An ex vivo study of photobiostimulation in the treatment of skin pathologies.

Abstract

Photodynamic therapy (PDT) and low level laser therapy (LLLT) may mutually improve the outcomes on the healing process of chronic wounds and other skin pathologies, through processes known to stimulate the proliferation of dermal cellular structures, as well as antimicrobial application. This study proposes the use of nanoemulsion containing aluminium phthalocyanine chloride (ClAlPc) as photosensitizer (PS), to establish the most appropriate protocol for photostimulation in human skin biopsies, associated to type I collagen and elastin production. The combined effect of PS and light (diode laser at 670nm) at three different doses is compared to the effect of light itself at doses of 70, 140 and 700mJċcm-2 , 7 and 14 days after irradiation. Histological analysis reveals the increase in collagen and elastin, higher than 20%, 14 days after treatment with PS and light at 140mJċcm-2 . Higher doses of light promote an inhibitory effect, leading to tissue degradation. In addition, the expression levels of the enzymes MMP-2 and MMP-9 (Gelatinases A and B - participant in various processes including tumoral progression and wound healing) are detected by gelatin zymography, reinforcing the efficacy of the combined treatment with PS and light at the intermediate dose.