Xenocorneal transplantation

Abstract

Purpose of review: Donor shortage in corneal transplantation is a significant problem in Asian countries and is an emerging issue worldwide. This review will discuss current knowledge of the pathogenesis of the rejection mechanism, recent advances in xenocorneal transplantation, and feasibility of porcine xenocorneal graft.

Recent findings: α-Gal epitopes which are expressed on the porcine cornea, however less than in other vascularized organs. A small animal model provided evidence of complement-mediated or antibody-mediated rejection in porcine xenocorneal transplantation. Recent progress in genetic engineering of the pig or biomedical engineering for removal of the α-Gal epitope appears to have resulted in reduction of antibody-mediated rejection. Porcine corneal xenograft is not rejected hyperacutely in all animal models. T cells predominantly mediate xenocorneal rejection through various animal models. Survival of lamellar fresh porcine grafts is longer than that of full-thickness fresh porcine grafts. Decellularized porcine grafts also demonstrate significantly longer survival than fresh grafts do.

Summary: Recent studies have documented the potential of the porcine corneal graft as a substitute for use in human allograft and have highlighted the mechanisms of rejection of xenocorneal transplantation. Antibody-mediated or complement-mediated xenogeneic rejection should be further explored in a large animal model.