A. James Clark School of Engineering
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The collections in this community comprise faculty research works, as well as graduate theses and dissertations.
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Item UNDERSTANDING FUNCTIONAL BEHAVIORS OF ORGANOTROPIC TRIPLE NEGATIVE BREAST CANCER CELLS(2023) DeCastro, Ariana Joy; Stroka, Kimberly M; Bioengineering; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)11.7% of all cancer cases consist of breast cancer worldwide according to global cancer statistics. Triple negative breast cancer (TNBC) is subtype of breast cancer that has no expression of common hormonal receptors - estrogen receptor (ER), progesterone receptor (PR), and human epidermal growth factor receptor 2 (HER2). Due to this, TNBC is insensitive to endocrine or molecular targeted therapy and chemotherapy is the most effective treatment. Additionally, TNBC patients have reoccurrence within 3 years of diagnosis. Going further, due to the non-specific targeting of chemotherapy, cancer cells can develop drug resistance. The gold standard does not work in conjunction with microenvironmental factors to reduce disease progression and drug resistance. Not only is this disease lacking in effective treatments but is associated with a health disparity being most prevalent in pre-menopausal and African American women. There is clearlya need to understand the mechanisms of TNBC metastasis because of the impact not only on women in general but on women in historically marginalized communities. A significant innovation in determining cancer treatment is the use of genomic sequencing to identify mutations associated with metastasis. However, tumor heterogeneity puts limitations on fully understanding genomic landscape of TNBC, a highly mutational disease, using sequencing. Further, even when mutations are identified they may not be targetable, or patients may not respond to treatments. While genomic sequencing can be beneficial in improving treatment outcomes, they require further downstream validation of genetic expression to completely understand tumor biology and metastatic progression. This is where understanding the functional behavior of tumor cells with respect to their preferred secondary microenvironment can be advantageous in supplementing genomics data to get a comprehensive understanding of TNBC metastasis. The overall goal of this dissertation is to address this gap by quantifying tumor cell functional behavior and their response to microenvironmental cues. We evaluate three different physical and biochemical behaviors of TNBC tumor cells. In Chapter 3, the effect of TNBC secretome on endothelial barrier properties and function is explored. Chapter 4 quantifies the morphological and migratory phenotypes of brain and bone-seeking TNBC cells in response to ECM protein substrates found in their relevant microenvironments. Lastly, Chapter 5 will quantify the TNBC incorporation in response to brain relevant microenvironmental cues. Quantifying these functional behaviors could provide indicators of brain and bone tropic metastatic behavior and have broader impacts in creating a complete physical profile of organotropic TNBC metastasis.Item THE IMPACT OF ENGINEERED MECHANICAL CONFINEMENT ON MESENCHYMAL STEM CELL AND LUNG FIBROBLAST MECHANOBIOLOGY(2020) Doolin, Mary; Stroka, Kimberly M; Bioengineering; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Mechanical cues have been shown to influence cell gene expression, cell protein expression, and cell behaviors critical for homeostasis and disease progression. Cells experience the mechanical cue of confinement in vivo, such as within the extracellular matrix, and in vitro, such as within tissue engineered scaffolds. Despite its prevalence, the impact of mechanical confinement on cell fate is poorly understood. Cues from the mechanical microenvironment are primarily sensed and responded to by the cytoskeleton, which transmits forces to the nucleus and can thereby alter gene expression. The nucleus itself is also a mechanosensor, sensing external forces and again altering gene expression. Mesenchymal stem cells (MSCs) and lung fibroblasts are known to be sensitive to mechanical forces, yet the effect of mechanical confinement on these cells is unclear. In this dissertation, we investigated how mechanical confinement induced by engineered microchannels influences MSC morphology and migration. Notably, we show that confinement alters the relative contributions of cytoskeletal and contractile machinery in MSC migration in unconfined and confined spaces. We next investigated how mechanical confinement induced by microchannels influences MSC and fibroblast nucleus volume. When certain cytoskeletal machinery was inhibited, nucleus volume was altered only in MSCs in wide channels, suggesting diverging roles of the cytoskeleton in regulating nuclear deformation and migration in different degrees of confinement and in different cell types. While performing this work, we observed a lack of assays that provide precise control over the degree of confinement induced on cells, yield a large sample size, enable long-term culture, and enable easy visualization of cells over time. Therefore, we designed, created, and validated a confining micropillar assay that achieves these requirements. Using these confining micropillars, we investigated the effect of confinement on lung fibroblast to myofibroblast transition (FMT), a hallmark of idiopathic pulmonary fibrosis. Cell density was more predictive of FMT than the degree of confinement induced by micropillar arrays. These results improve our understanding of how MSCs and lung fibroblasts respond to confinement, which will aid in the rational design of MSC-based therapies and FMT-targeting therapies.