Protective effects of Polypodium leucotomos extract against UVB-induced damage in a model of reconstructed human epidermis

Background Polypodium leucotomos (PL) exerts potent antioxidant, photo-protective, and immune-modulatory activities. A reconstructed human epidermis (RHE) (Episkin) is a suitable model for the evaluation of acute UV-induced cell damage. No data regarding the photo-protective action of PL in this model are available. Purpose We evaluated the effects of PL on the prevention of UVB-induced cell damage assessing sunburn cells, CPD formation, p53, Ki-67, p21 expression, and epidermal growth factor (EGF) production. Materials & Methods RHE was incubated in standard conditions. PL was topically applied at the concentration of 2 mg/cm(2), immediately before UVB exposition. UVB exposition (300 mJ/cm(2)) was performed using a dedicated UVB lamp. Irradiated samples without PL and non-irradiated samples were used as positive and negative controls. Expression of p53, p21, and Ki-67 was evaluated with immune-histochemical methods. CPD were measured using a monoclonal antibody. Results PL significantly reduced sunburned cells (-80%) in comparison with positive control. PL significantly prevented the increase in EGF production at tested times. PL significantly reduced the p53 (-80%), p21 (-84%), and Ki-67 (-48%) positive cells. Finally, PL prevented the formation of CPD (0% vs. 20% positive cells). Conclusion In this model, PL has shown to prevent UVB cell damage, the upregulation of proliferating proteins, and fully blocking the formation of CPD.