What do cells regulate in soft tissues on short time scales?

TL;DR

This study investigates how cells in soft tissues regulate their mechanical interactions, revealing that on short time scales they primarily control the contractile forces exerted on the extracellular matrix, not the ECM stress or cell shape.

Contribution

The paper combines experiments, theory, and modeling to show that cells regulate contractile forces rather than ECM stress or shape during short-term mechanical homeostasis.

Findings

Cells regulate contractile forces on short time scales.

ECM stress and cell shape remain largely unchanged during this regulation.

The integrated approach clarifies the micromechanical regulation mechanisms.

Abstract

Cells within living soft biological tissues seem to promote the maintenance of a mechanical state within a defined range near a so-called set-point. This mechanobiological process is often referred to as mechanical homeostasis. During this process, cells intimately interact with the fibers of the surrounding extracellular matrix (ECM). It remains poorly understood, however, what individual cells actually regulate during these interactions, and how these micromechanical regulations are translated to tissue level to lead to what we macroscopically call mechanical homeostasis. Herein, we examine this question by a combination of experiments, theoretical analysis and computational modeling. We demonstrate that on short time scales (hours) - during which deposition and degradation of ECM fibers can largely be neglected - cells appear to regulate neither the stress / strain in the ECM nor their own shape, but rather only the contractile forces that they exert on the surrounding ECM.