Browsing by Subject "endothelial cells"

Now showing 1 - 3 of 3
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    Extracellular Matrix Guided Endothelial Differentiation
    (2022-08) Hall, Mikayla
    Cardiovascular disease is the leading cause of death worldwide. Due to recent advances including development of induced pluripotent stem cells, cardiac tissue engineering has emerged as a promising avenue for in vitro drug and device testing as well as eventual transplantation. Nutrient flow presents one of the major challenges to large scale engineered cardiac tissues which is necessary for many of the potential applications of engineered tissues. The lack of nutrient flow could be solved through tissue vascularization which requires endothelial cells lining vessels. The extracellular matrix (ECM) plays a vital role in tissue development and the majority of in vitro differentiation protocols rely on ECM substrates. Here we present two studies which investigate the role of the ECM in endothelial differentiation and the mechanisms activated by ECM engagement during differentiation. First, we investigate the role of individual ECM proteins in endothelial differentiation and elucidate pathways key to how ECM interactions promote differentiation. Second, a Design of Experiments approach was utilized to optimize the ECM composition for endothelial differentiation. The foundation of this work is a thorough knowledge of the role of the ECM during development, which guides protein selection and mechanistic investigation. An improved understanding of the role of ECM during in vitro differentiation will lead to better differentiation protocols and the potential for in situ differentiation. Ultimately, these studies will inform methods for engineered tissue vascularization to improve cell survival in large scale engineered tissues.
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    Microfluidic Model Systems to Evaluate Endothelial Cell Phenotype in Disease
    (2020-02) Hargis, Geneva
    Macrophages are known contributors to cancer progression in the primary site, but significantly less is known about their roles in secondary tumor formation. They are likely involved in tumor cell adhesion and transmigration of endothelial cells in the secondary site since macrophages are integral conductors of immune cell recruitment during the immune response and experimental evidence indicates that macrophages recruited to the secondary site before the arrival of tumor cells. However, current model systems are limited in their ability to observe and quantify these early interactions. We have developed a tunable, microfluidic model system consisting of an endotheilalized vessel channel perfusing a 3D collagen matrix that can be seeded with macrophages to recapitulate the basic structure of the extravasation site. We will use this model to quantify human macrophage-endothelial cell interactions in the context of metastasis by measuring permeability, tumor cell adhesion, and tumor cell transmigration. By treating devices with tumor cell conditioned media before the addition of tumor cells, we will quantify how macrophages change tumor cells extravasation phenotypes. We will also use M1 and M2 polarizing molecules to determine if macrophage polarization can create tumor-inhibitory or tumor-promoting responses. Since tumor cell adhesion and extravasation may depend on leukocyte adhesion mechanisms, we also developed a microfluidic model that can measure changes in leukocyte adhesion and velocity to endothelial cells in healthy and thrombotic states. We demonstrate that this model system may be used with endothelial and blood cells from a single patient, highlighting its utility in personalized medicine. Additionally, this model can be used to evaluate tumor cell-blood interactions and how these influence initial tumor cell adhesion in extravasation. As both these systems can probe and quantify early extravasation events, they can be used in tandem to gain a better understanding of the mechanisms driving tumor cell extravasation.
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    Recapitulating Dynamic Disease States from In Vitro to In Vivo: The Pathophysiology of Cell Fusion in Breast Cancer Metastasis and New Model Systems of Intracranial Aneurysm
    (2022-07) Chitwood, Casey
    Disease pathophysiology and potential therapies are studied using a variety of models. The specific models, or particular set of experiments, determine what questions can be answered about the disease model system. Here we look at three different model systems for studying both cell fusion in breast cancer metastasis and intracranial aneurysms. The bulk of this thesis work focuses on studying intracranial aneurysms. Intracranial Aneurysms (IAs) are weakened bulging points in blood vessels that upon rupture result in a devastating form of stroke known as a subarachnoid hemorrhage. Numerous features of IAs have been identified including the loss of elastin and collagen structure, increased immune infiltration, heightened cell activation and aberrant blood flow (hemodynamic forces). Although IAs have been studied for decades there are still no definitive causes for aneurysm stability vs growth and ultimately rupture. This is likely due to limited research focusing on creating links between the multiple driving forces of aneurysm progression. Unidentified hemodynamic forces are thought to be the main factor in the initiation of IA growth, yet there is almost no research that looks at both the aberrant flow patterns within IAs and the resulting biological response. While there are multiple methods of treatment, all come with high risk to the patient and are designed to mechanically occlude blood flow while ignoring the underlying biological mechanisms at play. Current model systems both in vivo and in vitro either lack physiological relevance or are limited in their ability to test therapeutic options through modified conventional means. Here, we have established an in vivo model of IA with increased physiologic relevance that can be utilized for the development of targeted therapeutic strategies and an in vitro model of IA that can be utilized to study the biological response of endothelial cells in response to specific blood flow patterns and the resulting hemodynamic forces.