Nematic order by elastic interactions and cellular rigidity sensing

TL;DR

This paper models how elastic interactions among active force generators in cells can lead to nematic order, revealing how cellular rigidity sensing depends on matrix elasticity with distinct regimes.

Contribution

It introduces a minimal model predicting nematic order from elastic interactions, linking cell shape, matrix elasticity, and stress fiber alignment.

Findings

Nematic order arises spontaneously from elastic interactions.

Cellular rigidity sensing shows two regimes: step-like and optimal rigidity dependence.

Order depends on cell density and matrix elasticity.

Abstract

We predict spontaneous nematic order in an ensemble of active force generators with elastic interactions as a minimal model for early nematic alignment of short stress fibers in non-motile, adhered cells. Mean-field theory is formally equivalent to Maier-Saupe theory for a nematic liquid. However, the elastic interactions are long-ranged (and thus depend on cell shape and matrix elasticity) and originate in cell activity. Depending on the density of force generators, we find two regimes of cellular rigidity sensing for which orientational, nematic order of stress fibers depends on matrix rigidity either in a step-like manner or with a maximum at an optimal rigidity.