Soft yet sharp interfaces in a vertex model of confluent tissue

TL;DR

This paper investigates how biological tissues can maintain sharp boundaries despite being densely packed, revealing that cell regulation and interaction rules can produce interfaces that are mechanically soft yet sharply defined.

Contribution

It introduces a vertex model demonstrating that tissue interfaces can be both soft in mechanics and sharp in appearance due to cell regulation and neighbor interactions.

Findings

Mechanical and fluctuation-based surface tension measurements differ.

Interfaces can be mechanically soft but still sharply defined.

Cell regulation allows for unusual interface properties.

Abstract

How can dense biological tissue maintain sharp boundaries between coexisting cell populations? We explore this question within a simple vertex model for cells, focusing on the role of topology and tissue surface tension. We show that the ability of cells to independently regulate adhesivity and tension, together with neighbor-based interaction rules, lets them support strikingly unusual interfaces. In particular, we show that mechanical- and fluctuation-based measurements of the effective surface tension of a cellular aggregate yield different results, leading to mechanically soft interfaces that are nevertheless extremely sharp.