Active Inter-cellular Forces in Collective Cell Motility

TL;DR

This study uses a phase-field model to investigate how polar and active inter-cellular forces influence collective cell sheet dynamics, revealing transitions between jammed, liquid, and flocking states based on force strengths and cell polarity alignment.

Contribution

It introduces a phase-field modeling approach to analyze the interplay of polar and inter-cellular forces in collective cell motility, highlighting the conditions for different dynamic states.

Findings

Transition from jammed to liquid states with increased forces

Flocking behavior occurs with strong polar forces

Inter-cellular activity disrupts flocking at high levels

Abstract

The collective behaviour of confluent cell sheets is strongly influenced both by polar forces, arising through cytoskeletal propulsion and by active inter-cellular forces, which are mediated by interactions across cell-cell junctions. We use a phase-field model to explore the interplay between these two contributions and compare the dynamics of a cell sheet when the polarity of the cells aligns to (i) their main axis of elongation, (ii) their velocity, and (iii) when the polarity direction executes a persistent random walk.In all three cases, we observe a sharp transition from a jammed state (where cell rearrangements are strongly suppressed) to a liquid state (where the cells can move freely relative to each other) when either the polar or the inter-cellular forces are increased. In addition, for case (ii) only, we observe an additional dynamical state, flocking (solid or liquid), where the majority of the cells move in the same direction. The flocking state is seen for strong polar forces, but is destroyed as the strength of the inter-cellular activity is increased.