Application of the reconstructed rabbit corneal epithelium model to assess the in-vitro eye irritant test of chemicals.

The rabbit corneal epithelium model (RCE model) was developed as a three-dimensional in vitro model to replace animal testing for the assessment of eye irritation. In the model, a stratified culture of rabbit corneal epithelial cells is grown at the air-liquid interface on collagen gel that acts as a parabasal membrane. Histological cross-sections show that the structure of the RCE model closely parallels that of the rabbit corneal epithelium. The eye irritation potency of test samples is estimated from the measurement of viability using the MTT assay in conjunction with the RCE model. A set of 30 chemicals belonging to different families with known in vivo Draize score was investigated with the in vitro eye irritation test using the RCE model in order to internally validate the protocol. Use of the RCE model at concentrations of 0.05%, 0.50%, and 1.00% and the calculation of the IC50 and percentage of viability allowed the irritants to be divided into four classes. The performance of the in vitro eye irritation test at a concentration of 0.50% using the RCE model was characterized by good sensitivity (92.3%), good specificity (100%), and good accuracy (93.3%) compared with the irritation classification predicted by in vivo Draize score at concentrations of 10% and 100%. These results indicate that the RCE model may provide a useful and sensitive in vitro eye irritation test as an alternative method to the Draize test.