Nanostructured lipid carriers loaded with CoQ10: effect on human dermal fibroblasts under normal and UVA-mediated oxidative conditions.

Nanostructured lipid carriers (NLC) represent an emerging tool for drug delivery and are characterized by important features which promote increased bioavailability and epithelial penetration of lipophilic compounds. However, despite these advantages, their potential cytotoxicity should not be underestimated, especially under in vivo usage conditions. Here we analyzed the viability, intracellular reactive oxygen species (ROS), oxidative DNA damage and mitochondrial functionality in human dermal fibroblasts (HDF) in the presence of NLC either empty or loaded with the reduced or oxidized form of Coenzyme Q10. Experiments were carried out under standard culture conditions and under oxidative stress induced by UVA irradiation, where the latter treatment significantly affected all the endpoints tested above compared to the non-UVA condition. The data show that NLC alone, whether exposed or not exposed to UVA, produce a slight, though significant decrease in cell viability associated with enhanced oxidative stress, which did not however lead to oxidative DNA damage nor mitochondrial impairment. Reduced CoQ10-NLC, differently from oxidized CoQ10-NLC, were able to efficiently counteract UVA-associated mitochondrial depolarization suggesting a potential role of this molecule in antiageing cosmetological formulations. In conclusion, our results suggest that interactions of NLC with cells and biomolecules should be routinely assessed for understanding their compatibility and toxicity, not only under normal conditions, but also under any chemical or physical stress which these delivery systems might be subjected to during their employment.