Fluid-Solid Pattern Formation and Strain Localisation via Shear Banding Instability in Model Biological Tissues

TL;DR

This paper demonstrates that mechanical instabilities in tissue strain fields can lead to pattern formation and shear banding in biological tissues, offering a new perspective beyond chemical morphogen-based mechanisms.

Contribution

It introduces a mechanical instability mechanism in the vertex model that causes fluid-solid patterning and shear band formation in tissues, expanding understanding of morphogenesis.

Findings

Mechanical instability causes fluid-solid patterning.

Shear bands localize strain in tissues.

Pattern type depends on dissipation mechanisms.

Abstract

The rheological properties of biological tissues are core to processes such as cancer metastasis, wound healing and embryo development. The emergence of tissue and organ structures during morphogenesis requires the precise formation of spatial patterns. Dating back to Turing, pattern formation has been suggested to arise in tissues via spontaneous symmetry breaking instabilities in the concentration field of chemical morphogens. Within the vertex model of tissue mechanics, we show that spontaneous symmetry breaking may also arise via a mechanical instability in the strain field of a deformed tissue, leading to a patterned coexistence of fluid and solid regions, with a strong localisation of the strain into shear bands. The nature of the bands differs between tissues in which internal cell-cell dissipation dominates external drag against a substrate, and vice versa.