Development of endothelial cells on pillar-covered silicon



Bovine aortic endothelial cells were grown on nanostructured substrates consisting of pillars with height 10 μm, pitch 6 μm, and tip diameter 0.15 μm. Cells cultured on a pillar-covered substrate were more successful than those cultured on flat silicon wafers; however, they developed more slowly than cells cultured on glass coverslips. Specifically, focal contact maturation and matrix fibrillogenesis were inhibited. In subconfluent layers, pillars are found to penetrate deeply into both the cell cytoplasm and nucleus, suggesting that cells relaxed mechanically around the 3D topography. In confluent monolayers, actin stress fiber and VE-cadherin distributions were indistinguishable from those in confluent monolayers on coverslips. The pillars were no longer detectable because the cells have pulled themselves up such that in the confluent layer they rest atop the pillars. Inhibition of myosin IIA with blebbistatin caused cells in a confluent layer to relax around the pillars. Thus, myosin-mediated internal tension was required for monolayer stabilization above the pillars, suggesting that active tension among adjacent endothelial cells in a monolayer dominates mechanotransmission. Time (duration of culturing) rather than cell density appears to be a critical variable that allows for the transition from a subconfluent to a confluent layer. (© 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)