Characterization and applications of human epidermis reconstructed in vitro on de-epidermized derma

In recent years in vitro models have been developed to avoid the use of animals in cutaneous toxicological studies. Submerged human keratinocyte cultures in vitro could be so far employed as an alternative to animal testing and a good correlation between skin irritation and cytotoxicity has been demonstrated. Nevertheless, these submerged cultures are lacking in the stratum corneum which acts as a barrier to chemical toxicity, so that this type of culture is far from the in vivo situation. A better alternative method seems to be the use of in vitro reconstructed skin at the air-liquid interface that closely resembles the in vivo situation. In this work, in a first step we have characterized human epidermis reconstructed in vitro on de-epidermized derma (DED) after a two-week air exposure. Human skin reconstituted in vitro on DED was histologically similar to the in vivo skin. A stratified epidermis including the stratum corneum was obtained. The presence of basal lamina as well as of various important markers for epidermal differentiation (involucrin, K10 keratin, and filaggrin) were revealed. In a second step we have tested the cytotoxic and morphological effects of four surfactants on our model. A good rank correlation has been shown to exist between the irritation potency of surfactants on our model and reported ocular irritancy in vivo. From our results, in vitro reconstituted human skin could represent an attractive model for irritancy testing and could be an in vitro replacement for animal testing.