Isolation of angiogenic and arteriogenic subpopulations of peripheral blood CD31+ cells

Abstract

Cardiovascular disease (CVD) is the leading cause of death in the world and is predicted to remain so. Vascular growth and regeneration is a critical process necessary to the successful recovery of ischemic cardiovascular injuries and diseases. Unfortunately, postnatal vascular growth is difficult to achieve especially in the case of geriatric individuals who are likely to suffer from multiple cardiovascular complications. Though several studies have investigated various neovasculogenic cell types, these cell are either rare, inconsistently isolated or their effectiveness and existence is controversial. Recently, circulating CD31+ cells were found to strongly increase vascular perfusion in animal models of limb ischemia; however, this cell population is heterogeneous and the mechanism of their neovasculogenic effects is not well understood. Our lab identified lineage marker CD14 as a means of separating CD31+ cells into angiogenic and arteriogenic fractions. This thesis uses a series of rigorous in vitro assays to characterize the phenotype of peripheral blood CD31+CD14+ and CD31+CD14- cells. Cytometric and RNA expression analyses reveal the representation of vascular repair lineages and upregulation of angiogenic genes among the CD31+CD14+ cells and an arteriogenic expression profile among CD31+CD14- cells. The observed phenotypes were further investigated using mouse models of limb ischemia. Histological analysis supports that transplanted PB-CD31+CD14+ cells rapidly induce capillary growth and angiogenesis while injected PB-CD31+CD14- cells increase smooth muscle cell recruitment and arteriogenesis. Overall, this work demonstrates the angiogenic and arteriogenic natures of circulating CD31+CD14+ and CD31+CD14- cells, respectively. This thesis also helps to uncover the mechanisms through which the less understood process of arteriogenesis occurs. These insights are significant for the further development of effective cell therapies for cardiovascular disease.