Date of Award

2009

Degree Name

Biological Sciences

College

College of Science

Type of Degree

M.S.

Document Type

Thesis

First Advisor

Elmer Price

Second Advisor

Eric Blough

Third Advisor

Vincent Sollars

Abstract

The endothelium repairs itself through two methods. One is by the activity of circulating endothelial progenitor cells (EPCs). EPCs are immature endothelial cells that circulate the bloodstream that are capable of proliferation and differentiation into mature endothelium. It is thought that EPCs contribute to the repair and replacement of damaged endothelial cells in the process of reendothelialization. Physical inactivity and bed rest are known to be deleterious to the endothelium. It is possible that this inactivity is also deleterious to the number of viable EPCs, which would reduce the ability of the endothelium to repair itself. We used hind limb suspended rats as a model for physically inactive patients to examine its effects on circulating EPC populations. We hypothesized that HLS rats will exhibit fewer circulating EPCs than control rats. After obtaining a peripheral blood sample, the mononuclear cell fraction was stained with fluorescent antibodies and observed via flow cytometry. In addition, a fraction of mononuclear cells were cultured to determine colony forming potential. We did not find any significant differences in EPC numbers between control rats and HLS rats. The second means by which the endothelium repairs itself is through the migration of existing mature endothelial cells. To further understand the mechanics of the in vivo healing process, we subjected cultured human umbilical vein endothelial cells (HUVECs) to various drugs treatments and observed their effects on in vitro wound healing. We hypothesized that endothelial migration as a part of wound healing is controlled by cytoskeletal elements as well as secondary signals. Wounded cells were photographed on a time course and rate of healing was measured at each hour. We found that the rate of healing slows over time, and that disruption of cytoskeletal filaments slows wound healing. We concluded that HLS is not sufficient to induce a change in circulating EPC populations. In addition, we conclude that the microtubule components of the cytoskeleton are critical to endothelial resurfacing.

Subject(s)

Endothelial cells.

Wound healing.

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