In vitro dermal toxicology using skin organ cultures

In order to reduce animal discomfort and to obtain more quantitative endpoints, there is a need for reliable, preferably simple and inexpensive in vitro alternatives to skin toxicity testing. An in vitro model was developed in which full-thickness skin from various species can be cultured (rabbit, pig and human). Subsequent to topically applied test compounds, parameters of dermal toxicity were investigated, including cytotoxicity (MTT assay) and the release of inflammatory mediators (HETE's). Moreover, percutaneous absorption and concurrent biotransformation of compounds was studied. MTT conversion was inhibited in a dose-dependent manner following topical application of a wide range of irritants. Repair of initial damage was observed to some extent. The eicosanoid 12-HETE, which is thought to play an important role in chemotaxis, is released. Interestingly, the anti-inflammatory mediator 15-HETE was released only after a prolonged culture time of 48 hr, possibly indicating repair of the induced damage. The metabolic fate of the pesticide propoxur was investigated. Permeation rates were comparable in human and rabbit skin, while pig skin was found to be twice as permeable. Extensive cutaneous metabolism was observed in all three species.