4b - 14 d). Under general anesthesia, one excisional wound was created on the dorsum of each animal. Two ml of MMC solution was applied to the wound 4 h after surgery for 5 min. LPBM was performed on groups G3 (lambda 690 nm; 20 J/cm(2); 30mW; Phi - 2mm) and G4 (lambda 790 nm; 20 J/cm(2); 40mW; F 2 mm), starting immediately after the application of the MMC and repeated every other day during the experimental period. Laser light was applied transcutaneously at 4 equidistant points on the wound margin (4x5J/cm(2), 20J/cm(2)/session). The specimens were routinely cut and processed to wax. The slides were stained with HE and Sirius red. Computerized hystomorphometry was performed. Results: LPBM resulted in reduced inflammation and an increase in both fibroblast proliferation and collagen deposition. Conclusion: The use of LPBM improves wound healing in subjects treated with MMC.