# Fluid pumping and active flexoelectricity can promote lumen nucleation in cell assemblies

## TL;DR

This paper explores how fluid pumping and active flexoelectricity influence lumen nucleation in cell assemblies, highlighting the coupling of mechanical, electrical, and hydraulic factors in tissue development.

## Contribution

It introduces a continuum two-fluid model incorporating fluid pumping and active electric effects to explain lumen formation in tissues.

## Key findings

- Fluid pumping promotes lumen nucleation.
- Flexoelectricity significantly influences lumen stability.
- Multiple long-term tissue states are possible.

## Abstract

We discuss the physical mechanisms that promote or suppress the nucleation of a fluid-filled lumen inside a cell assembly or a tissue. We discuss lumen formation in a continuum theory of tissue material properties in which the tissue is described as a two-fluid system to account for its permeation by the interstitial fluid, and we include fluid pumping as well as active electric effects. Considering a spherical geometry and a polarized tissue, our work shows that fluid pumping and tissue flexoelectricity play a crucial role in lumen formation. We furthermore explore the large variety of long-time states that are accessible for the cell aggregate and its lumen. Our work reveals a role of the coupling of mechanical, electrical and hydraulic phenomena in tissue lumen formation.