THOR VitroDerm RhE test method for skin irritation testing

The Thor Vitroderm model is a 3-d reconstructed human epidermis seeded on a polycarbonate filter and cultured at the air liquid interface. After 17 days, highly differentiated and stratified epidermis has developed which comprises a proliferating basal cell layer of columnar epithelial cells, giving rise to morphologically distinct suprabasal spinous and granular layers and a functional stratum corneum.

The purpose of the test method is for the prediction of acute skin irritation of chemicals applied topically to the apical surface of a reconstructed human epidermal model, by the measure of cytotoxicity by the MTT viability assay. The principle of the RHE model test is based on the premise that irritant chemicals are able to penetrate the stratum corneum and are cytotoxic to the cells in the underlying layers. Cell viability is measured by dehydrogenase conversion of the vital dye MTT [3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide, Thiazolyl blue; EINECS number 206-069-5, CAS number 298-93-1)] into a blue formazan salt that is quantitatively measured after extraction from tissues.