Document Type

Thesis - Open Access

Award Date

2021

Degree Name

Doctor of Philosophy (PhD)

Department / School

Biology and Microbiology

First Advisor

Mark Messerli

Keywords

cell viability, Electro-osmosis, Electrokinetic Perfusion, Electrophoresis, Extracellular matrix, Galvanotaxis

Abstract

Weak DC fields have been shown to induce polarity, cell migration and cell proliferation in 2D cultures in vitro. To understand the mechanism by which non-excitable cells sense such weak EFs, we have investigated the mechanism of cathode-directed water flow (electro-osmosis) in the boundary layer of cells by reducing it with neutral, viscous polymers. Our results indicate that low molecular weight polymers decrease cathodal migration and promote anodal migration in a concentration dependent manner. High molecular weight polymers do not affect directionality and can be explained using porosity and hydraulic permeability between the polymers. These results provide the first evidence for controlled reversal of galvanotaxis using viscous agents. We present a molecular flux model to describe electromigration of plasma membrane macromolecules and compare its predictions to electromigration of a lipid-anchored surface protein, tdTomato-GPI, under different experimental conditions. We also describe a method for identifying the physical properties of the plasma membrane proteins in zebrafish keratocytes to predict likely candidates for the cell surface electric field receptor that directs cathodal galvanotaxis, and to predict the asymmetric distribution of proteins in other cell types. In vivo, fluid flow through the vasculature generates mass transfer in the extracellular space and promotes cell proliferation and tissue survival. In the absence of sufficient flow, supply of nutrients and growth factors, and removal of waste products are limited by diffusion, resulting in the development of necrotic tissue. We propose that electrically driven water flow can overcome diffusion by generating interstitial flow to promote viability of the tissue. We have compared the efficacy of pressure driven perfusion with different types of electrokinetic perfusion toward reducing cell mortality in 3D cultures of Matrigel extracellular matrix. We report that electrokinetic perfusion significantly reduced mortality more consistently than pressure driven perfusion at similar flow rates. We conclude that electrokinetic perfusion has significant advantages over pressure driven perfusion for promoting tissue survival prior to neovascularization and angiogenesis.

Library of Congress Subject Headings

Electro-osmosis.
Cell migration.
Cells -- Motility.
Electrodiffusion.
Electrophoresis.
Tissues.

Format

application/pdf

Number of Pages

125

Publisher

South Dakota State University

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Rights Statement

In Copyright