Glassy dynamics in active epithelia emerge from an interplay of mechanochemical feedback and crowding

TL;DR

This study reveals that glassy dynamics in epithelial tissues result from a combination of crowding and mechanochemical feedback loops, which together enable glass-like behavior and collective oscillations in active cell layers.

Contribution

It demonstrates that mechanochemical feedback is essential for glassy dynamics in epithelial tissues, challenging previous theories that focused solely on crowding effects.

Findings

Crowding alone does not produce glassy dynamics.

Mechanochemical feedback drives glass transition in dense tissues.

Novel collective oscillations emerge from feedback interactions.

Abstract

Glassy dynamics in active biological cells remain a subject of debate, as cellular activity rarely slows enough for true glassy features to emerge. In this study, we address this paradox of glassy dynamics in epithelial cells by integrating experimental observations with an active vertex model. We demonstrate that while crowding is essential, it is not sufficient for glassy dynamics to emerge. A mechanochemical feedback loop (MCFL), mediated by cell shape changes through the contractile actomyosin network, is required to drive glass transition in dense epithelial tissues, as revealed via a crosstalk between actin-based cell clustering and dynamic heterogeneity in experiments. Incorporating MCFL into the vertex model reveals contrasting results from those previously predicted by theories -- we show that the MCFL can counteract cell division-induced fluidisation and enable glassy dynamics to emerge through active cell-to-cell communication. Furthermore, our analysis reveals, for the first time, the existence of novel collective mechanochemical oscillations that arise from the crosstalk of two MCFLs. Together, we demonstrate that an interplay between crowding and active mechanochemical feedback enables the emergence of glass-like traits and collective biochemical oscillations in epithelial tissues with active cell-cell contacts.