Tools for micropatterning epithelial cells into microcolonies on transwell filter substrates

Despite the importance of epithelial tissue in most major organs there have been limited attempts to tissue engineer artificial epithelium. A key feature of mature epithelium is the presence of an apical-basal polarization, which develops over 7–20 days in culture. Currently, the most widely used 2D system to generate polarized epithelium in vitro involves the filter insert culture system, however this system is expensive, laborious and requires large numbers of cells per sample. We have developed a set of micropatterning techniques to spatially control the organization of epithelial cells into microsheets on filter inserts under the culture conditions necessary to induce epithelial cell polarization. Micropatterning improves cell uniformity within each microsheet, allows multiple sheet analysis on one filter insert, and reduced cell number requirements. We describe an agarose patterning method that allows maintenance of cell patterns for over 15 days, the time necessary to induce apical-basal polarization. We also describe a Parafilm™ patterning method that allows patterning for 5 to 15 days depending on cell type and only allows the generation of stripes and circular microsheets. The parafilm™ method however is extremely straightforward and could be easily adopted by any laboratory without the need of access to specialized microfabrication equipment. We also demonstrate that micropatterning epithelial cells does not alter the localization of the apical-basal marker ZO-1 or the formation of cilia, a marker of epithelium maturation. Our methods provide a novel tool for studying epithelial biology in polarized epithelium microsheets of controlled size.