Rabbit, rat and pig corneas: main characteristics and storage in organ culture

Purpose Except for primates, animal models of corneal are far from human. Animal models of corneal storage are virtually non‐existent. Aim: to update the main characteristics (especially for endothelial cells (EC)) of the cornea of 3 easily available animals, as well as their ability to be stored in organ culture (OC) Methods 30 corneas of 6 month‐old Large White pig, 20 of 10 week‐old California rabbits and 10 of 8 week‐old Lewis rats were investigated. Macroscopic data: 1/horizontal and vertical diameters (digital calliper), 2/transparency (analysis of modulation and contrast transfer functions), 3/ corneal thickness (CT) (ultrasound pachymetry). Microscopic data: 1/ histology on Hematein‐Eosin‐Safran stained cross sections and ultrastructure, 2/ EC density (ECD) and morphometry, 3/ EC proliferative status (Ki67 and 5‐Ethynyl‐2’‐Deoxyuridine incorporation (Clik‐it EdU)), differentiation status (Na+/K+ ATPase, ZO‐1, JAM‐1), and existence of stem cells (Nestin, ABCG2, Telomerase). Fresh corneas were organ cultured in 2 commercially available media. CT was measured every 2h during 6h, then every 12h. Transparency and EC survival was determined after 2, 3 and 4 days of OC Results We constituted a complete database of ex vivo corneal characteristics of the 3 species. ECD, polymorphism and polymegathism were higher than in human. CT increased rapidly (up to 3 times) in both OC media, resulting in biconvex tissues with almost complete loss of transparency and significant endothelial folding. EC survival decreased especially in folds Conclusion Corneas of the 3 animals cannot be stored more than 2 to 3 days in OC media designed for human. Specific media should be developed to obtain reliable models of animal corneal OC