Prevalidation of a new in vitro reconstituted human cornea model to assess the eye irritating potential of chemicals

This multicentre study aimed at evaluating the reliability (reproducibility) and relevance (predictivity) of a new commercially available human corneal epithelial (HCE) model (SkinEthic Laboratories, Nice, France) to assess acute ocular irritation. A prevalidation approach (protocol optimisation, transfer and performance) was followed and at each of the four participating laboratories, 20 coded reference chemicals, covering the whole range of irritancy, were tested. The compounds were applied topically to the HCE cultures and the level of cytotoxicity (tissue viability and histological analysis) was determined. Once a standardised protocol was established, a high level of reproducibility between the laboratories was observed. In order to assess the capability of the HCE model to discriminate between irritants (I) and non-irritants (NI), a classification prediction model (PM) was defined based on a viability cut-off value of 60%. The obtained in vitro classifications were compared with different in vivo classifications (e.g. Globally Harmonised System) which were calculated from individual rabbit data described in the ECETOC data bank. Although an overall concordance of 80% was obtained (sensitivity = 100% and specificity = 56%), the predictivity of the HCE model substantially increased when other sources of in vivo and in vitro data were taken into account.