Development of a novel ex vivo equine corneal model

Objective To develop an ex vivo equine corneal organ culture model. Specifically, to assess the equine cornea's extracellular matrix and cellularity after 7 days using two different culture techniques: either (i) immersion system or (ii) air/liquid interface system, to determine the best ex vivo equine corneal model. Animals Studied Fourteen healthy equine corneas of various breeds. Procedures Equine corneas with 2 mm of perilimbal sclera were freshly harvested from 7 horses undergoing humane euthanasia. One corneal-scleral ring (CSR) from each horse was randomly placed in the (i) immersion condition organ culture system (IC), with the contralateral CSR being placed in the (ii) air/liquid interface organ culture system (ALC) for 7 days. All corneas were evaluated using serial daily gross photography, histology, qPCR, and TUNEL assay. Results corneal-scleral rings placed in the IC (i) had complete loss of corneal transparency on gross photography by 7 days, showed a significant level of corneal stromal disorganization, significantly increased alpha-SMA levels on qPCR, and apoptosis on TUNEL assay compared to controls. The ALC (ii) had weak stromal disorganization on histopathologic examination and was not significantly different from normal equine corneal controls on all other evaluated parameters. Conclusions The air-liquid interface organ culture system maintains the equine cornea's extracellular matrix and preserves corneal transparency, while the immersion condition results in near complete degradation of normal equine corneal architecture after 7 days in culture. The air-liquid organ culture is a viable option to maintain a healthy equine cornea in an ex vivo setting for wound healing studies.