A REPRODUCIBLE SKIN MODEL FOR DERMAL SAFETY AND EFFICACY TESTING.

• TR Number: 209
• Authors: Klausner, M., Kubilus, J., Hayden, P., Sheasgreen, J. Mattek Corp., Ashland, MA.

The utility of any toxicological test system or method critically depends on the short and long term reproducibility of the method. Over the past 6 years, histological observations and quantitative quality control test methods utilizing the MTT assay have established a high level of intra-lot and inter-lot reproducibility for Mattek’s organotypic skin model, EpiDerm™. Interestingly, the MTT assay can distinguish between standard EpiDerm (EPI-200) and hydrocortisone free EpiDerm (EPI-200-HCF) whereas histologically, the tissues are remarkably similar. Quality control testing on each lot of tissue consists of exposing the tissue to 1% Triton X-100 (TX) and a negative control (NC), ultrapure water. Using the MTT assay, an exposure time which reduced the tissue viability to 50% (ET-50) was determined. For EPI-200 produced in 1995 (112 lots), the ET-50 for TX averaged 6.64+0.79 hrs; the optical density (OD) for NC was 1.495+0.126; during the first 9 months of calendar year 2000 (89 lots), the averages were 6.76+1.11 hrs and 1.627+0.164, respectively. For EPI-200-HCF, used for cytokine release studies, the ET-50 averaged 9.02+1.16 hrs and the NC was 1.490+0.165. Assays for dermal irritancy, corrosivity, and phototoxicity have been developed using EpiDerm. Correlation of in vivo irritation data to in vitro assay results for 4 sets of materials gave correlation coefficients of 0.85 and 0.96. For corrosivity, sensitivity of 87.5%, and specificity of 86.1% were obtained in a multi-lab, international blinded study of 24 unknowns. In a similar multi-lab phototoxicity study on 10 blinded materials, the sensitivity and specificity were 86.7% and 93.3%, respectively. Thus, the EpiDerm tissue model provides a reproducible, non-animal means to test materials and/or products for a variety of skin related issues.