Inducing Integer Charge Topological Defects in Cell Monolayers

Many cells, when confined on 2-dimensional substrates, align with their neighbors and arrange as nematic liquid crystals (LCs). As in LCs, topological defects are also present in cell monolayers, and these regions of disorder impact the behavior of cells [1,2]. We induce alignment of fibroblasts (3T6) via contact guidance with boundary conditions that induce topological defects with integer topological charge on micropatterned substrates [3]. By varying the height of ridges, we change the anchoring strength which sets the direction for cell alignment and study the effect on cell alignment. We identify two different cell configurations near topological defects with azimuthal symmetry, where cells are able to change not only their alignment, but also their shape. We also vary the initial seeding concentration of cells, which changes the density of cells in their initial configuration, where at high initial density the cells can get frozen into misaligned configurations. [1] K Kawaguchi et al. Nature 545, 327 (2017) [2] TB Saw et al. Nature 544, 212 (2017) [3] K Endresen et al. arXiv: 1912.03271 [cond-mat.soft] 2019.