Gradients in solid surface tension drive Marangoni-like motions in cell aggregates

TL;DR

This study demonstrates that gradients in active surface tension within cell aggregates can induce rapid, Marangoni-like flows, influencing tissue shape and dynamics through active stress mechanisms.

Contribution

The paper reveals how active stresses generate surface tension gradients that drive large-scale flows in cell aggregates, a novel insight into tissue mechanics.

Findings

Gradients in surface tension cause rapid toroidal motions.

Surface tension gradients are proportional to surface strain.

Active stress influences surface tension and aggregate volume dependence.

Abstract

The surface tension of living cells and tissues originates from the generation of nonequilibrium active stresses within the cell cytoskeleton. Here, using laser ablation, we generate gradients in the surface tension of cellular aggregates as models of simple tissues. These gradients of active surface stress drive large-scale and rapid toroidal motion. Subsequently, the motions spontaneously reverse as stresses reaccumulate and cells return to their original positions. Both forward and reverse motions resemble Marangoni flows in viscous fluids. However, the motions are faster than the timescales of viscoelastic relaxation, and the surface tension gradient is proportional to mechanical strain at the surface. Further, due to active stress, both the surface tension gradient and surface strain are dependent upon the volume of the aggregate. These results indicate that surface tension can induce rapid and highly correlated elastic deformations in the maintenance of tissue shape and configuration.