Effect of photobiomodulation (670 nm) associated with vitamin A on the inflammatory phase of wound healing.

Wound healing is a complex biological process with specific phases. Photobiomodulation (PBM) decreases the inflammatory infiltrate, stimulating fibroblast proliferation and angiogenesis, and therefore, is indicated for wound healing. Vitamin A is used to reverse the inhibitory effects on wound healing and accelerate the healthy granulation tissue. The study aimed to evaluate the effect of topical vitamin A and PBM (GaAlAs) in inflammatory phase of cutaneous wounds. Forty Wistar male rats were separated into four groups: (1) control (CG); (2) laser group (LG) GaAlAs, 670 nm, 30 mW, energy per point of 0.9 J, radiating by 1 point in 30 s; (3) vitamin A group (VitAG); and (4) laser group plus vitamin A (LG + VitAG). Wounds were surgically made by a punch biopsy with 10 mm of diameter on the back of the animals and all treatments were started according to the experiment. The treatments were administered for four consecutive days and biopsy was performed on day 4. We performed both H&E and immunohistochemistry analysis. The results were compared between groups by one-way analysis of variance ANOVA test with post hoc Tukey (p < 0.05). Inflammatory infiltrate increased significantly in LG compared to CG and VitAG (p < 0.05). Regarding angiogenesis, VEGF expression was increased significantly in LG and LG + VitAG groups, p < 0.01. The results indicate that proposed treatments were effective on the healing process improved by LG and LG + VitAG. We show that laser plus vitamin A enhances healing by reducing the wound area and may have potential application for clinical management of cutaneous wounds.

Photobiomodulation mechanisms in the kinetics of the wound healing process in rats.

OBJECTIVES: The healing process of cutaneous lesions is considered a complex event divided into distinct and overlapping phases, which responds satisfactorily to photobiomodulation (PBM). PBM is indicated as a therapeutic resource capable of assisting tissue repair. The present study aimed to analyze the kinetics of cutaneous wounds healing process after application of the GaAlAs laser for treating wounds on the dorsum of rats. MATERIALS AND METHODS: This study was approved by the Animal Ethics Committee of UFSCar. The animals were divided into 2 groups (n = 10); control group (CG) used 0.9% saline solution and the laser group (LG) used GaAlAs, 670 nm continuous pulse, 30 mW power, 14.28 J/cm2 energy density, irradiating 1 point per wound for 30s, totaling 15 consecutive days of treatment. Samples were collected on the 4th, 11th and 16th days for histological analysis of HE, Picrosirius-Red, immunohistochemistry (Collagen1, TNF-α, VEGF). Statistical analyzes used the one-way ANOVA test for intra and inter group evaluations, and the Tukey post-test. Level of significance was set at p < 0.05. RESULTS: The histopathological analysis (HE) showed a statistically significant difference for lower values of inflammatory infiltrate in LG versus CG on the 16th day; and for the increase of collagen in the 11th and 16th days of treatment. There was a statistically significant difference in the increase of VEGF on the 11th day for LG; decrease of TNF-α on the 4th and 11th day for LG, and increase of collagen type 1 on the 4th and 16th days for LG. The birefringence analysis of the percentage of collagen fibers presented on the 11th day of treatment revealed a greater quantity and significant statistical difference. Collagen fibers showed improved organization and arrangement on the 11th day for LG. CONCLUSION: Our results show that PBM is effective in helping the kinetics of the cutaneous wound healing process in rats and promotes the necessary stimuli for the satisfactory evolution of healing process, ultimately leading to structurally desirable tissue.