The endothelium composes the inner lining of blood vessels, the heart, and lymphatic vessels. Within the cardiovascular system, it is an extremely important structure, aiding in the regulation of blood pressure with the vascular tone, recruiting immune response, regulating the transfer of material in and out of the bloodstream, and the creation of new blood vessels through angiogenesis. The endothelium is composed entirely of endothelial cells. These cells lay in a flat squamous formation and are in direct contact with blood and aid in the regulation and transfer of material in and out of the bloodstream via active and passive transport. Passive transport is regulated with cell-cell junctions between the endothelial cells, otherwise known as intercellular junctions, is the topic of interest in our first study. One cell-cell junction, adherens junctions are connected to the cytoskeleton of actin filaments. These actin filaments play an important role in the cell's ability to generate force through the contraction of the actin-myosin complex creating tension in the filaments. Because of the direct link between these two structures, there is a belief that there is a connection between the permeability of the endothelium and the cellular forces produced by the actin cytoskeleton. Also, other cell-cell junctions, gap junctions, and tight junctions have shown that when disrupted endothelial permeability increases. These junctions' relation between function and cell mechanics is not as well-known. Our goal is to determine if disruption of these junctions causes a similar stress environment as disruption of adherens junctions with the use of traction force microscopy and monolayer stress microscopy. The endothelium also plays an important role in the process of wound-healing. We look the endothelial cells role in wound-healing process as part of our second study. When an injury occurs and there is damaged tissue with inadequate oxygenation endothelial cells migrate into the wound space and begin the process of angiogenesis forming new blood vessels to support other cells in the process of wound-healing and providing oxygen to repair tissue. This process is so important that diseases that impede it can cause chronic wounds. To improve wound-healing rates, magnetic therapies have been looked at to stimulate the wound area and promote wound-healing. It is believed that cells are receptive to electrical and magnetic stimulation due to their ion-based communication methods. Magnetic field studies have shown promise in animal models. But contradictory results between different wound types and animal models leads us to look into an in-vitro human model to test the therapies potential effectiveness. To get a better idea of how magnetic therapy may affect human patients, we use human endothelial cells in an in-vitro scratch test study under several strength magnetic fields to determine if the therapies show any promise. Another therapy that shows promise is electrical stimulation. Studies show that the migration of single endothelial cells can be controlled using a voltage potential in-vitro. And in-vivo studies show promise in improving wound-healing times with diabetic ulcerations. To see if this improvement is potentially due to a collective migration response from the endothelial cells a similar set of scratch test in-vitro studies were conducted to see if endothelial wound-healing times improved under electrical stimulation. To determine the effectiveness of magnetic and electrical stimulations effect on wound-healing we look at the wound closure rate and average cell velocity of wounds created in these in-vitro models. Electrical stimulation has also shown promise as a wound-healing therapy with improvements in wound-healing for diabetic ulcers. Because of this improved wound-healing response from this therapy, we wish to look to see if endothelial cells are responsible for the improved wound-healing response. For electrical stimulation, a similar set of scratch tests were performed under a low voltage gradient to determine if collective cell migration and endothelial wound-healing were affected by electrical stimulation.
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Doctor of Philosophy (Ph.D.)
College of Engineering and Computer Science
Mechanical and Aerospace Engineering
Length of Campus-only Access
Doctoral Dissertation (Open Access)
Beverung, Sean, "Investigation of Endothelial Mechanics on Primary Cell Functions: Endothelium Permeability and Wound Healing" (2023). Electronic Theses and Dissertations, 2020-. 1514.