Establishment and performance assessment of an in-house 3D Reconstructed Human Cornea-Like Epithelium (RhCE) as a screening tool for the identification of liquid chemicals with potential eye hazard

The objective of this project was to develop an in-house 3D Reconstructed Human Cornea-Like Epithelium (RhCE) to be used as a screening tool in early stages of product development. This study reports the establishment of the experimental procedure and the performance assessment of the model to discriminate liquid chemicals classified as causing serious eye damage/irritation (UN-GHS Category 1/2) from liquid chemicals not requiring such hazard classification (UN-GHS No Category). Histological examination of this ocular equivalent model, based on Normal Human Keratinocytes (NHK) cultured in a chemically defined medium, revealed a stratified and well-organized tissue construct. Moreover, barrier robustness and functionality were demonstrated by the effective time-SO (ET50) of Triton X-100 measurement. The prediction model is based on cytotoxicity assessment following a test chemical exposure. When the mean tissue viability was over 60%, the chemical was defined as No Category; otherwise, it was classified as Category 1/2. In accordance with the applicable OECD guidance document (ENV/JM/MONO (2015)23), the performance of the model for eye hazard identification was evaluated with the minimum list of reference chemicals. As a result, the method scored 84.4% Accuracy, 70.8% Specificity, 100% Sensitivity and 93.3% for Concordance, demonstrating prediction performances close to those of Validated Reference Methods that are commonly used for regulatory purposes. Finally, these results suggest that this in-house RhCE based test method is a qualitative and accurate screening tool for eye hazard identification of liquid chemicals.