Free Growth under Tension

TL;DR

This paper demonstrates that tensile stress in growing cell colonies can arise purely from tissue mechanics without the need for cellular motility forces, challenging previous explanations.

Contribution

It introduces a mechanical model of tissue growth that explains tension without motility, supported by simulations and analytical methods.

Findings

Tension can originate from tissue mechanics alone.

Colonies can expand under high tension without motility.

New analytical tools for identifying underlying mechanics.

Abstract

Ever since the ground breaking work of Trepat et al. in 2009, we know that cell colonies growing on a substrate can be under tensile mechanical stress. The origin of tension has so far been attributed to cellular motility forces being oriented outward of the colony. Works in the field mainly revolve around how this orientation of the forces can be explained, ranging from velocity alignment, self-sorting due to self-propulsion, to kenotaxis. In this work, we demonstrate that tension in growing colonies can also be explained without cellular motility forces! Using a combination of well established tissue growth simulation technique and analytical modelling, we show how tension can arise as a consequence of simple mechanics of growing tissues. Combining these models with a minimalistic motility model shows how colonies can expand while under even larger tension. Furthermore, our results and analytical models provide novel analysis procedures to identify the underlying mechanics.