Date of Award

6-2016

Document Type

Thesis

Degree Name

Master of Science in Biology

Department

Biology

First Reader/Committee Chair

Nicole Bournias-Vardiabasis

Abstract

Conventional medical treatments fail to address the underlying problems associated with the damage inflicted by a coronary event. Thus, the long-term prognosis of patients admitted for heart failure is disheartening, with reported survival rates of 25 percent. Recent advances in stem cell research highlight the potential benefits of autologous stem cell transplantation for stimulating repair in heart tissue. However, a majority of those suffering from cardiovascular diseases are older adults whose autologous cells no longer possess optimum functional capacity. Additional work is needed to identify the optimal cell types or conditions that will promote cardiovascular regeneration across all age groups. A pretreatment, such as short-term hypoxia, and concurrent implementation of a novel progenitor, such as those that co-express Isl-1 and c-Kit, may enhance the results reported in clinical trials completed to date. However, the effects of short-term hypoxia in this novel cell type are unknown and warrant investigation in vitro.

Cloned adult and neonatal Isl-1+ c-Kit+ human cardiovascular progenitor cells were characterized and expanded for study. Populations from both age groups were preconditioned using short-term hypoxia (1% O2 for six hours) and, to identify shifts in gene expression, compared to their respective control (21% O2 at 37 °C) via qRT-PCR. Flow cytometry and western blot analysis was utilized to measure phosphorylation of Akt. Progression through the cell cycle was also analyzed by flow cytometry. Cellular function was evaluated by the use of a TUNEL assay and Transwell® invasion assay.

Hypoxia-mediated alterations of a genetic or functional nature in Isl-1+ c-Kit+ human cardiac progenitors are clearly age-dependent. Although both age groups accrued benefit, the neonatal progenitors procured significantly greater improvements. Short-term hypoxia significantly elevated Akt phosphorylation in neonatal Isl-1+ c-Kit+ human cardiac progenitors. Benefits afforded to both age groups by hypoxic pretreatment included significant upregulation of pro-survival transcripts, and enhanced invasion capabilities in vitro.

Therefore, prior to transplantation, hypoxic preconditioning may improve the ability of transplanted stem cells to home towards damaged areas of the heart and support cardiac regeneration in vivo.

Download

Share

COinS