Theses and Dissertations from UMD
Permanent URI for this communityhttp://hdl.handle.net/1903/2
New submissions to the thesis/dissertation collections are added automatically as they are received from the Graduate School. Currently, the Graduate School deposits all theses and dissertations from a given semester after the official graduation date. This means that there may be up to a 4 month delay in the appearance of a give thesis/dissertation in DRUM
More information is available at Theses and Dissertations at University of Maryland Libraries.
Browse
4 results
Search Results
Item INFLAMMATORY MACROPHAGE REGULATION OF ANGIOGENESIS AND SKELETAL MUSCLE PHENOTYPES(2023) Evans, William Stuart; Prior, Steven J; Kinesiology; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Chronic inflammation is a hallmark of cardiovascular disease; however, there is a lack of understanding of how systemic inflammation affects the peripheral skeletal muscle to potentially hasten frailty and functional declines in patients. The overarching objective of this dissertation was to determine whether this systemic inflammation is accompanied by macrophage infiltration of skeletal muscle and reductions in skeletal muscle capillarization and fiber size. Using animal models of a) heart failure (HF) induced by transverse aortic constriction (TAC), and b) skeletal muscle ischemia, this work illuminates changes that occur in skeletal muscle with cardiovascular disease-related inflammation. The first study demonstrated that pressure overload resulted in cardiac hypertrophy in male rats consistent with heart failure with preserved ejection fraction (HFpEF), while females did not show cardiac hypertrophy or HF. The second study demonstrated sex-specific differences in skeletal muscle, with TAC male rats exhibiting smaller fiber sizes and greater capillarization, and female TAC rats exhibiting lower capillarization than Sham counterparts. This study then investigated skeletal muscle macrophages to determine whether they might underly or contribute to these differences. There were fewer macrophages in the skeletal muscle of male TAC rats than male Sham rats, and macrophage conditioned medium from TAC rats produced less-developed capillary networks in an ex vivo, experimental assay. Finally, the third study investigated whether an acute bout of systemic inflammation, in the absence of HF, could alter the infiltration of macrophages, or skeletal muscle fiber size or capillarization. Hindlimb ischemia was used to induce acute, systemic inflammation that peaked after 1 day. This systemic inflammation increased the infiltration of macrophages into remote, non-ischemic skeletal muscle by day 7; however, muscle structure was preserved over this short time course. This dissertation demonstrates that cardiovascular disease-associated inflammation is linked with tissue-level changes in macrophages in a sex-specific manner. These changes accompany and may, over time, contribute to skeletal muscle fiber atrophy and changes in capillarization in cardiovascular disease patients.Item CONCENTRATION- AND TIME-DEPENDENT EFFECTS OF PROGESTERONE ON ENDOTHELIAL CELLS(2022) Kim, Katherine In-Wha; Prior, Steven J; Kinesiology; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)The termination of endogenous sex hormone release is thought to account for increases in cardiovascular disease (CVD) incidence in postmenopausal women. Thus, hormone replacement therapy may be a preventive measure against cardiovascular disease. To date, most research has been focused on estrogen treatment, but the effects of progesterone, a vasoactive hormone with effects on the endothelium, have received less attention. Two progesterone receptor subtypes, nuclear and membrane, are known to enact the effects of progesterone in endothelial cells which mediate the release of nitric oxide (NO). There is also some evidence that the two subtypes function in a coordinated manner. The aims of this thesis study are to assess the effects of different concentrations of progesterone on endothelial cells and isolate the actions of the progesterone receptor subtypes. Outcomes of this study include migration and proliferation assays to assess endothelial cell function and Western blotting to quantify endothelial nitric oxide synthase expression and phosphorylation. Progesterone and the membrane progesterone receptor agonist were found to inhibit migration and proliferation of human umbilical vein endothelial cells (HUVECs), while progesterone alone or in combination with the membrane progesterone receptor agonist increased endothelial nitric oxide synthase (eNOS) phosphorylation in HUVECs after 24 hours of incubation. While increased eNOS phosphorylation is thought to be beneficial to HUVEC function, other factors released in the presence of progesterone or progesterone receptor agonists may be scavenging bioavailable NO, thus reducing the angiogenic potential of HUVECs.Item Investigation of the molecular mechanisms of vascular endothelial dysfunction in Hutchinson-Gilford progeria syndrome through in vitro 2D and 3D models(2021) Gete, Yantenew; Cao, Kan; Cell Biology & Molecular Genetics; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Hutchinson-Gilford progeria syndrome (HGPS) is a rare genetic disorder with features of accelerated aging. Predominantly, HGPS is caused by a de novo point mutation in the LMNA gene (c.1824C > T; p.G608G) resulting in progerin, a toxic lamin A protein variant. Children with HGPS typically die from coronary artery diseases or strokes at an average age of 14.6 years. Endothelial dysfunction is a known driver of cardiovascular pathogenesis; however, it is currently unknown how progerin antagonizes endothelial function in HGPS. In this study, I used human iPSC-derived endothelial cell (iPSC-EC) models that cultured under both static and fluidic culture conditions. HGPS iPSC-ECs show reduced endothelial nitric oxide synthase (eNOS) expression and activity compared to healthy controls and concomitant decreases in intracellular nitric oxide (NO) level, which result in deficits in capillary-like microvascular network formation. In addition, expression of matrix metalloproteinase 9 (MMP-9) was reduced in HGPS iPSC-ECs while expression of tissue inhibitor metalloproteinases 1 and 2 (TIMP1 and TIMP2) were upregulated relative to healthy controls. Moreover, I used an adenine base editor (ABE7.10max-VRQR) to correct the pathogenic c.1824C > T allele in HGPS iPSC-ECs. Remarkably, ABE7.10max-VRQR correction of the HGPS mutation significantly reduced progerin expression to a basal level, rescued nuclear blebbing, increased intracellular NO level, normalized TIMPs , and restored angiogenic competence in HGPS iPSC-ECs. Furthermore, to elucidate the effects of progerin on endothelial cells and vascular remodeling, in collaboration with Dr. Truskey’s lab at Duke university, we developed tissue-engineered blood vessels (TEBVs) using iPSC-ECs and smooth muscle cells (iPSC-SMCs) from normal and HGPS patients. Relative to normal TEBVs, HGPS TEBVs showed reduced function and exhibited markers of cardiovascular disease associated with endothelium, including a reduction in both vasoconstriction and vasodilation with increased inflammation markers, VCAM-1 and E-selectin protein. Hence, the TEBV model has identified a role of the endothelium in HGPS. Together, the results of the study provide molecular insights of endothelial dysfunction in HGPS and suggest that ABE7.10max-VRQR could be a promising therapeutic approach for correcting HGPS-related cardiovascular phenotypes.Item Formulation and Delivery of Enhanced Extracellular Vesicles for Wound Repair(2021) Born, Louis Joseph; Jay, Steven M; Bioengineering; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Despite the development of a variety of therapies, complex wounds resulting from disease, surgical intervention, or trauma remain a major source of morbidity. Extracellular vesicles (EVs) have recently emerged as an alternative approach to address this issue. In particular, EVs derived from mesenchymal stem/stromal cells (MSCs) have been shown to improve wound healing, especially via enhanced wound angiogenesis. However, despite their clearly established potential, EVs have limitations that limit clinical relevancy, including low potency and rapid clearance from the body. Additionally, the ability to sustainably deliver EVs may enhance their efficacy in wound healing. Here, we leveraged the capability of EVs to be engineered via producer cell modification to investigate the therapeutic potential of EVs from MSCs transfected to overexpress a well-established pro-angiogenic long non-coding RNA HOX transcript antisense RNA (HOTAIR). We established that HOTAIR was able to be successfully loaded into MSC EVs (HOTAIR-MSC EVs) and delivered to endothelial cells in vitro with increased functional angiogenic activity. HOTAIR-MSC EVs injected intradermally around excisional wounds also showed increased angiogenic activity in vivo in two different species of rodents and improved wound healing in diabetic mice. We further report biomaterial-enabled sustained release of EVs using injectable hydrogel nanoparticles containing a composite of thiolated hyaluronic acid, maleimide functionalized poly(ε-caprolactone), and polyethylene glycol tetraacryalte as well as 3D-printed hydrogel discs composed of gelatin methacrylate for topical application. EVs released from the formulation of both of these biomaterials retained angiogenic bioactivity. Nanoparticles containing HOTAIR-MSC EVs were injected intradermally around an excisional wound in diabetic mice and were able to increase angiogenesis and improve wound healing. EVs released from 3D-printed EV-loaded GelMa hydrogels retained bioactivity in an in vitro endothelial scratch assay. Overall, these data suggest increasing the content of lncRNA HOTAIR in MSC EVs as a promising wound healing therapeutic. Additionally, establishing a biomaterial-enabled sustained release therapeutic represents a promising translational product for clinical implementation.