Collective contact guidance triggers polar laning of turbulent epithelial monolayers*

Collective cell flows within tissues are central in biological processes such as morphogenesis, wound healing, or cancer progression. In vivo, cell migration is often influenced by oriented structures in the local environment, such as bundles of extra cellular matrix, that can be mimicked in vitro by topographical structures such as grooves and ridges. Although the ”contact guidance” of individual cells on such textured substrates has been thoroughly studied, little is known on the cell collective response to these cues.

Here, we show that, when plated on subcellular grooves, a confluent monolayer of human bronchial epithelial cells spontaneously organizes into supracellular alternating millimeter-long polar lanes that migrate in antiparallel directions. These lanes coarsen with time reaching widths of several hundred micrometers.

Our results are well captured by a hydrodynamic description of an active polar fluid that undergoes a disorder-to-flocking transition mediated by the damping of transverse fluctuations caused by the substrate anisotropic friction. Complementary particle-based simulations identify polarity-velocity coupling as a key ingredient in this new laning transition.