Modeling Collective Cell Migration: Clusters and Monolayers*

Collective migration is prevalent in nature, from migrating animals to groups of cells. At the level of the cells, motile collectives appear in the form of isolated clusters of different sizes, as well as within continuous tissues. The modeling of this phenomena will be presented, using analytic simplified models, as well as particle-based numerical simulations. We describe several examples where physical models shed light on the biological system: (i) Chemotaxis of 2D and 3D cellular clusters. By comparing the observed dynamics of cellular clusters to the theoretical models, we can extract the nature of the underlying traction forces, and the coordination between these forces. The phenomenon of spontaneous transitions between migration and rotation of these clusters is also elucidated. (ii) The collective motion at the edge of an expanding, continuous monolayer exhibits instabilities. We model this instability, which also explains the behavior of collective flows within geometric confinement.