Electronic Thesis and Dissertation Repository

Degree

Doctor of Philosophy

Program

Physiology

Supervisor

David Hess

Abstract

Cardiovascular disease (CVD) remains a leading cause of premature death worldwide. Despite advances in treatment of ischemic diseases including myocardial infarction and peripheral arterial disease (PAD) there remains a need for effective revascularization therapies. Although early cell therapy trials investigated use of MNC from autologous bone marrow, emerging evidence indicates that purified progenitor cell populations are required to induce optimal vascular regeneration. In addition, autologous cells show reduced efficacy due to CVD-related progenitor dysfunction. This thesis presents preclinical studies characterizing several blood-derived cell types for the development of cellular therapies to treat PAD, focusing on the use of allogeneic umbilical cord blood (UCB) hematopoietic progenitor cells (HPC) and bone marrow multipotent stromal cells (MSC). First, I demonstrated that human UCB cells prospectively purified based on high aldehyde dehydrogenase activity (ALDHhi), promote the recovery of perfusion and vascularization in mice with acute unilateral hindlimb ischemia. Unfortunately, the rarity of ALDHhi cells impedes clinical implementation for patients with PAD. To address this issue, I developed ex vivo culture protocols to increase the number of ALDHhi cells available for therapy. I demonstrated that after a 20-fold increase in total cell number, expanded HPC maintained robust vascular regenerative functions. Indeed, expanded UCB promoted endothelial cell survival and endothelial cell tubule formation by paracrine mechanisms. Notably, intramuscular injection of HPC significantly augmented recovery of perfusion and increased vascularization in the injured limb, and increased recovery of limb usage within one week of therapy. MSC have been widely investigated for vascular regenerative cellular therapies, however substantial variability between donor sources indicating a need for better markers to select pro-angiogenic MSC subsets for clinical applications. I demonstrated that MSC retaining high ALDH activity after expansion effected increased endothelial cell proliferation, survival, and tubule formation using in vitro systems. Taken together, my work establishes the value of ALDH as a marker of cells with increased vascular regenerative potential. My work also reveals that UCB ALDHhi cells, their ex vivo expanded HPC progeny, and MSC retaining high ALDH-activity after expansion represent promising candidates for future development of vascular cell therapies for PAD and CVD.

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