Date of Award

May 2019

Document Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

Department

Bioengineering

Committee Member

Agneta Simionescu

Committee Member

Dan Simionescu

Committee Member

Martine LaBerge

Committee Member

Christopher Wright

Committee Member

John Bruch

Abstract

Diabetes Mellitus, characterized by high levels of blood sugar, is a significant risk factor for cardiovascular disease. Almost 25 million Americans are currently diagnosed with diabetes, with numbers rising rapidly. Hyperglycemia and dyslipidemia coexist in diabetes and result in inflammation, stiffening and degeneration in blood vessels which contributes to the development of atherosclerosis and arterial diseases such as coronary and peripheral artery disease. The diseased arteries can be replaced with synthetic materials, but the small-diameter arterial replacements (< 6 mm diameter) fail after 5-10 years because they are not resistant to the damage associated with diabetes. Tissue engineering offers a promising approach to develop decellularized extracellular matrix-based vascular scaffolds, repopulated with the patients’ own stem cells, to provide a non-immunogenic, patient-tailored vascular graft with improved remodeling and integration with native tissue. However, the presence of diabetes will structurally modify the implanted tissue engineered grafts. Therefore, it is necessary to develop tissue engineered vascular constructs capable of resisting diabetes-related alterations. The primary focus of this research was threefold: 1) Develop decellularized vascular scaffolds derived from porcine renal arteries with matrix integrity and mechanical properties similar to native blood vessels, 2) test the resistance of scaffolds treated with penta-galloyl glucose (PGG) to diabetes in functional small animal model, and 3) determine the immunomodulatory effect of adipose derived stem cell differentiation and seeding on scaffold remodeling in a diabetic environment.

First, a complete decellularization procedure of porcine renal arteries was established and optimized to remove all cellular and nuclear material from the scaffolds while still preserving the extracellular matrix components and mechanical properties. Treatment with PGG stabilized the matrix proteins and provided antioxidative properties.

An in vivo rat study was conducted to evaluate the scaffolds’ biocompatibility and ability to resist diabetes-related inflammation and glycoxidation. In comparing PGG-treated and non-treated groups, PGG-treatment consistently showed increased resistance to oxidative stress, inhibition of inflammatory cells and no limitations towards cell infiltration.

Lastly, adipose derived stem cells were harvested from the rats and differentiated into vascular cells (endothelial, smooth muscle, fibroblasts) and seeded onto the scaffolds before being implanted autologously. The rat study showed that the cell-seeded scaffolds had higher resistance to the inflammatory effects of diabetes and showed increased polarization of macrophages to the pro-healing M2 phenotype compared to the acellular scaffolds, and no limitations towards host cell infiltration.

The ultimate goal of this research was to develop a viable ECM based vascular graft that could survive long-term in a diabetic environment. It is expected that the progress made by this project will have a significant impact on those who suffer from diabetes-related vascular disease and complications. This translatable approach towards developing tissue engineered vascular grafts should allow clinicians to take one step closer to adopt this application for treating cardiovascular disease in diabetic patients and increase the success rate of their treatments.

Share

COinS