Effects of Different Protocols of Low-Level Laser Therapy on Collagen Deposition in Wound Healing

Abstract

The low-level laser has proven successful in stimulating the production of collagen in wound healing assays. However, diversity has been observed in the protocols used. This work has evaluated the effects of three protocols of low-level laser therapy (LLLT) in the healing of open wounds in rats. Standard-sized wounds of 1 cm2 were performed with a scalpel in the middorsal region of 60 male Wistar rats weighing 225±25 g, and they were assigned into four groups (n=15): CTR (non-irradiated animals), LT1 (20 J/cm2 daily), LT2 (16 J/cm2 daily) and LT3 (20 J/cm2 daily). After 7, 14 and 21 days, five animals/day were euthanized and the wounds analyzed histologically. Data were subjected to normality analysis of distribution using Shapiro-Wilk test. Gaussian data were analyzed using ANOVA and Bonferroni tests whereas non-Gaussian data were analyzed using Kruskal-Wallis and Dunn tests, considering significant p values less than 0.05. The LLLT in all protocols reduced the inflammation and collagen deposition increased significantly (p<0.05). However, LT2 showed the highest levels of collagen in all phases of the study (p<0.05) induced faster replacement of immature collagen III by mature collagen I in the early stages of repair and early collagen remodeling promoted by providing better organization architectural beams deposited. It was concluded that all protocols induced an increase in collagen scar. However, the protocol 2 (16 J /cm2, daily application) promoted the most significant increases in collagen deposition, accelerated maturation of collagen and showed the best architecture of the final fibrous scarring.

Histological Evidence of Wound Healing Improvement in Rats Treated with Oral Administration of Hydroalcoholic Extract of Vitis labrusca

“…Over the time-course of wound healing the matrix deposited in the wounded area undergoes important changes in its composition. With the closure of the wound, type III collagen is gradually degraded, whereas synthesis of type I collagen increases [45], just as observed in the current study. Type I collagen accumulation speeds up reaching a peak at around day 10-14 when it accounts for at least 75% of total collagen in the granulation tissue [41].…”

Photobiomodulation invigorating collagen deposition, proliferating cell nuclear antigen and Ki67 expression during dermal wound repair in mice

“…The early replacement of type III collagen with type I collagen in healing tissue witnessed in the current inedited report could be linked to the exposure of an optimum dose of 632.8-nm laser, thereby augmenting the wound repair process. The findings of the current work on the early replacement of type III to type I collagen is entirely corroborated with an earlier published report [41]. Our assumption that a raise in collagen noticed in the current investigation is directly linked with an increase in the number of fibroblasts, as depicted in several other studies with other illuminated wavelengths [38,[42][43][44][45].…”

Experimental Study of the Effect of Photobiomodulation Therapy on the Regulation of the Healing Process of Chronic Wounds

“…Thus, after four treatment sessions carried out in the first days after wound induction, a more pronounced expression of collagen fibers was observed in rats receiving PBM therapy, compared with the control group on days 14 and 21 [17]. The results of another study also demonstrate accelerated maturation and increased collagen deposition and better architecture of final fibrous scarring at 21 days after injury, following daily application of PBM therapy during the first 7 days after wound induction [18]. In our work, we investigated the effect of PBM therapy, applied in the first 5 days after wound modeling, on the reparation processes of chronic wounds at all stages of wound healing, including the long-term effects of this method on days 14 and 28.…”