INTRA- AND INTERLABORATORY REPRODUCIBILITY (ET-50) OF EPIDERM, AN IN VITRO MODEL FOR DERMAL IRRITANCY TESTING.

An in vitro model of the human epidermis, EpiDerm™, cultured from normal human epidermal keratinocytes (NHEK), was introduced by MatTek Corporation in April 1993. Using highly controlled tissue culture techniques, weekly batches of EpiDerm are produced for dermal irritancy testing, percutaneous absorption studies, and basic skin research. Histology, sterility, and the toxicological behavior are rigorously monitored on each batch. Histological evaluations show EpiDerm to be a highly differentiated skin-like structure which is very uniform within an individual batch and between batches. Over the first 13 months, random sterility checks at MatTek have shown no contamination and a single customer only once reported evidence of contamination. The toxicological behavior, monitored using the MTT Effective Time-50 Assay (ET-50), appears highly reproducible: the average coefficient of variation (c.v.) for exposure to the negative control (ultrapure water) was 6.46% and the average c.v. for exposure to the positive controls (1% Triton X-100 and 1% SDS) over a range of exposure times was 8.42%. Lot-to-lot MTT values for the negative control had a c.v. of 12.5% (N=26 batches) and the ET-50’s for Triton X-100 and SDS had c.v.’s of 13.9% and 21.1%, respectively. The average ET-50 measured at MatTek for Triton X-100 was 8.63 ± 1.20 hrs (N=26 batches) which compared closely to results at Microbiological Associates, Inc. which reported an average ET-50 of 8.14 ± 0.79 hrs (N=13 batches). Thus, EpiDerm appears to be highly reproducible both structurally and functionally and hence should be useful for toxicology and other skin related studies.

Cutaneous irritancy, Cutaneous irritation, Cutaneous toxicity, Dermal, Dermal absorption, Dermal irritancy, Dermal irritancy testing, Dermal irritation, Dermal penetration, Dermal permeation, Endpoints, MTT, EpiDerm, MTT, MTT ET-50 tissue viability assay, MTT assay, Percutaneous absorption, Percutaneous penetration, Reproducibility, Reproducible, Skin irritancy, Skin irritation, Sodium dodecyl sulfate (SDS), Transdermal