Efeitos da terapia de fotobiomodulação com leds azul e verde na deposição de colágeno em queimaduras de terceiro grau: um estudo pré-clínico

Abstract

The healing of third-degree burns represents a clinical challenge due to the intense inflammatory response, risk of infection, and tendency to form hypertrophic scars. Photobiomodulation therapy using Light Emitting Diode (LED) has emerged as a promising complementary alternative due to its ability to modulate cellular processes involved in tissue repair. Considering the essential role of collagen in the structural organization of the extracellular matrix, this study aimed to evaluate the effects of blue (470 nm) and green (520 ± 30 nm) LEDs on collagen deposition in third-degree burn healing. Sixty male Wistar rats were divided into three experimental groups: control (CRTL), blue LED (AZUL), and green LED (VERD). The rats were euthanized at 7, 14, 21, and 28 days (n=5 per subgroup). Applications were performed daily at four coincident points of the wound. The protocol for the blue LED was 470 nm, 1 W, 0.44 W/cm², 12.5 J/cm² per point 28 s, totaling 50 J/cm². For the green LED, 520 ± 30 nm, 180 mW, 60 J/cm² per point 120 s, totaling 240 J/cm² were used. The histological sections stained with Masson's trichrome were scanned (Motic EasyScan Pro 6) and analyzed in the DSAssistant and ImageJ® software, using segmentation by color clusters to quantify collagen fibers and total collagenization. The data were subjected to statistical analysis by the Kruskal-Wallis test, and Dwass-Steel-Critchlow-Fligner post-test, adopting a significance level of 5% (p<0.05). The results showed that, at 7 and 14 days, there were no statistically significant differences between the groups regarding thin collagen deposition (p>0.05). However, at 21 days, the BLUE group presented a smaller area collagenized by thin fibers compared to the control group (p=0.043), in addition to significantly lower values of thick collagen compared to the VERD group (p=0.024). At 28 days, although no isolated statistical differences were observed in thin or thick fibers (p>0,05), the VERD group presented greater thin collagen deposition. Regarding total collagenization, a significant reduction was observed in the BLUE group at 14 days (p=0.043), a pattern that remained at 28 days, with the lowest values of the study, significantly lower than the CRTL and VERD groups (p=0.024). Thus, it is concluded that blue LED photobiomodulation therapy impaired collagen deposition at different stages of tissue repair, especially in the final phase, suggesting a possible antifibrotic effect. On the other hand, green LED demonstrated favorable performance, tending to promote greater collagen organization and deposition, especially in the later stages of healing, reinforcing its therapeutic potential in modulating the repair of deep burns.