Biopolymers: life's mechanical scaffolds

TL;DR

This paper reviews recent experimental and theoretical advances in understanding how the structural and dynamic properties of biopolymer scaffolds like the cytoskeleton and extracellular matrix enable cells and tissues to withstand loads, adapt, and heal.

Contribution

It highlights new insights into the physical mechanisms behind the resilience, adaptability, and self-healing of biological tissues based on their complex polymer structures.

Findings

Porous structure and hierarchy confer mechanical resilience.

Transient crosslinking enables adaptability and self-healing.

Mechanochemical activity contributes to tissue robustness.

Abstract

The cells and tissues that make up our body juggle contradictory mechanical demands. It is crucial for their survival to be able to withstand large mechanical loads, but it is equally crucial for them to produce forces and actively change shape during biological processes such as tissue growth and repair. The mechanics of cell and tissues is determined by scaffolds of protein polymers known as the cytoskeleton and the extracellular matrix, respectively. Experiments on model systems reconstituted from purified components combined with polymer physics concepts have already successfully uncovered some of the mechanisms that underlie the paradoxical mechanics of living matter. Initial work focussed on explaining universal features such as the nonlinear elasticity of cells and tissues in terms of polymer network models. However, living matter exhibits many advanced mechanical functionalities that are not captured by these coarse-grained theories. In this Review, we focus on recent experimental and theoretical insights revealing how their porous structure, structural hierarchy, transient crosslinking, and mechanochemical activity confer resilience combined with the ability to adapt and self-heal. These physical insights improve our understanding of cell and tissue biology and also provide a source of inspiration for synthetic life-like materials.