The influence of low-level laser therapy on biomodulation of collagen and elastic fibers

Abstract

The study of low-level laser therapy upon extracellular matrix elements is important to understand the wound healing process under this agent. However, little is known about the interference of laser light in relation to collagen and elastic fibers. Cutaneous wounds were performed on the back of 72 Wistar rats and a Ga-Al-As low-level laser was punctually applied with different energy densities. The animals were killed after 24, 48, 72 hours and 5, 7 and 14 days. Tissues were stained with hematoxilin-eosin, sirius red fast green and orcein and then analyzed. It was observed that the treated group exhibited larger reduction of edema and inflammatory infiltrate. The treated animals presented a larger expression of collagen and elastic fibers, although without statistical significance (p > 0.05). Treatment with a dosage of 4 J/cm² exhibited more expressive results than that with 8 J/cm². In this study, the authors concluded that low-level laser therapy contributed to a larger expression of collagen and elastic fibers during the early phases of the wound healing process. DESCRIPTORS:Lasers; Laser therapy, low-level; Wound healing; Collagen. RESUMO:O estudo da terapia a laser de baixa densidade de energia sobre os diversos constituintes da matriz extracelular é crucial para o entendimento do processo cicatricial sob esse agente. Todavia, pouco se sabe sobre a interferên-cia do laser em relação às fibras colágenas e elásticas. Realizaram-se ferimentos cutâneos padronizados no dorso de setenta e dois ratos Wistar e, em seguida, aplicação pontual do raio laser de baixa potência do tipo Arseneto de Gá-lio-Alumínio (Ga-Al-As) com diferentes densidades de energia. Os animais foram sacrificados com 24, 48 e 72 horas e aos 5, 7 e 14 dias. Procedeu-se à análise das secções teciduais coradas por hematoxilina-eosina, sírius vermelho e orceína. Observou-se, que nos grupos submetidos à terapia a laser, houve maior redução do edema e infiltrado inflamatório. Os animais tratados apresentaram uma maior expressão de fibras colágenas e elásticas, embora sem significân-cia estatística (p > 0,05). No tratamento com a fluência de 4 J/cm² observaram-se melhores resultados do que naquele em que foi utilizada a fluência de 8 J/cm². Neste estudo, pôde-se concluir que o laser contribuiu para uma maior expressão de fibras colágenas e elásticas durante o processo cicatricial. DESCRITORES:Lasers; Terapia a laser de baixa intensidade; Cicatrização de feridas; Colágeno.

Effect of gallium-arsenide laser, gallium-aluminum-arsenide laser and healing ointment on cutaneous wound healing in Wistar rats

“…According to Medrado et al (14) and Pugliese et al (15), the use of GaAlAs laser at lower energy densities had a significant effect on the cicatrization of tissues, accelerating tissue repair through decreased edema, improved granulation tissue and fibroblast proliferation stimulation. In contrast to our results, they showed that 4 J/cm 2 laser is less effective for early wound closure during every experiment (15). According to Enwemeka et al (9) and Woodruff et al (16), the use of 632.8 and 780 nm laser therapy positively influences several tissue repair parameters, including reduced wound area and healing time, while the best energy density results range between 19 and 24 J/cm 2 and densities below 8.25 J/cm 2 and above 130 J/ cm 2 do not produce good wound closure results.…”

Effect of low level laser on sutured wound healing in rats

“…It is noteworthy that the predominance of type III collagen, provides a fragile scar on your tension, but on the other hand, excess type I collagen is responsible for a healing of poor quality, showing hypertrophic appearance. Notwithstanding increased collagen synthesis is considered a good marker of healing evolution, over deposition of these fibers within the wound area may provoke excessive accumulation of scar tissue, resulting in hypertrophic scars or keloids 18 . However, this undesirable effect can be minimized by applying correct dosages of Laser irradiation in order avoid over stimulation of fibroblastic activity.…”

Análise da dose do laser de baixa potência em equipamentos nacionais

“…In the same way, Pugliese et al 17 observed the influences of the GaAlAs laser on the biomodulation of elastic fibers and collagen in skin wounds in rats, concluding that 4 J/cm 2 was superior to 8 J/cm 2 . However, neither their study nor that of Matera et al 4 stated the parameters needed to arrive at the final energy, although Matera pointed out the importance of giving details about the dose.…”