The architecture of a collagen coating on a synthetic polymer influences epithelial adhesion

The current study sought to identify a collagen coating methodology for app lication to polymer surfaces that would provide for the development of adhe sive structures responsible for the sustained adhesion of corneal epithelia l tissue. We compared an uncoated microporous polycarbonate surface and equ ivalent surfaces coated with either covalently immobilized collagen 1 or ch emically crosslinked collagen 1 gel in a corneal explant outgrowth assay ov er 21 days. Electron microscopy was used to examine the formation of hemide smosomes, basal lamina, and anchoring fibrils at the tissue-polymer interfa ce. The crosslinked collagen gel preparation supported the overlying epithe lial tissue across the pore openings and allowed for the formation of ident ifiable basal lamina, hemidesmosomes, and anchoring fibrils between the epi thelial tissue and the polymer surface. Hemidesmosomal plaque, but no basal lamina or anchoring fibril formation, occurred on the uncoated surface or on that coated with covalently immobilized collagen 1. We propose that the collagen matrix provided by the crosslinked collagen gel was reorganized by the epithelial tissue and that this, combined with the secretion of ECM mo lecules, served to limit the diffusion of basement membrane components, whi ch permitted an increase in the local concentration of these molecules, whi ch favored the assembly of epithelial adhesive structures. (C) 2001 John Wi ley & Sons, Inc.