Angionesis induced by low-intensity laser therapy: comparative study between single and fractioned dose on burn healing

Abstract

Severe burns cause extensive damage and are complicated by loss of body fluids, injury in the cutaneous vasculature and delayed wound healing. Low-intensity laser therapy (LILT) has been studied as an alternative method to accelerate wound healing. This study was carried out to evaluate LILT effects (λ= 660 nm) in rat burned skin with two different dose regimens. Thirty-six male adult Wistar rats with two burns created on their back using steam water were divided into 3 groups. In the fractioned dose laser group (FG), the lesions were irradiated with 1J/cm² on days 1, 3, 8 and 10; in the single dose laser group (SG), the lesions were irradiated with 4J/cm² on day 1. On control group (CG), lesions were not irradiated. Three animals per group were sacrificed on days 1, 3, 8, 10, 15 and 21 post-wounding and skin specimens were collected and processed to histomorphometry. At days 1, 3 and 8, statistical significant differences were not observed among groups. On the 10th day, mean values of the number of blood vessels for FG was significantly higher than CG. Irradiated groups showed a peak of new blood vessels formation at day 15 while for CG the peak was at day 21. The number of vessels in CG was significantly higher than FG and SG at day 21. These findings suggest that LILT may accelerate angiogenesis compared to control group, however, no significant differences were observed between laser groups with fractioned or single dose during all experiment.