Persistent adhesion of epithelial tissue is sensitive to polymer topography

The persistent adhesion of corneal epithelial tissue to the surface of a porous polymer is of interest in the development of a corneal onlay. Using an in vitro model system, this study examined the effect of polymer surface topography on the assembly of basement membrane and hemidesmosomes. Corneal epithelial tissue was grown on polycarbonate surfaces with a range of pore sizes (0.1-3.0 micron, pore diameter) and an equivalent nonporous surface. The ultrastructure of the tissue-polymer interface was evaluated using electron microscopy. On the porous surfaces, the tissue responded to a balance between the size of the discontinuity (pores) and the amount of polymer surface between the pores. Continuous basement membrane and a regular pattern of hemidesmosomal plaque occurred only on the 0.1 micron surface, where both the pores and the total surface area covered by pores were relatively small. The assembly of adhesive structures on surfaces with pore diameters between 0.4-2.0 microns was restricted to regions of polymer between pores. No adhesive structures assembled on the nonporous or on the 3.0-micron surface. These results demonstrate that, in addition to porosity, surface topography is a significant factor in the formation of structures involved in the persistent adhesion of stratified epithelial tissue on a polymer.