Avaliação dos efeitos de extrato da própolis vermelha na proteção de células epiteliais e mesenquimais humanas induzidas com irradiação UVA

Abstract

The skin is a tissue directly exposed to external chemical and physical factors that lead to the development of different skin lesions. The protection of this tissue against the most penetrating and harmful radiation, such as type A ultraviolet radiation (UVA), has been extensively explored in research. In addition to studies focused on therapeutic applications through tissue regeneration, alternative formulations based on extracts of natural products have emerged to prevent the development of skin lesions. Red propolis is an example of several products that have been used due to their antioxidant, antiinflammatory, antimicrobial, angiogenic and proliferative biological properties. In this context, it is important that study models that mimic the tissue organization of the in vitro tegument increasingly come closer to in vivo conditions. The objective of this study was to evaluate the effects on cell viability and programmed cell death in 2D and 3D culture models of previously treated skin keratinocyte lines (HaCat) and mesenchymal stem cells (MSCs), after exposure to red propolis extracts. and type A ultraviolet irradiation. The protective effect of Brazilian red propolis extracts against UVA irradiation (3.4Jcm³) was evaluated, as well as their phototoxicity at concentrations of 10, 25 and 100μg/mL during 2 hours of treatment. The results showed that only the 100μg/mL concentration tested had a cytotoxic effect on HaCats and MSC cells. Cell viability remained above 80% at the lowest concentrations (up to 25 μg/mL) for the cells tested, in all periods (24h, 72h and 168h) of analysis. 3D cultures of both strains showed greater resistance to cell death in all conditions tested when compared to 2D cultures and controls. The results provide evidence that the use of red propolis extracts favors the strains and models tested. It is possible that the increase in the percentage of cells that survive after exposure to UVA irradiation in this study reflects the induction of cell proliferation, as the number of apoptotic cells was shown to be very small and its decrease would not cause a change significant enough to be detected by apoptotic induction assay. The tests showed an adaptive response of these cells when exposed to low doses (up to 25 μg/mL) of UVA irradiation, in addition to demonstrating the protective effect of propolis when irradiated. These results corroborate previous analyzes that have already been evaluated by our research group, which suggest that the use of red propolis extracts in low concentrations (< 25 μg/mL) is safe to be applied to different cell lines. In vitro studies with pre-treated three-dimensional models seek a better understanding of cellular relationships and a perspective to support reparative/reconstructive medicine, aiming at the recovery of patients who have suffered skin injuries or burns. [resumo fornecido pelo autor]