Migration and division of 3T6 cells near topological defects with integer charge*

In this work, we investigate the effects of topological defects in cell monolayers (3T6) with nematic order. We characterize the alignment, density, and dynamics of the cells near azimuthal +1 defects and hyperbolic -1 defects induced by micropatterned ridges. We observe increased density near +1 topological defects, while near -1 defects we observe a decreased density. This behavior depends on other parameters such as ridge height and cell density. For example, lower ridges result in a later onset of the nematic order and less density variation associated with the defects. We hypothesize that the mechanism for this behavior is different from that observed in other cell types, namely that it depends strongly on the cells' division rate. To test alternative hypotheses suggested by simulations, we perform immunostaining experiments of the proliferation marker Ki-67 and analyze cell dynamics.