Under ISO 10993-23, skin irritation testing can now be performed using in vitro testing methods based on Reconstructed human Epidermis (RhE) models for medical device biocompatibility evaluation. Test materials are extracted into physiological saline and sesame oil (extraction performed under ISO 10993-12). Using the MTT reagent, tissue viability is assessed at the completion of the exposure time specific to each tissue model used. Since in vivo skin irritation typically results from chemical-induced cell damage and subsequent inflammatory cascade, this test method provides a mechanistically-relevant measurement of cell viability in RhE tissues after a single topically-applied treatment, relative to negative control-treated tissues. A relative viability of greater than 50% indicates a negative response for skin irritation induced by the medical devices. Studies are performed under GLP guidelines.