Natural Cross-Linkers Stabilizedacellular Porcine Corneal Stroma for Lamellar Transplantation

Acellular porcine corneal stroma (APCS) is a promising alternative to human donor cornea for lamellar keratoplasty (LKP). However, the detergents, enzymes and physical forces during decellularization unavoidably alter cornea extracellular matrix composition and disrupt its ultrastructure, making it less mechanically stable and liable to degradation in vitro and in vivo. Herein, we systematically analyzed the low biomechanics and easy degradability of APCS from structure and protein composition. Then, we introduced natural cross-linkers to stabilize the APCS that exhibited color variations during cross-linking. Herein, we developed a protective cross-linking system by combining cross-linkers with bovine serum albumin (BSA) to reduce color change, maintain transparency, and improve the mechanical properties of APCS. Proanthocyanidin (PA)/BSA-cross-linked APCS showed favorable corneal transparency and swelling property; the improved overall and surface corneal biomechanics were comparable to those of human donor cornea, revealing good cytocompatibility and strong resistance to enzymatic degradation. Results from corneal micropocket implantation indicated that the PA/BSA-cross-linked APCS gets more corneal stroma cells migrated and LKP in the rabbit model showed complete re-epithelialization without graft melt, and the stitches had scarcely loosened one month after the operation. The proposed method may provide more stable cornea substitutes and be applicable in other bioengineering fields.