Energy barriers govern glassy dynamics in tissues

TL;DR

This paper develops models to understand how energy barriers influence glassy dynamics in tissues, linking cell properties to collective cell movement and behavior in biological processes.

Contribution

It introduces a theoretical framework that calculates energy barriers to cell rearrangements, revealing their distribution and impact on tissue dynamics, which was previously unclear.

Findings

Energy barriers are exponentially distributed and depend on cell neighbors.

Cell motion correlation times increase rapidly with decreasing cell activity.

Models reproduce observed caging behavior in cell trajectories.

Abstract

Recent observations demonstrate that densely packed tissues exhibit features of glassy dynamics, such as caging behavior and dynamical heterogeneities, although it has remained unclear how single-cell properties control this behavior. Here we develop numerical and theoretical models to calculate energy barriers to cell rearrangements, which help govern cell migration in cell monolayers. In contrast to work on sheared foams, we find that energy barrier heights are exponentially distributed and depend systematically on the cell's number of neighbors. Based on these results, we predict glassy two-time correlation functions for cell motion, with a timescale that increases rapidly as cell activity decreases. These correlation functions are used to construct simple random walks that reproduce the caging behavior observed for cell trajectories in experiments. This work provides a theoretical framework for predicting collective motion of cells in wound-healing, embryogenesis and cancer tumorigenesis.