Signatures of Jamming in the Cellular Potts Model

We explore the jamming transition in the Cellular Potts Model (CPM) as a function of confinement, cell adhesion, and cell shape. To accurately characterize jamming, we compare Potts simulations of unconfined single cells, cellular aggregates, and confluent monolayers as a function of cell adhesion energies and target cell shape. We consider metrics that may identify signatures of the jamming transition, including diffusion coefficients, anomalous diffusion exponents, cell shape, cell-cell rearrangements, and velocity correlations. We find that the onset of jamming coincides with an abrupt drop in cell mobility, rapid transition to sub-diffusive behavior, and cessation of rearrangements between neighboring cells that is unique to confluent monolayers. Velocity correlations reveal collective migration as a natural consequence of high energy barriers to neighbor rearrangements for certain cell types. Cell shapes across the jamming transition in the Potts model are found to be generally consistent with predictions of vertex-type simulations and trends from experiment. Finally, we demonstrate that changes in cell shape can fluidize cellular monolayers at cellular interaction energies where jamming otherwise occurs.