LONG TERM REPRODUCIBILITY OF EPIDERM, AN EPIDERMAL MODEL FOR DERMAL TESTING AND RESEARCH.

This technical reference summarizes MatTek’s 10-plus YEAR EpiDerm tissue reproducibility data. Long-term reproducibility is important not only to MatTek Customers, but also to European (ECVAM) and US (ICCVAM) regulators. Regulators constantly stress the need for superior reproducibility of in vitro tissue equivalents, not only during a specific validation program, but also long after the initial validation has been completed. An in vitro model of human epidermis, EpiDerm™ (EPI-200), cultured from neonatal, normal human epidermal keratinocytes has been sold commercially by MatTek Corporation since 1993. Using serum free medium, weekly lots of EpiDerm are produced and shipped for dermal irritancy, product efficacy, percutaneous absorption, pharmacological and basic skin research studies. In 2000 and 2002, respectively, European and US regulators approved the use of EpiDerm to assess the skin corrosivity of chemicals. Validation studies utilizing EpiDerm for phototoxicity and skin irritation are currently underway. For commercial and regulatory purposes, it is crucial that the model is reproducible both within a given lot and between lots, especially over extended periods. To address tissue reproducibility, quality control testing of each EpiDerm lot involves exposure to the surfactant, 1% Triton X-100, and a negative control, ultrapure water. Using the MTT assay, that historically has been the in vitro endpoint of choice for European and US regulators, a dose response curve is constructed and an exposure time which reduces the tissue viability to 50% (ET-50) is interpolated. The yearly average ET-50 since 1996 has varied from 6.5 hr (2000) to 7.5 hr (1998). The coefficients of variation (CV) for the negative control have averaged under 7% for every year since 1997 and the average CV for all tissues has never exceeded 13.2%. Using light microscopy, histological H&E cross-sections show an epidermis-like morphology that is reproducible both within and between lots. Hence, over the past 10+ years of commercial production, EpiDerm has remained a highly reproducible, stable toxicological model that is ideally suited for industrial and regulatory toxicology and other skin related studies.

Air liquid interface (ALI), Basic skin research, Dermal irritancy, ECVAM, EPI-200, ET-50, EpiDerm, GLP, GMP, Good laboratory practice (GLP), Good manufacturing practice (GMP), Inter-lot reproducibility, Intra-lot reproducibility, MTT, MTT assay, Normal human epidermal keratinocytes (NHEK), OECD, Percutaneous absorption, Pharmacological research, Phototoxicity, Product efficacy, Reproducible model, Skin corrosivity, Skin irritation, Stable toxicological model, Triton X-100, Validation studies

Triton X-100