The role of the nucleus for cell mechanics: an elastic phase field approach

TL;DR

This paper introduces an elastic phase field computational method to model the mechanical role of the nucleus in cell dynamics, revealing how the nucleus influences cell stiffness and stress distribution in various environments.

Contribution

The study presents a novel elastic phase field approach to simulate cell mechanics with a stiff nucleus, enabling analysis of its effects in different physical scenarios.

Findings

Nuclear stress is shielded by adhesive patterns.

Effective cell-nucleus modulus can be extracted from force curves.

Nucleus has a weaker effect in micropipette aspiration experiments.

Abstract

The nucleus of eukaryotic cells typically makes up around 30% of the cell volume and has significantly different mechanics, which can make it effectively up to ten times stiffer than the surrounding cytoplasm. Therefore it is an important element for cell mechanics, but a quantitative understanding of its mechanical role during whole cell dynamics is largely missing. Here we demonstrate that elastic phase fields can be used to describe dynamical cell processes in adhesive or confining environments in which the nucleus acts as a stiff inclusion. We first introduce and verify our computational method and then study several applications of large relevance. For cells on adhesive patterns, we find that nuclear stress is shielded by the adhesive pattern. For cell compression between two parallel plates, we obtain force-compression curves that allow us to extract an effective modulus for the cell-nucleus composite. For micropipette aspiration, the effect of the nucleus on the effective modulus is found to be much weaker, highlighting the complicated interplay between extracellular geometry and cell mechanics that is captured by our approach. We also show that our phase field approach can be used to investigate the effects of viscoelasticity and cortical tension.