Effects of cyclic strain on the gene expression of human umbilical vein endothelial cells as determined through microarray technology
Frye, Stacie Renee
McIntire, Larry V.
Doctor of Philosophy
This thesis work resulted in microarray expression data of thousands of genes in vascular endothelial cells subjected to cyclic strain; and this data revealed genes showing expression changes between strained and control cells. The knowledge of gene expression changes due to cyclic strain helps reveal the mechanisms of vascular pathogenesis, which has been linked to the elevated levels of strain seen at arterial bifurcations and curves. Previous microarray studies on endothelial cells exposed to shear stress and smooth muscle cells subjected to cyclic strain indicated a number of genes that are responsive to hemodynamic forces in vascular cells. However, the studies in this thesis are the first to my knowledge to use microarray analysis to study vascular endothelial cells subjected to cyclic strain. Using microarrays equipped to study over 4000 genes simultaneously, expression levels of human umbilical vein endothelial cells exposed to cyclic strain (10%, 1 Hz), static control, and motion control for six and twenty-four hours indicated genes with differential expression between at least two of the three experimental conditions. Two different analysis methods, k-fold with a 2-fold threshold of significance and statistical testing with calculation of an adjusted p-value for significance, resulted in a total of 30 and 11 differentially expressed genes, respectively. Polymerase chain reaction verified the results of five genes and found that each method resulted in valid results. The k-fold method of analysis applied to expression data from two progressively higher wash temperatures of the microarrays resulted in an increasing number of differentially expressed genes. This study was the first to illustrate the strain-responsiveness of many of these differentially expressed genes. A number of the differentially expressed genes in this study fit into the functional classes of oxidative stress protection, regulation of proliferation or leukocyte recruitment, all of which are important to maintaining vascular health. Future in depth analysis of these differentially expressed genes will elucidate their functional activities in the cellular response to hemodynamic forces.
Biomedical engineering; Chemical engineering