Homogenization Theory of Ion Transportation in Multicellular Tissue

TL;DR

This paper develops a homogenization-based macro-scale model for ion transport in multicellular tissues, accounting for tissue microstructure, membrane properties, and intracellular connectivity, to better understand biological ion dynamics.

Contribution

It introduces a multiscale homogenization framework for ion transport modeling in tissues with nonlinear membrane interfaces, considering intracellular connectivity variations.

Findings

Derivation of bidomain PDE system for connected intracellular spaces.

Simplified ODE-based macroscale model for disconnected intracellular cells.

Inclusion of nonlinear membrane interface conditions in the homogenized model.

Abstract

Ion transport in biological tissues is crucial in the study of many biological and pathological problems. Some multi-cellular structures, like smooth muscles on the vessel walls, could be treated as periodic bi-domain structures, which consist of intracellular space and extracellular space with semipermeable membranes in between. With the aid of two-scale homogenization theory, macro-scale models are proposed based on an electro-neutral (EN) microscale model with nonlinear interface conditions, where membranes are treated as combinations of capacitors and resistors. The connectivity of intracellular space is also taken into consideration. If the intracellular space is fully connected and forms a syncytium, then the macroscale model is a bidomain nonlinear coupled partial differential equations system. Otherwise, when the intracellular cells are not connected, the macroscale model for intracellular space is an ordinary differential system with source/sink terms from the connected extracellular space.