Cells around the corner

TL;DR

This paper investigates the elastic properties of spindle-like cell monolayers near corners, using liquid crystal theory to understand tissue organization and determine the ratio of splay to bend elastic constants.

Contribution

It introduces a method to analyze cell monolayer deformations near corners, estimating elastic anisotropy and validating liquid crystal models for biological tissues.

Findings

The angle where splay and bend are equally likely depends on elastic constant ratio.

Liquid crystal theory accurately models cell deformation under confinement.

For fibroblast cells, splay and bend elastic constants are approximately equal.

Abstract

The study of spindle-like cells as nematic liquid crystals has led to remarkable insights in the understanding of tissue organization and morphogenesis. In the characterization of this anomalous liquid crystal material, we focus on the energetic cost of splay and bend deformations, in order to determine the elastic anisotropy of the material, i.e. the ratio of the elastic constants associated with splay and bend. We explore the behavior of monolayers of cells in proximity to corners, where cells arrange in splay or bend configuration, strongly dependent on the amplitude of the wedge angle. The angle at which splay and bend deformations are equally likely is determined by the ratio between splay and bend elastic constants. We also show that the splay and bend deformations under confinement can be well approximated using equilibrium liquid crystal theory and statistical mechanics. Finally, our data suggest that for fibroblast cells the common approximation of equal bend and splay constant is valid.