Construction of a collagen-based, split-thickness cornea substitute

Tissue-engineered corneas may become a promising alternative to allografts in the treatment of serious cornea defects because of the tunable characteristics of the biomaterials, biomimetic designs, and incorporation of patient's own cells. In this study, collagen foam was coated with a fibrous mat to mimic the stromal layer and the Bowman's layer. The stromal layer substitute was made of N-ethyl-N-(3-dimethyl aminopropyl)carbodiimide/N-hydroxysuccinimide-cross-linked collagen-chondroitin sulfate foam and seeded with primary human corneal keratocytes (HK). Retinal pigment epithelium (RPE) cells served as the epithelial layer after seeding on a dehydrothermally cross-linked collagen type I fibrous mat deposited directly on top of the foams by electrospinning. The physical characterization and the in vitro studies showed that the designed cornea replacement was suitable for cell attachment and growth, and co-culture of the two cell types induced more extracellular matrix (ECM) deposition than the single cell-seeded constructs. The fiber layer was shown to be successful in separating the HK and RPE cells, and still allowed them to maintain cell-cell communication as the increase in ECM deposition and the maintenance of the high transparency (~80%) suggested. This split-thickness corneal substitute was also shown to be readily suturable without any major tears at the end of a short co-culture of 30 days.