Influence of low level laser therapy on wound healing and its biological action upon myofibroblasts

Background and Objective: In re-evaluating the effects of laser therapy in wound healing, the role of extracellular matrix elements and myofibroblasts, was analyzed. Study Design/Materials and Methods: Cutaneous wounds were inflicted on the back of 72 Wistar rats. Low level laser was locally applied with different energy densities. Lesions were analyzed after 24, 48, 72 hours and 5, 7, and 14 days. Tissues were studied by histology, immunohistochemistry, and electron microscopy. Results: In treated animals, the extent of edema and the number of inflammatory cells were reduced (P < 0.05), but the amount of collagen and elastic fibers appeared slightly increased. Desmin/smooth muscle alpha-actin-phenotype myofibroblasts were statistically more prominent on the 3rd day after surgery (P < 0.05) in treated wounds than in controls. Treatment with a dosage of 4 J/cm(2) was superior to that with 8 J/cm(2). Conclusions: Laser therapy reduced the inflammatory reaction, induced increased collagen deposition and a greater proliferation of myofibroblasts in experimental cutaneous wounds. (C) 2003 Wiley-Liss, Inc.