Pinheiro ALTA, Facchini G, Clerici SP, Eberlin S, Pinheiro AS, Eberlin S.
For a long time it was believed that skin photoaging were exclusively attributed to ultraviolet radiation, but lately infrared radiation A (IRA) has attracted interest from scientific community for induce similar skin structural changes to those observed by prolonged exposure to ultraviolet radiation. With the advent of 3Rs policy (Replace, Reduce and Refine), the applied research to cosmetic market on the understanding of this photoaging provided by IRA were restricted to in vitro and clinical testing. The evaluation of the biological mechanisms using as test system skin biopsies obtained from human volunteers is a model for understanding the damage triggered by an aggressing agent. However, this procedure can be considered invasive as ordinary research tool. In this sense, an alternative to fill this gap between in vitro and clinical is the use of skin fragments from elective plastic surgery (ex vivo study). The objective of this study was to correlate the effects of IRA radiation in biopsies, ex vivo skin fragments and human fibroblasts cultured, through the quantification of MMP-1, TIMP-1 and GADD45a mediators. Biopsies of human skin, as well as the human skin fragments originating from elective plastic surgery, were obtained after approval of the ethics committee and voluntary consent. Together with cultured human fibroblasts (HFF-1), these tests systems were incubated for 48 hours at 37°C in a humidified atmosphere with 5% CO2. After, they were exposed to a dose of 360 J/cm2 infrared-A radiation using Hydrosun 750 and HBM1 devices (Hydrosun Medizintechnik GmbH, Müllheim, Germany). After irradiation, tests systems were incubated with fresh culture medium and maintained for 24 hours to collect the culture supernatant and quantification of MMP-1, TIMP-1 and GADD45a by enzyme-linked immunosorbent assay. The results demonstrated that the three models used, IRA radiation induced increase in MMP-1 and did not alter the values of this protease inhibitor (TIMP-1). A similar effect can be observed with the GADD45a protein, since radiation was able to inhibit the synthesis of this cellular stress sensor in the biopsies, fragments ex vivo and in cell culture. Therefore, due to the positive correlation of results between three models studied, it may be suggested that an alternative approach to human biopsies is the use of ex vivo model, once is characterized as a plausible and sustainable tool to address the differences between the knowledge generated from in vitro and clinical experiments.