Electronic Thesis and Dissertation Repository

Thesis Format

Monograph

Degree

Master of Science

Program

Physiology and Pharmacology

Supervisor

Hess, David

2nd Supervisor

Flynn, Lauren

Affiliation

Univeristy of Western Ontario

Co-Supervisor

Abstract

Due to limited treatment options for critical limb ischemia (CLI), cellular-based therapies have been investigated to induce blood vessel regeneration. Bone marrow-mesenchymal stromal/stem cells (BM-MSC) have shown pre-clinical success in animal models of CLI as they possess pro-angiogenic and immunomodulatory functions. However, clinical translation has been hindered by inadequate expansion and delivery strategies. This project aimed to characterize the phenotype and pro-angiogenic secretory function of BM-MSC on decellularized adipose tissue (DAT) bioscaffolds as expansion platforms. Compared to cells grown on tissue-culture plastic, DAT substrates supported BM-MSC growth, regenerative marker expression, and pro-angiogenic secretory function. Conditioned media generated by BM-MSC cultured on DAT coatings were enriched with factors associated with wound healing and significantly increased human endothelial cell survival under serum-free conditions in vitro. Overall, these studies show that DAT constructs present a promising tissue engineering approach to expand MSC while enhancing regenerative potential.

Summary for Lay Audience

Lower Extremity Arterial Disease (LEAD), also known as Peripheral Artery Disease (PAD), is caused by plaque accumulation in the blood vessels to the limbs, leading to reduced blood supply to the lower limbs. If the blood supply is reduced enough, patients will develop the most severe form of PAD known as critical limb ischemia (CLI). Patients with CLI present with resting limb pain, non-healing ulcers, and gangrene. Unfortunately, due to limited treatment options, many patients may require limb amputation and face a very high mortality rate. As a result, there has been interest in cellular-based therapies to regenerate new blood vessels in ischemic limbs. Bone marrow-derived mesenchymal stromal/stem cells (BM-MSC) are regenerative cells that have demonstrated promising therapeutic results in stimulating blood vessel formation in animal models of CLI. However, this benefit has not yet been translated clinically, as challenges with cell expansion and survival after injection have limited clinical progress. Generating enough cells for clinical use is a challenge as expanded cells lose regenerative abilities. Cell delivery is also difficult, with poor cell retention and survival after injection into the affected limbs. This project aimed to improve BM-MSC expansion by investigating alternative culturing methods using human fat-derived bioscaffolds. Compared to conventional culturing on plastic, fat-derived bioscaffolds increased the yield of viable BM-MSC and retention of cell markers associated with enhanced regenerative capacity. Additionally, culturing BM-MSC on fat-derived bioscaffolds enhanced their secretory abilities and their capacity to promote endothelial cell survival in vitro. Overall, this study aimed to enhance BM-MSC culture using biomaterials to improve MSC-based CLI therapies.

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