Re-entrant dynamics in cell collectives under activity tuning

Determine whether dense cell collectives at fixed packing fraction exhibit non-intuitive dynamical behavior, including re-entrant dynamics, when activity is tuned (for example, by varying the persistence time of self-propulsion), analogous to the behavior observed in assemblies of rigid self-propelled particles.

Background

In dense assemblies of rigid self-propelled particles, tuning the activity at constant density can lead to non-intuitive dynamical phenomena such as re-entrant behavior. Whether analogous behavior occurs in living or model cell collectives has been unclear because biological systems generally lack a straightforward knob to systematically tune activity without simultaneously altering other complicating factors such as division, apoptosis, or adhesion.

The paper introduces a synthetic model system of deformable, self-propelled cell-mimics that permits controlled tuning of activity and explores collective dynamics near confluence. The authors highlight that prior to such controllable systems, it was unknown if similar re-entrant physics manifests in cell collectives when activity is varied at fixed density.