Angiogênese em feridas cutâneas de ratos diabéticos – efeito da fotobiomodulação na expressão de fator de crescimento do endotélio vascular e de actina de músculo liso

Abstract

Diabetes mellitus (DM) is a chronic disease caused by both insufficient insulin production and peripheral resistance to insulin. This condition generates hyperglycemia with serious consequences, especially in tissue healing. In this context, the process of formation of new vessels, or angiogenesis is greatly affected. Low-intensity laser photobiomodulation (PBM) has been associated to improvements in both angiogenesis and tissue repair. To understand part of these mechanisms of PBM in diabetic animals, this study evaluated whether PBM causes difference in the expression of vascular endothelial growth factor (VEGF) and mature vessels that express smooth muscle actin (SMA) in cutaneous wounds. Ten Wistar rats were used from the UNINOVE breeding stock. Diabetes was induced with streptozotocin (50 mg/kg) and fifteen days after induction the diabetic animals were anesthetized and two dorsal ulcers were made with 8 mm punch. The animals were randomly divided into 2 groups: Control (untreated ulcer), Laser (laser therapy shortly after performing ulcer using diode laser, λ = 660 ± 2 nm, with output power equal to 100 mW and beam area of 0,04 cm2– Therapy XT, DMC, São Carlos, Brazil), with irradiance of 32.7 mW/cm2 for 122 s, delivering a dose of 4 J/cm2. Euthanasia was done 15 days after the injury. Samples were routinely processed for paraffin inclusion and staining with hematoxylin and eosin, immunohistochemistry for SMA and VEGF. The vessels were counted using ImageJ software and the data analyzed statistically. There was no statistical difference between the number of VEGF-labeled blood vessels between the control and laser groups (p = 0.22 - Mann-Whitney test). The amount of mature pots labeled with SMA was also similar between the groups (p = 0.36 - Mann-Whitney Test). Under the study conditions, at 15 days of tissue repair of diabetic rats, photobiomodulation did not cause any difference in angiogenesis