Review: How dynamic prestress governs the shape of living systems, from the subcellular to tissue scale

TL;DR

This review explores how internal stresses, or prestress, generated by molecular activities influence shape changes in cells and tissues across scales, highlighting theoretical tools and categorizing different prestress distributions.

Contribution

It introduces the concept of topological prestress and provides a unified framework for understanding prestress-driven shape changes in living systems.

Findings

Prestress can be categorized as heterogeneous, anisotropic, or differential.

Active processes can induce topological prestress by altering tissue microstructure.

Theoretical tools help conceptualize the mechanics of living systems across scales.

Abstract

Cells and tissues change shape both to carry out their function and during pathology. In most cases, these deformations are driven from within the systems themselves. This is permitted by a range of molecular actors, such as active crosslinkers and ion pumps, whose activity is biologically controlled in space and time. The resulting stresses are propagated within complex and dynamical architectures like networks or cell aggregates. From a mechanical point of view, these effects can be seen as the generation of prestress or prestrain, resulting from either a contractile or growth activity. In this review, we present this concept of prestress and the theoretical tools available to conceptualise the statics and dynamics of living systems. We then describe a range of phenomena where prestress controls shape changes in biopolymer networks (especially the actomyosin cytoskeleton and fibrous tissues) and cellularised tissues. Despite the diversity of scale and organisation, we demonstrate that these phenomena stem from a limited number of spatial distributions of prestress, which can be categorised as heterogeneous, anisotropic or differential. We suggest that in addition to growth and contraction, a third type of prestress -- topological prestress -- can result from active processes altering the microstructure of tissue.