An organotypic model of skin to study photodamage and photoprotection in vitro.

Acute or repetitive sun exposures are known to elicit cutaneous damages such as sunburn but also long-term effects such as photoaging or cancers. Determination of early biological events occurring after ultraviolet (UV) exposure is essential for photoprotection. Using skin reconstructed in vitro containing both a dermal equivalent and a fully differentiated epidermis, the effects of UV light (UVB and UVA) were investigated. UVB-induced damage was essentially epidermal, with the typical sunburn cells and DNA lesions, whereas UVA radiation-induced damage was mostly located within the dermal compartment. The model and end points used for UVB- and UVA-induced damages appeared to be very useful for the in vitro evaluation of sunscreens after topical application, in particular to investigate its protective effects against the effects of UVR, and allowed us to distinguish the efficiency of absorbers depending on their absorption spectrum.