Efeito da fotobiomodulação simultânea dos lasers vermelho e infravermelho na cicatrização por segunda intenção de feridas cutâneas

Abstract

The management of skin wounds requires strategies that can accelerate the repair of injured tissue. In this regard, the use of photobiomodulation therapy (PBMT) with the use of Light Amplification by Stimulated Emission of Radiation (Laser) in the red and near infrared wavelengths stands out. Therefore, the objective of this study was to evaluate the effect of photobiomodulation with isolated and simultaneous use of red and infrared lasers in healing by secondary intention of cutaneous wounds. The sample consisted of 60 Wistar rats, aged between 70 and 90 days, weighing between 250 and 350 grams, randomly divided into 4 groups: Control (CTRL) (n=15), Red Laser (RED) (n=15) , Infrared Laser (INFRA) (n=15) and simultaneous Red and Infrared Laser (SIM) (n=15), with subgroups (n=5) for each time of euthanasia (3, 7 and 14 days). Irradiation with Red Laser ( 630±10nm, 100mW, 10.16 J/cm2 per point, for 10 seconds), Infrared Laser ( 810±10nm, 100mW, 10.16 J/cm2 per point, for 10 seconds) and simultaneous Red and Infrared Lasers ( 630±10nm and  810±10nm, 100mW for each of the lights, 10.16 J/cm2 per point, being 5.08 J/cm2 for each of the lights, for 10 seconds ), were performed immediately after wound induction, in a punctual manner, at four equidistant points around the wound and a central point, and were repeated every 48 hours, with the exception of euthanasia days. The clinical aspects of the skin wounds were evaluated and, after the euthanasia of the animals, the Wound Retraction Index (WRI) was evaluated. After removing the specimens, histological sections stained with hematoxylin and eosin were evaluated for re-epithelialization (×100) and inflammatory infiltrate (×1000) under light microscopy. The immunoexpression of TNF-α and TGF-β1 was evaluated in cells from the connective tissue and from the epithelial lining of the wounds, establishing the percentage of positive cells for each of the antibodies (×400). VERM, at 7 days, induced better re-epithelialization and a higher IRF than the other treated groups. SIM and VERM animals showed better clinical healing of the wound at 14 days. The association of lasers seems to increase the acute inflammatory response, with greater expression of TNF-α, followed by a substantial reduction in the inflammatory infiltrate. At 3 and 7 days, INFRA showed higher expression of TGF-β1 in epithelial tissue, with a statistically significant difference in relation to CTRL (p=0.01), at 3 days. The SIM and VERM groups showed a lower expression of TGF-β1, especially in the last days of the healing process. In conclusion, PBMT with the use of lasers can stimulate wound contraction, re-epithelialization and modulate inflammation, with the infrared laser inducing a greater expression of TGF-β1, in the acute phase, and the red laser and the association of two lengths waveform, presenting itself as a therapeutic possibility in the reduction of tissue fibrosis.