Episkin, a reconstituted human epidermis for assessing in vitro the irritancy of topically applied compounds

The Episkin epidermal system is a reconstituted organotypic culture of human keratinocytes forming a multilayer differentiated epidermis on a collagen matrix. This standardized model was used to measure various parameters reflecting irritation observed in vivo following topical application of a variety of surfactants. A comparison of the results with historical data from ocular irritation testing in vivo showed a strong correlation for cytotoxic potential (r = 0.93; n = 23; P < 0.00001) and damage to the epithelial barrier function (r = 0.87; n = 20; P < 0.00001). In addition, the proportion of agents for which the irritative potential is underestimated is low. With regard to cutaneous irritation, the release of a major pro-inflammatory cytokine, interleukin 1alpha, correlated with the degree of irritation observed in vivo (r = 0.81; n = 20; P < 0.0001). Given its suitability to testing a wide variety of parameters reflecting irritation and the fact that all types of topical formulations can be applied to the reconstructed epidermal surface, the Episkin model should be particularly useful for assessing the tolerability of topical agents in vitro.