Cytoskeleton remodelling of confluent epithelial cells cultured on porous substrates

Abstract

The impact of substrate topography on the morphological and mechanical properties of confluent MDCK-II cells cultured on porous substrates was 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 grow around 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 m 21, and less fluid than cells grown over pores. The mechanical data are corroborated by electron microscopy 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.

PeakForce Tapping resolves individual microvilli on living cells

“…Scanning an 8 × 8 μm area indicated in Figure 2A revealed microvilli with lengths of 0.8-1 μm and diameter of 80-100 nm laying across the cell surface ( Figure 2B). Even though the appearance of microvilli on life cells is not clear, an upright, brush-like spatial configuration is likely, and fixing the cells destroys this native structure (Rother et al, 2015). Live MDCK C11 cells are shown in Figure 3 in which a 100 × 100 μm area of the monolayer was imaged with a peak force of 200 pN showing no disturbances by cantilever-cell contacts even though height differences of more than 10 μm are present ( Figure 3A).…”

Elastic properties of epithelial cells probed by atomic force microscopy

“…Thereby, Rother et al studied the morphological and viscoelastic properties of confluent MDCK-II cells grown to confluence on porous substrates with defined pore size [65]. Essentially, it was found that cells grown on large pores in the micrometer range appear softer and behave more liquid-like.…”

Microtopographies control the development of basal protrusions in epithelial sheets

“…In agreement, conserved apicobasal polarization and tight junction formation were reported for MDCK on porous substrates with similar sizes. 43 Inside hexagons, cells formed long, actin-rich protrusions in D7H5 structures, covering the whole microstructures by extending down to the glass bottom from 1 day after seeding, as visualized by F-actin staining Table 1 in the supplementary material 50 ]. Most of the results described in Secs.…”

“…48 A work on MDCK cells on porous materials, with holes between 0.45 and 5.5 μm, showed that cells grown over pores were less stiff and more fluid than cells on nonporous substrates; however, no deep protrusions seemed to be formed, which may be due to pore depth or substrate. 43 In larger pores of 50-500 μm width, cells generated protrusions of various thickness to sense their environments, in particular, protrusions horizontally bridging wells. 30…”