EPIOCULAR PREDICTION MODEL. A REPRODUCIBLE IN VITRO TISSUE CULTURE MEANS OF PREDICTING DRAIZE SCORES.

• TR Number: 142
• Authors: Kubilus, J., Sennott, H., Makwana, A., Klausner, M. Mattek Corp., Ashland, MA.

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. Parafin embedded, H&E stained histology cross-sections show the structure of EpiOcular closely parallels that of the HCE; large nucleated basal cells lie beneath 5-6 stratified cell layers which progressively flatten out, ending with a highly squamous, non-keratinized layer at the culture’s apical surface. Using the MTT ET-50 cytotoxicity assay, 28 materials from the ECETOC ocular database were tested with the OCL-200 and the in vitro results were correlated to the Draize scores available from the data base; a linear plot of log ET-50 versus log Draize gave a correlation coefficient, r = 0.90. This correlation was then used to develop the “prediction model” from which a Draize score could be calculated based on an ET-50. To probe the utility of the prediction model, 33 materials including surfactants, final formulation shampoos, and off-the-shelf cosmetic products for which Draize data were available, were tested. The predicted and actual Draize scores were compared and a resulting correlation coefficient of r = 0.85 was obtained. Thus, the EpiOcular tissue model appears to be a facile, in vitro means to reduce and/or replace in vivo, animal-based ocular irritancy testing.