Fluctuating Hydrodynamics Describes Transport in Cellular Aggregates

TL;DR

This paper develops a fluctuating hydrodynamics model for cellular aggregates, revealing how microscopic activity influences transport properties and breaks Einstein relation in non-equilibrium conditions.

Contribution

It introduces a novel fluctuating hydrodynamics framework for active multicellular aggregates based on macroscopic fluctuation theory.

Findings

Transport coefficients decrease inside clusters

Breakdown of Einstein relation in non-equilibrium regimes

Model aligns with microscopic simulations

Abstract

Biological functionality of cellular aggregates is largely influenced by the activity and displacements of individual constituent cells. From a theoretical perspective this activity can be characterized by hydrodynamic transport coefficients of diffusivity and conductivity. Motivated by the clustering dynamics of bacterial microcolonies we propose a model of active multicellular aggregates and use recently developed macroscopic fluctuation theory to derive a fluctuating hydrodynamics for this model system. Both semi-analytic theory and microscopic simulations show that the hydrodynamic transport coefficients are affected by non-equilibrium microscopic parameters and significantly decrease inside of the clusters. We further find that the Einstein relation connecting the transport coefficients and fluctuations breaks down in the parameter regime where the detailed balance is not satisfied. This study offers valuable tools for experimental investigation of hydrodynamic transport in other systems of cellular aggregates such as tumor spheroids and organoids.