Substrate disorder promotes cell motility in confluent tissues

TL;DR

This study shows that substrate heterogeneity at small scales enhances cell motility in confluent tissues, contrasting with effects of cellular heterogeneity, and links tissue rigidity to the spatial distribution of rigid cells.

Contribution

It introduces a model linking substrate disorder to tissue mechanics and cell motility, revealing how small-scale heterogeneity reduces tissue rigidity and promotes movement.

Findings

Smaller preferred geometry length scale increases cell motility.

Tissue becomes less rigid with substrate heterogeneity.

Rigidity transition involves formation of a spanning cluster of rigid cells.

Abstract

In vivo and in vitro cells rely on the support of an underlying biocompatible substrate, such as the extracellular matrix or a culture substrate, to spread and proliferate. The mechanical and chemical properties of such structures play a central role in the dynamical and statistical properties of the tissue. At the cell scale, these substrates are highly disordered. Here, we investigate how spatial heterogeneities of the cell-substrate interaction influence the motility of the cells in a model confluent tissue. We use the Self-Propelled Voronoi model and describe the disorder as a spatially dependent preferred geometry of the individual cells. We found that when the characteristic length scale of the preferred geometry is smaller than the cell size, the tissue is less rigid than its homogeneous counterpart, with a consequent increase in cell motility. This result is in sharp contrast to what has been reported for tissues with heterogeneity in the mechanical properties of the individual cells, where the disorder favors rigidity. Using the fraction of rigid cells, we observe a collapse of the motility data for different model parameters and provide evidence that the rigidity transition in the model tissue is accompanied by the emergence of a spanning cluster of rigid cells.