Content area
Abstract
The surgical procedure known as "epikeratophakia" utilizes donor corneal tissue to reshape the anterior corneal curvature and provide permanent optical correction. While the epikeratophakia procedure has been relatively successful the development of synthetic materials for this application may serve to eliminate the need for donor tissue and improve the optical predictability of the procedure. However, before designing such materials an understanding of the cellular requirements for a synthetic corneal graft is necessary.
In this research an in vitro cell culture assay was designed to model epithelial cell outgrowth from corneal buttons onto synthetic materials. The parameters studied were the surface chemistry and hydrophobicity of the synthetic materials, the adsorption of fibronectin and albumin, the binding strength of adsorbed fibronectin, the detectability of the cell binding domain of adsorbed fibronectin, and the susceptibility of adsorbed fibronectin to proteolytic digestion.
The cell outgrowth assay was shown to be a sensitive method for comparing various materials with various pre-treatments. In general, surfaces of intermediate hydrophobicity supported the largest cell outgrowth areas. Pre-adsorption with fibronectin enhanced cell outgrowth and pre-adsorption with albumin inhibited cell outgrowth on all of the materials tested. The amount of fibronectin bound from pure solutions was found to increase with surface hydrophobicity, while fibronectin binding strength decreased as a function of surface hydrophobicity. The detectability of cell binding domain of adsorbed fibronectin did not correlate well with surface hydrophobicity or cell outgrowth. Finally, plasmin was shown to degrade adsorbed fibronectin in a substrate dependent fashion. Fibronectin adsorbed to hydrophobic substrates was most susceptible to proteolytic digestion.
The results suggested that best materials for supporting corneal epithelial cell outgrowth were those of intermediate hydrophobicity. While these materials adsorbed the lowest levels of fibronectin overall, the fibronectin which did adsorb had the highest overall biological activity and demonstrated the greatest resistance to proteolytic digestion.
