Biochemical and biophysical engineering of an artificial basement membrane of the corneal epithelium

The insufficient supply of donor corneal tissue motivates the engineering of artificial corneas with a high degree of biointegration and significant rates of success. However, currently available artificial corneas suffer from problems, including epithelial downgrowth, infection and stromal melting. Most of the major problems, which eventually lead to rejection, could be greatly reduced or eliminated through the improved formation and maintenance of a healthy epithelium over the implant. We hypothesize that this epithelial formation may be enhanced through the incorporation of biomimetic chemical and physical cues found on the native basement membrane of the cornea onto the surface of the keratoprosthesis.;Hydrogels synthesized from poly (ethylene glycol) diacrylate (PEGDA) were investigated as a platform to simultaneously present human corneal epithelial cells (HCECs) in vitro with topography and adhesion peptides to mimic the native physical and chemical attributes of the basement membrane underlying the epithelium in vivo. PEGDA hydrogels prevented non-specific HCEC adhesion and were functionalized with the integrin-binding peptide Arg-Gly-Asp (RGD). Hydrogels molded with ridge and groove features with lateral dimensions from 200 nm to 2000 nm and 300 nm depth retained the topography after equilibrium swelling. The alignment of HCECs cultured on topographic surfaces functionalized with RGD showed substantially less dependence on the culture media than substrates promoting non-specific attachment. This demonstrates that the moldable RGD-functionalized hydrogels allow for decoupling of the cues from surface chemistry, soluble factors, and topography that simultaneously impact HCEC behavior.;We also investigated the use of these non-fouling substrates in wound healing experiments, where we found that the rate of corneal epithelial wound healing was significantly increased by 50% in hydrogel surfaces containing topographic features, compared to flat surfaces with the same chemical characteristics. This increased healing is mainly due to the increased migration of the epithelial cells on the edge of the wound. These results show the potential benefit of restructuring and improving the surface of artificial corneas to enhance the coverage of the keratoprosthesis by epithelial cells and induce the formation of a functional epithelium.