Scaling of Traction Forces with Size of Cohesive Cell Colonies

TL;DR

This study investigates how the mechanical forces exerted by cohesive cell colonies scale with their size, revealing a transition towards surface tension behavior and proposing a model to explain force distribution.

Contribution

It introduces a quantitative analysis of traction force scaling in cell colonies and presents a simple elastic model capturing observed force distributions and scaling behaviors.

Findings

Traction stresses are localized at colony peripheries.

Total traction force scales with colony radius.

Scaling approaches linear for large colonies, indicating surface tension emergence.

Abstract

To understand how the mechanical properties of tissues emerge from interactions of multiple cells, we measure traction stresses of cohesive colonies of 1-27 cells adherent to soft substrates. We find that traction stresses are generally localized at the periphery of the colony and the total traction force scales with the colony radius. For large colony sizes, the scaling appears to approach linear, suggesting the emergence of an apparent surface tension of order 1E-3 N/m. A simple model of the cell colony as a contractile elastic medium coupled to the substrate captures the spatial distribution of traction forces and the scaling of traction forces with the colony size.