Development of a highly sensitive in vitro phototoxicity assay using the SkinEthic reconstructed human epidermis.

The reconstituted human epidermis model SkinEthic was used to evaluate the phototoxicity of topically applied chemicals. For comparison with published data, we first tested a library of 13 nonphototoxic (NPT) and phototoxic (PT) compounds, applied onto SkinEthic reconstituted human epidermal tissues, in a protocol as close as possible to the one described by Liebsch using another skin tissue model. The results showed that, under these nonoptimized conditions, the SkinEthic model was already able to fully discriminate between known NPT and PT compounds. Furthermore, these epidermal tissues being highly resistant to UVA irradiation, it was possible to increase irradiation by (at least) 3-fold without decrease in tissue viability. In such conditions, the phototoxicity assay is much more sensitive, so that the model is expected to be of great interest for the detection not only of strong but also of weak phototoxic compounds.