THE EPIOCULAR PREDICTION MODEL – A REPRODUCIBLE IN VITRO MEANS OF ASSESSING OCULAR IRRITANCY POTENTIAL.
The EpiOcular™ tissue model (OCL-200) is an organotypic model of the human corneal epithelium (HCE) cultured from normal human keratinocytes using serum free medium. Paraffin embedded, H&E stained histological cross-sections show the structure of EpiOcular closely parallels that of the HCE. During 1996 and 1997, 47 and 82 lots, respectively, of the OCL-200 model were produced and monitored using the MTT assay. The common surfactant, Triton X-l00 (0.3%), was used as a positive control and the Effective Time-50 values (time of exposure after which viability is reduced to 50%, or ET-50) was determined for each lot of tissue. The ET-50 average of 24.9 + 6.3 minutes (+ 1 standard deviation) for 1996 (n=47 lots) was not statistically different (p < 0.05) than the 1997 average of 22.9 + 4.7 minutes (n = 81 lots). Stability of the EpiOcular model for international shipment was probed using these standard quality control tests following packaging and storage of the tissue for 4 days; both positive and negative controls and histology of the tissue remained constant. Interlaboratory testing also confirmed the reproducibility of the tissue. Coefficients of variation (c.v.) for 3 materials tested in 3 laboratories were all below 10%. ET-50 values were measured for 19 water-soluble chemicals from the ECETOC database and 41 materials including final formulation shampoos, off-the-shelf cosmetic/personal care products, and surfactants. Draize data for these materials were correlated to ET-50 values and a prediction model was constructed: Draize = 4.735+l01.65/(ET-5O)^0.5 (correlation coefficient, r = 0.90). Thus, the EpiOcular tissue model is reproducible and appears to be an accurate in vitro means of predicting in vivo ocular irritancy.
Correlation coefficient, ECETOC database, EpiOcular, Eye irritation, International shipment, MTT, MTT ET-50 tissue viability assay, MTT assay, Ocular irritancy testing, Ocular irritation, Ocular irritation testing, Positive control, Reproducibility, Reproducible
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