In 2018, 1 in every 10 infants born in the United States was born preterm. The majority of neonatal deaths and nearly a third of infant deaths that occur are linked to preterm birth. Preterm birth is initiated when the quiescent state of the uterus ends prematurely, leading to contractions and parturition beginning as early as 32 weeks, though the origins are not well understood. Tocolytics are pharmaceuticals utilized to postpone preterm labor, but currently only manage to prolong pregnancy for up to 48 hours and have not proven effective in completely preventing preterm delivery. To enable research and discovery of therapeutics with potential to better address preterm birth, the capability to study isolated cell processes of pregnant uterine tissue in vitro is needed. Our development of an in vitro model of the myometrium utilizing uterine myocytes - uterine smooth muscle cells (uSMCs) responsible for contractions - provides a platform to examine the cellular mechanisms of late-stage pregnancy potentially involved in preterm birth. In this thesis, we discuss the optimized culture of uterine SMCs on a flexible polydimethylsiloxane (PDMS) substrate functionalized using a cationic solution, Poly-L-lysine (PLL), followed by extracellular matrix (ECM) protein coating. Using the model we developed, we then exposed this elastic substrate with uterine SMCs to different strain rates in order to investigate the impact of mechanical strain parameters on uterine SMC hypertrophy in the uterus during late-stage pregnancy. It was found that PLL and ECM protein coatings significantly impact cell morphology and density in unstrained substrates. It was also observed that when exposed to strain conditions, strain significantly increased hypertrophic morphological traits in select conditions. These results indicate that both surface and mechanical properties of in vitro systems impact uterine SMC phenotype, offering further understanding of cellular pathways involved in the uterus under mechanical load. / 2024-05-31T00:00:00Z

Despite advancements in percutaneous coronary intervention, stents are still limited by a 2% annual rate of in-stent restenosis (ISR) related to neointimal (NI) tissue proliferation. Efforts to prevent ISR formation remain the focus of ongoing work. Adenosine (ADO) is a purine nucleoside with integral roles in vascular homeostasis, though it has limited clinical application. ADO signals primarily via four receptors with ADO receptor-A2B (ADOR-A2B) considered to play an integral role in vascular healing. Dipyridamole (DP) is a commercially approved therapy known to improve vascular events and modulate adenosine biology. Our objectives with this study included (i) assessing whether ADO could serve as a biomarker of cardiac events; (ii) determine if DP could mitigate NI formation in a pre-clinical stent model; and, (iii) quantify the mechanisms of DP-related vasculoprotection, specifically related to ADOR-A2B. We assessed the analytic and biologic variability of circulating ADO levels in humans and demonstrated that circulating ADO was not predictive of cardiac events at one year following invasive coronary angiography. We then assessed whether modulation of adenosine biology with DP had therapeutic efficacy in a pre-clinical model. Utilizing meta-analysis, we confirmed the sustained effects of DP on vascular patency rates in both pre-clinical and clinical studies. We refined a pre-clinical rabbit model of stent implantation with assessment of stent healing by intravascular optical coherence tomography – with excellent translation to clinical observations. We then assessed DP in a pre-clinical model, demonstrating reduction in ISR and improved stent healing with DP compared to control. Last, we sought to elucidate the mechanisms behind the observed DP effects, specifically related to ADOR-A2B. In vivo, DP therapy demonstrated reduced NI smooth muscle cell (SMC) content. In vitro assessment of DP demonstrated dose-dependent inhibition of SMC proliferation and migration with alteration of SMC phenotypic switching, while selective modulation of ADOR-A2B and ADOR-A2B knockdown support an ADOR-A2B-mediated component to the observed DP effects. Adenosine biology is integral to vascular homeostasis. In humans, circulating adenosine levels in humans are not predictive of one year cardiovascular events. However, DP may improve vascular healing post stent implantation and warrants clinical evaluation for stent healing. The observed DP benefits may, in part, stem from ADOR-A2B modulation. ADOR-A2B is a viable target for assessment of small molecule modulation as a novel therapeutic target to improve vascular outcomes.

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<p>Allergic atopic asthma is a respiratory condition that involves immune responses to specific allergens resulting in coughing, wheezing, shortness of breath and tightness in the chest. During an atopic asthmatic attack, the immune system initiates cellular infiltration of lymphocytes and eosinophils, airway hyper-responsiveness and ECM remodeling, which manifests in lung dysfunction in chronic disease. ASMC have recently been shown to play a role in the inflammatory processes of asthma through the production of inflammatory mediators. Various cytokines and chemokines serve as stimulants for these pathways and therefore require further attention to examine inflammatory signaling. OSM, a member of the gp130 family of cytokines, is secreted by inflammatory cells and has been detected in the sputum of asthmatics. Previous findings have established the potential of OSM in induction of lung inflammation, its role in increasing ECM, and its potential role in asthma. Viral or bacterial infections cause asthma exacerbations which result in increased severity of symptoms. The innate immune system relies on pattern recognition receptors including the TLRs to recognize invading pathogens and activate cells such as macrophages and natural killer cells. Although there are a number of these TLRs, this project will focus on the role of TLR3 and TLR4 in ASMC. I generally hypothesized that OSM markedly increases lung cell airway smooth muscle cell responses to external stimulae, such as products of bacteria or viruses that activate toll-like receptors. This exacerbates inflammation and extracellular matrix remodeling which contributes to pathology in asthmatic patients. Findings in this thesis have demonstrated that OSM stimulation increases the production of various cytokines and chemokines and growth factors seen in asthma. Co-stimulations with OSM and TLR-ligands augmented the production of a variety of these inflammatory mediators in comparison to ligands alone. TLR responses were shown to be associated with TLR expression, at both the mRNA and protein level, as well through the activation of the JAK-STAT and NFκB pathways. These findings implicate ASMC in immunomodulatory roles in response to TLR-ligands and OSM, and could play a role in the increased severity of asthma seen during exacerbations.</p> / Master of Science (MSc)

<p> Calcium (Ca2+) is an important signaling molecule and hence its movement across cell membranes must be tightly regulated. The intracellular Ca2+ concentration ([Ca2+]i) in smooth muscle and endothelium controls the coronary tone. After stimulation, decreasing the [Ca2+]i back to resting levels is achieved mainly by the sodium calcium exchanger (NCX), the plasma membrane calcium pump (PMCA) or the sarcoendoplasmic reticulum calcium pump (SERCA). The present study will focus on NCX and its interactions with SERCA in the smooth muscle and endothelium of pig coronary artery.</p> <p> Aim 1 of my thesis is determination of activity levels of NCX in smooth muscle cells (SMC) and endothelial cells (EC). The NCX activity in cultured cells was approximately 5 times greater in EC than in SMC. The NCX inhibitors KB-R7943 and SEA 0400 blocked the NCX mediated Ca2+ entry, as did collapsing the Na+ gradient with monensin. NCX1 is the isoform largely responsible for NCX activity in SMC and EC. NCX activity was also assayed as the Ca2+ efflux in cultured cells and as Ca2+ uptake in plasma membrane vesicles isolated from freshly isolated smooth muscle.</p> <p> Aim 2 is to assess the existence of a functional NCX mediated Ca2+ entry linked to SERCA in SMC. In the absence of thapsigargin, BAPTA loading SMC increased the NCX mediated uptake. Thapsigargin did not affect the Ca2+ uptake in BAPTA loaded cells but it inhibited the Ca2+ uptake in cells that were not loaded with BAPTA. These data are consistent with a model in which SER acts as a sink for the NCX mediated Ca2+ entry. However, with BAPTA chelation and the resulting lower intracellular Ca2+, the need for SER to act as a sink is eliminated, and NCX is driven in full force. EC did not demonstrate a NCX-SERCA linkage.</p> <p> Arterial SMC and EC differ in their structure and function. The function of SMC is the generation of tone which is achieved by the Ca2+ dependent contractile filaments. Since these filaments are distributed throughout the cell, Ca2+ must be transported to and removed from deep within the cell. As a result, the SER may play a large role in Ca2+ regulation in the SMC. Furthermore, SMC also contain higher levels of high affinity Ca2+ pumps (SERCA and PMCA) and thus Ca2+ is more tightly regulated. Endothelial cells release nitric oxide in response to an increase in [Ca2+]i, which relaxes the smooth muscle. The endothelial nitric oxide sythase produces nitric oxide and is located adjacent to the PM in EC. The SER that removes Ca2+ from deep within the cell cytosol may play a small role in Ca2+ dependent modulation of the endothelial nitric oxide synthase activity. Based on the Western blot data, EC contain a greater amount of the high capacity NCX, thus the larger quantities of Ca2+ can be removed from the cell and the vicinity of endothelial nitric oxide synthase.</p> / Thesis / Master of Science (MSc)

Yes / Type 2 diabetes mellitus prevalence is growing globally, and the leading cause of mortality in these patients is cardiovascular disease. Epigenetic mechanisms such as microRNAs (miRs) and DNA methylation may contribute to complications of type 2 diabetes mellitus. We discovered an aberrant type 2 diabetes mellitus–smooth muscle cell phenotype driven by persistent up-regulation of miR-145. This study aimed to determine whether elevated expression was due to changes in methylation at the miR-145 promoter. Smooth muscle cells were cultured from saphenous veins of 22 non-diabetic and 22 type 2 diabetes mellitus donors. DNA was extracted, bisulphite treated and pyrosequencing used to interrogate methylation at 11 CpG sites within the miR-145 promoter. Inter-patient variation was high irrespective of type 2 diabetes mellitus. Differential methylation trends were apparent between non-diabetic and type 2 diabetes mellitus–smooth muscle cells at most sites but were not statistically significant. Methylation at CpGs −112 and −106 was consistently lower than all other sites explored in non-diabetic and type 2 diabetes mellitus–smooth muscle cells. Finally, miR-145 expression per se was not correlated with methylation levels observed at any site. The persistent up-regulation of miR- 145 observed in type 2 diabetes mellitus–smooth muscle cells is not related to methylation at the miR-145 promoter. Crucially, miR-145 methylation is highly variable between patients, serving as a cautionary note for future studies of this region in primary human cell types.