Efeito da fotobiomodulação no infiltrado inflamatório em feridas de pele de ratos diabéticos em dois regimes de entrega de energia

Abstract

The healing process of diabetic individuals is altered and is often ineficiente, leading to significant post-surgical complications such as delayed repair, dehiscence and infection. Laser therapy is a promising tool to assist the closure of these wounds, but the lack of standardization of dosimetry, of the power delivery systems and a lack of understanding of the cellular and molecular mechanisms of action limit the spread of its use. Studies indicate that modulation of macrophages and other inflammatory cells in certain stages of tissue repair induce more effective healing of the injury. The aim of this study was to compare two different regimes of application laser analyzing the influx of neutrophils, T lymphocytes, fibroblasts and total macrophages and M2 macrophages. 90 female Wistar rats were used, with body weight between 140 g and 250 g with diabetes induced by intraperitoneal injection of streptozotocin (50mg/kg) and back injuries made with surgical punch. The animals were divided into control group (CG - no treatment), Single Dose Group (SDG - 1 Application 4 J/cm²) and Fractionated Dose Group (GDF - 4 applications of 1 J/cm² at 1, 3, 8 and 10 days and undergoing laser therapy with 660 nm and 30 mW. After treatment, the lesions were removed and placed in buffered formalin 10% solution and routinely processed for paraffin inclusion, and then histologic staining with hematoxylin & eosin, immunohistochemical staining for T lymphocytes, total macrophages, M2 macrophages, neutrophils and myofibroblasts. The samples were photographed, the cells quantified, and subjected to appropriate statistical tests. The laser application in both groups accelerated the wound closure in 40% during the first 3 days. SDG presented a higher number of neutrophils in the first day, more macrophages on Day 3, more M2 macrophages on Day 8. The T lymphocyte count was similar in all groups during the experimental. Compared to controls, the laser treated groups presented more myofibroblasts on Day 15 and more collagen organization on Day 22. The results showed that photobiomodulation can alter the inflammatory

infiltrate composition of the diabetic wounds, especcially with a single dose application of the 4 J/cm².