Surface-Modifying a Hydrogel Designed for Artificial Cornea With Extracellular Matrix Proteins to Promote Epithelialization

Abstract

Purpose: : An interpenetrating network hydrogel of poly(ethylene glycol) and poly(acrylic acid) (PEG/PAA) has been designed to serve as an artificial cornea. This study examined the capacity of the hydrogel to bind native-form proteins that promote corneal epithelialization. We used the crosslinking agents N-(3-dimethylaminopropyl)-N’-ethylcarbodiimide hydrochloride (EDC) and N-hydroxysulfosuccinimide (NHS) to covalently tether extracellular matrix proteins onto the hydrogel surface.

Methods: : PEG/PAA hydrogel surfaces were treated with EDC/NHS solution in phosphate buffer pH 6.0 for one hour, followed by incubation in extracellular matrix protein solutions of collagen type I, fibronectin, and laminin. For visualization of surface-bound proteins, the hydrogel was incubated in collagen type I-FITC. The collagen content on the hydrogel surface was quantified using a conformation-specific antibody in an enzyme-linked immunosorbent assay (ELISA). Rabbit corneal epithelial cells and fibroblasts were cultured on the surface-treated hydrogel.

Results: : Reactivity to conformation-specific collagen type I antibody demonstrated that proteins tethered using EDC/NHS onto PEG/PAA hydrogel did not denature. The amount of protein bound could also be controlled by the concentration of the crosslinking agents and coating solutions used. Collagen-FITC confirmed that the tethered protein remained bound over weeks. Epithelial cells and fibroblasts were both shown to adhere to and proliferate on the hydrogel.

Keywords: keratoprostheses