Quantifying material properties of cell monolayers by analyzing integer topological defects

TL;DR

This paper introduces a method based on liquid crystal physics to quantify the material properties of cell monolayers by analyzing the behavior of topological defects, aiding understanding of tissue mechanics during development.

Contribution

It presents a hydrodynamic approach to determine tissue material parameters from defect analysis, specifically applied to C2C12 cell monolayers in confined geometries.

Findings

Monolayers exert compressive stresses at defect centers.

Localized cell differentiation occurs at defect sites.

The method enables quantification of tissue mechanical properties.

Abstract

In developing organisms, internal cellular processes generate mechanical stresses at the tissue scale. The resulting deformations depend on the material properties of the tissue, which can exhibit long-ranged orientational order and topological defects. It remains a challenge to determine these properties on the time scales relevant for developmental processes. Here, we build on the physics of liquid crystals to determine material parameters of cell monolayers. Specifically, we use a hydrodynamic description to characterize the stationary states of compressible active polar fluids around defects. We illustrate our approach by analyzing monolayers of C2C12 cells in small circular confinements, where they form a single topological defect with integer charge. We find that such monolayers exert compressive stresses at the defect centers, where localized cell differentiation and formation of three-dimensional shapes is observed.