Polymer design for corneal epithelial tissue adhesion: Pore density

Abstract

A porous polymer is required to sustain corneal epithelial tissue on the anterior surface of an implantable contact lens (corneal onlay). Porosity creates topography on the polymer surface and, if defined, this can be manipulated to elicit a particular tissue response. Previous work identified pores of 100-nm diameter to be the critical size of a discontinuity in a polymer surface to facilitate the migration, stratification, and sustained adhesion of corneal epithelial tissue. Now we address the issue of pore density. Corneal epithelial tissue was grown for 21 days on nonporous polycarbonate and polycarbonate track-etched with pores 100-nm diameter with pore densities ranging from 0.27 and 14.4% of the total polymer surface area. Histology was used to score epithelial structure, and electron microscopy was used to quantitate the formation of adhesive structures (basal lamina and hemidesmosomes) at the tissue-polymer interface. Data showed that epithelial tissue stratified and epithelial adhesive structures formed on polycarbonate surfaces with pore densities between 0.52 and 14.4% inclusive. This means that epithelial tissue can be maintained on a polymer where up to 14.4% of the surface is dedicated to small discontinuities in the form of pores 100-nm diameter. These figures can be used to specify the design of a polymer for applications requiring epithelial cover.

Biological length scale topography enhances cell-substratum adhesion of human corneal epithelial cells

“…In addition, cells plated on surfaces with microscale pores were unable to form or had very few hemidesmosomes. This study and a subsequent study on the effect of pore density used sheets of epithelial cells (Evans et al, 1999b;Evans et al, 2003) and found that cell-cell signaling influences cell behavior. Our study, in contrast, was focused on individual cells.…”

“…Interestingly, while there have been a number of studies that have investigated the adhesion of sheets of cells on biologically relevant substrata (Evans et al, 1999b;Evans et al, 2003), we know of no previous studies to quantify the strength of cell-substratum adhesion of single cells…”

What We Should Know About the Cellular and Tissue Response Causing Catheter Obstruction in the Treatment of Hydrocephalus

“…Keeping in mind that contact between like cells may cause inhibition of proliferation and growth, 131 cell proliferation may decrease with small distances between holes. To the opposite extreme, however, epithelial cells have been shown to bridge across holes that are approximately 0.893 to 0.143 mm apart, 132 suggesting that contact inhibition may be slowed if the proximity of the neighboring holes is extremely small. To our knowledge, these relationships have not been studied to date to inhibit ventricular catheter obstruction.…”

Phenomenon of “contact guidance“ on the surface with nano-micro-groove-like pattern and cell physiological effects

“…Pseudopodia play an important role in sensing the stimulus of surroundings and guiding the locomotion of cells [48] . Evans et al [49] investigated the behavior of pseudopodia, and they reported that the occurrence of "contact guidance" was due to the steric hindrance caused REVIEW POLYMER PHYSICS by the "ridges" horizontally perpendicular to groove pattern filopodia and lamellipodium confronted. Teixeira et al [14] and Dalby et al [50] also reported that filopodia and lamellipodium can "sense" the stimulus of the steric hindrance horizontally perpendicular to groove-like pattern.…”