Cytoskeleton remodelling of confluent epithelial cells cultured on porous substrates

Abstract

The impact of substrate topographyon themorphological andmechanical properties of confluentMDCK-II cells cultured on porous substrateswas scrutinized by means of various imaging techniques as well as atomic force microscopy comprising force volume and microrheology measurements. Regardless of the pore size, ranging from 450 to 5500 nm in diameter, cells were able to span the pores. They did not crawl into the holes or growaround the pores. Generally, we found that cells cultured on non-porous surfaces are stiffer, i.e. cortical tension rises from 0.1 to 0.3 mN m21, and less fluid than cells grown over pores. The mechanical data are corroborated by electronmicroscopy imaging showing more cytoskeletal filaments on flat samples in comparison to porous ones. By contrast, cellular compliance increases with pore size and cells display a more fluid-like behaviour on larger pores. Interestingly, cells on pores larger than 3500 nm produce thick actin bundles that bridge the pores and thereby strengthen the contact zone of the cells.