Evaluation of the effects of polarized light (λ400-200 nm) on the healing of third-degree burns in induced diabetic and nondiabetic rats.

OBJECTIVE: The study evaluated, by light microscopy, the repair process on third-degree burns on diabetic and nondiabetic rats, illuminated or not, with a polarized light (PL) source. BACKGROUND DATA: Burns are severe injuries that result in the loss of fluid and destruction of tissue, infection, and shock that may result in death. Diabetes mellitus is a public health problem that, being uncontrolled, causes severe disturbance to the body metabolism, including on wound healing. PL sources have been shown to be effective in improving healing in many situations. MATERIALS AND METHODS: Ninety male Wistar rats were divided into two groups (n=45): nondiabetic and diabetic. In one of the groups, diabetes mellitus was induced by streptozotocin. A third-degree burn, measuring 1.5×1.5 cm(2), was created in the dorsum of each animal. Phototherapy (λ400-2000 nm, 10.2 or 20.4 J/cm(2)) started immediately after burning and was repeated daily until animal death (7, 14, and 21 days). Specimens were taken, processed, and stained with H&E and Sirius red and immunomarked with cytokeratin (CK) AE1/AE3. Descriptive analysis was performed by light microscopy. RESULTS: Animals subjected to phototherapy showed an acceleration of the repair, the dose of 10.2 J/cm(2) being the one that caused best results, including higher deposition of collagen, quicker inflammatory reaction, and improved revascularization. CONCLUSIONS: Our results suggest that the use of PL (10.2 J/cm(2)) improves the healing of third-degree burns on both diabetic and nondiabetic animals.