Human Corneal Cellular Response to the Synthetic Stromal Matrix Replacements

Abstract

Abstract: : Purpose: Polyurethane-based biomaterials have been used as heart valves. Our aim is to determine the feasibility of using such materials as potential corneal stromal replacements. Material and Methods: Composite collagen-bound polyurethane corneal stromas of 3 different formulations were moulded into corneal stromas with different degrees of rigidity vs flexibility. These were classified as 1) very flexible (but also soft) 2) very rigid; 3) a combination of flexible with some rigidity. These polymers were sutured onto human donor rims and then organ cultured. Cell migration from the human corneal rims into the matrix was examined. Results: Within 3-5 days, half the polymer surface was covered by epithelial cells that have migrated from the human corneal rims. After air-lifting the cultures at day 5, the epithelial cells stratified but did not cover entire surface. Morphology of these epithelial cells was comparable to those of control intact human donor corneas. Stromal cells migrated into corneas that were soft but not the two more rigid ones. Endothelial cells from corneas of younger donor (under 50 years of age) migrated onto the polymer surface after 5 days, covering up to half of the cornea after 2 weeks. The migrated endothelial cells retained a monolayer configuration but underwent morphological changes. Irregular cell sizes and blebs were observed. Conclusion: Polyurethane-based materials showed some biocompatibility. However, surface modification is most likely required to optimize cell migration and survival on and within these matrices. The in-growth of stromal cells occurred only in the softer matrices, correlating with previous reports from keratoprosthesis studies that the packing and pore sizes of the materials are important for anchorage into host tissues. A strategy for dealing with endothelial cells, either preventing their migration onto the polymer or replacement with donor cells will need to be determined.

Keywords: cornea: basic science • cornea: endothelium • cornea: epithelium