Influência do laser vermelho de baixa potência no processo de reparo de queimaduras de segundo grau

Abstract

The aim of this study was to investigate the effects of low-level red laser on tissue repair in rats submitted to second degree burn, evaluating if the timing of laser treatment influence on the healing process and investigate the expression of the genes involved with DNA repair by base excision and nucleotide excision pathways. The animals had their backs shaved and divided as follows: control group (n = 12) - rats burned and not irradiated, early laser group (n = 12) - rats burned and irradiated from day 1 after injury for 5 consecutive days, and late laser group (n = 14) - rats burned and irradiated from day 4 after injury for 5 consecutive days. Laser irradiation was according to a clinical protocol (20 J/cm2, 100 mW, continuous wave emission mode, 660 nm) as recommended by the laser device manufacturer. Half of the animals were sacrificed 10 days after burn and the other animals were sacrificed 21 days after burn. Late laser group accelerated wound contraction 10 and 21 days after burn. Late laser group accelerated reepithelialization 18 days after burn. Late laser group increased the granulation tissue 10 and 21 days after burn. Both irradiated groups increased type III collagen expression and TGF-β 21 days after burn. Both irradiated groups increased macrophages and myofibroblasts number 10 days after burn, and decreased 21 after days. Low-level red laser exposure reduced the expression of APE1 messenger (mRNA), increased the expression of OGG1, reduced the expression of XPC and increased the expression of XPA in both irradiated groups laser and later laser groups. Low-level red laser exposure contributes to the process of tissue repair of second degree burns, suggesting that the intervention during proliferative phase is crucial in the final outcome of the repair process. Moreover, the therapeutic laser was capable of altering the expression of genes involved in DNA repair.