Influence of two systems of delivery of low-intensity laser in skin repair in diabetic rats: morphological evaluation, myofibroblasts and collagens I and III

Abstract

Tecidual repair of diabetic individuals is altered and often inefficient leading to the formation of chronic ulcers. Laser therapy is a promising tool to assist the closure of these wounds, but the lack of standardization of dosimetry, systems of energy delivery and lack of understanding of their cellular and molecular mechanisms of action limit the spread of its use. The objective of this study is to evaluate the repair tissue morphology of skin lesions of diabetic animals subjected to two regimes of delivery of laser light, namely: single dose and fractionated dose. This will be used 54 male Wistar rats (Rattus norvegicus Albinus) with diabetes induced by intraperitoneal injection of streptozotocin (50mg/kg). The ulcer will be made with a punch of 8 mm on the back of the animal after shaving. There will be three groups: (1) control group (CG) - the dorsal ulcer will not be subjected to treatment, (2) single dose (SDG) - dorsal ulcer will receive laser therapy two hours after the wound, (3) fractionated dose (FDG) - dorsal ulcer will receive laser therapy four times. The application of laser parameters are: four applications of » = (660 ± 2) nm, I = 6mW/cm2, D = 1 J/cm2 and t = 167 s in the FDG, and one application of » = (660 ± 2) nm, I = 6mW/cm2, D = 4 J/cm2 and t = 668 s in the group SDG. At the end of 0, 3, 7 and 14 days the animals will suffer euthanasia and ulcers removed, processed routinely for hematoxylin and eosin, Picrosirius and will be performed immunohistochemistry to detect myofibroblasts. The repair will be assessed by two calibrated raters without prior knowledge of the groups. The following parameters are assessed: the presence and type of inflammatory infiltrate, presence of granulation tissue, fibroblast alignment, number of myofibroblasts and remodeling of collagen I and III. The data will be evaluated for normality and subjected to appropriate statistical analysis.(AU)