Electronic Thesis and Dissertation Repository

Thesis Format



Master of Science


Physiology and Pharmacology


Hess, David A.

2nd Supervisor

Flynn, Lauren E.



Cellular therapies to mediate vascular regeneration for critical limb ischemia (CLI) are under intense investigation. Endothelial colony forming cells (ECFCs) derived from umbilical cord blood have shown promise by integrating into new vasculature in small animal models of CLI. However, limited cell survival in the ischemic limb has prompted the development of biomaterials to help support cell delivery and promote recovery. The effects of culturing ECFCs in 3D hydrogels derived from the extracellular matrix on viability, proliferation and phenotype were characterized in vitro, and ECFC delivery in decellularized adipose tissue (DAT) hydrogels was assessed in NOD/SCID mice with hindlimb ischemia. DAT hydrogels supported high ECFC viability in vitro, with cell phenotype influenced by the hydrogel composition. While in vivo delivery within the DAT hydrogels did not significantly enhance cell retention or recovery of perfusion, future studies are warranted to investigate the incorporation of other supporting cell populations within the platform.

Summary for Lay Audience

Peripheral artery disease is caused when fat build-up occludes blood vessels and diminishes the blood supply leading to the lower limbs. In the most severe cases, peripheral artery disease develops into critical limb ischemia (CLI), where the exchange of nutrients, oxygen, and waste in the affected muscles is severely impaired, resulting in the development of resting limb pain, non-healing ulcers, and gangrene. CLI places an immense burden on patients, their families, and the health care system, and unfortunately, there are very limited treatment options available to patients. For this reason, interest in cell-based therapies making use of cell types with the capacity to stimulate the formation of new blood vessels in the affected tissues is under intense investigation. Endothelial colony forming cells (ECFCs) contribute to new blood vessel formation and have shown promising results to recover blood flow in small animal models of CLI. However, to translate this therapeutic potential to the clinic, further means of supporting ECFCs following transplantation into the muscles affected by CLI are required. Addressing this clinical need, this project explored the use of a new biomaterial made from proteins isolated from human adipose (fat) tissue normally discarded as surgical waste, which can form a gel at body temperature, referred to as a hydrogel. These hydrogels were used to encapsulate human ECFCs to support their survival and function and were also used to deliver ECFCs into a mouse model mimicking CLI. Through cell culture studies, the new adipose-derived hydrogels were compared to hydrogels made from similar types of proteins that were commercially sourced. It was found that the new hydrogels derived from adipose tissue effectively supported ECFC viability, with hydrogel composition influencing some markers of ECFC maturity. When the adipose-derived hydrogels were used to deliver ECFCs in vivo, they sustained ECFC survival at the site of injection similar to when cells were delivered in saline. The recovery of blood perfusion in mice with ischemic hindlimbs was also similar to when ECFCs were delivered in saline. Overall, these studies contribute to the development of clinically relevant biomaterials that can support regenerative cell types for CLI therapies.

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Available for download on Thursday, April 30, 2026