Design concept and construction of a hybrid lamellar keratoprosthesis

A novel hybrid lamellar keratoprosthesis composed of epithelium and stroma was developed. Artificial extracellular matrices were constituted of photocrosslinkable copolymers of N,N-dimethylacrylamide and 2-(7-coumaroxy)ethyl methacrylate; a copolymer with a high content of coumarin (A) was used as a basement membrane (BM) for the epithelium, and a copolymer with a low content (B) was used for entrapment of keratocytes. The lamellar keratoprosthesis was constructed as follows: First, a viscous buffer solution containing water-soluble copolymer (B), collagen, and keratocytes derived from rabbit was prepared. Then, a cast film of copolymer (A) was tightly placed onto the mixed solution. Ultraviolet light irradiation leading to intermolecular dimerization of coumarin groups resulted in the formation of a transparent keratocyte-entrapped hydrogel that was layered with an artificial BM. Epithelial cells were seeded on the BM. Further culturing produced the lamellar keratoprosthesis, within which both kinds of cells proliferated well. The preliminary study on two week implantation of the lamellar keratoprosthesis in rabbits provided quite promising results; adverse tissue reactions, such as corneal opacity and neovascularization, were not observed.