Homeostatic Fluctuations of a Tissue Surface

TL;DR

This paper analyzes the surface fluctuations of tissues in a homeostatic state, revealing their relation to fluid and membrane spectra and establishing a generalized fluctuation-response relation despite out-of-equilibrium processes.

Contribution

It introduces a theoretical framework for understanding tissue surface fluctuations, connecting biological processes to physical fluctuation spectra and response relations.

Findings

Surface fluctuations can be mapped onto fluid and membrane spectra.

A generalized fluctuation-response relation holds despite out-of-equilibrium cell processes.

The work provides a foundation for studying tissue surface dynamics and responses.

Abstract

We study the surface fluctuations of a tissue with a dynamics dictated by cell-rearrangement, cell-division, and cell-death processes. Surface fluctuations are calculated in the homeostatic state, where cell division and cell death equilibrate on average. The obtained fluctuation spectrum can be mapped onto several other spectra such as those characterizing incompressible fluids, compressible Maxwell elastomers, or permeable membranes in appropriate asymptotic regimes. Since cell division and cell death are out-of-equilibrium processes, detailed balance is broken, but a generalized fluctuation-response relation is satisfied in terms of appropriate observables. Our work is a first step toward the description of the out-of-equilibrium fluctuations of the surface of a thick epithelium and its dynamical response to external perturbations.