Browsing by Author "Rinker, Kristina D."

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    Fluid flow and Smad2 affects the response of vascular endothelial cells in vitro and in vivo
    (2016-02-05) Tamez-Vielma, Linda Selene; Rinker, Kristina D.; Moore, Randy; Di Martino, Elena; Proud, David; Ungrin, Mark; Mahinpey, Nader
    Human aortic endothelial cells (HAECs) have been observed to respond to fluid flow and shear stress by activating different signalling molecules both in vitro and in vivo. An important example of these flow-activated molecules is Smad2. Smad2 is a signalling molecule and transcription factor that has shown to be indispensable for the maintenance of vascular integrity. The aim of this study was to understand the effect of shear stress and Smad2 knockdown on endothelial gene expression. HAEC were transfected with Smad2 siRNA, and exposed to steady laminar shear stress (10 dyne/cm2). Our results showed that Smad2 siRNA and shear stress significantly up-regulated genes involved in atherosclerosis, heart dysfunction, and angiogenesis. Furthermore, Smad2 siRNA had a negative impact on athero-protective genes under static conditions. This is the first reported Smad2 siRNA gene expression profile of endothelial cells. Our findings suggest that Smad2 may a have a protective role against cardiovascular diseases.
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    Fluid flow effects on nanoparticle localization in zebrafish vessels and cultured human endothelial cells
    (2017) Gomez, Maria Juliana; Rinker, Kristina D.; Childs, Sarah J.; Cramb, David T.; Di Martino, Elena
    Assessment of nanoparticle distribution in the vasculature is important for determining drug delivery, molecular imaging efficacy, and risk profiles. Even though most medical nanoparticle applications require a vascular administration, factors affecting nanoparticle association with vessel walls in the presence of fluid forces are poorly understood. We evaluated the effect of fluid flow on the distribution of 200 nm carboxylate-coated polystyrene nanoparticles in flow-exposed endothelial cell cultures and zebrafish embryos. We combined confocal imaging of nanoparticle injected transgenic zebrafish, 3D modeling, and computational fluid dynamics to assess nanoparticle distribution under flow. Highest nanoparticle localization occurred in regions of disturbed flow and low shear stress found at branch points and downstream of bumps and curves in the zebrafish vasculature. Similar findings were obtained in human endothelial cells in vitro. Overall, fluid shear stress magnitude, flow disturbances, and flow-induced changes in endothelial physiology contribute to the vascular localization of nanoparticles.
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    Fluid flow exposure promotes epithelial-to-mesenchymal transition and adhesion of breast cancer cells to endothelial cells
    (2021-10-12) Fuh, Kenneth F.; Shepherd, Robert D.; Withell, Jessica S.; Kooistra, Brayden K.; Rinker, Kristina D.
    Abstract Background Mechanical interactions between tumor cells and microenvironments are frequent phenomena during breast cancer progression, however, it is not well understood how these interactions affect Epithelial-to-Mesenchymal Transition (EMT). EMT is associated with the progression of most carcinomas through induction of new transcriptional programs within affected epithelial cells, resulting in cells becoming more motile and adhesive to endothelial cells. Methods MDA-MB-231, SK-BR-3, BT-474, and MCF-7 cells and normal Human Mammary Epithelial Cells (HMECs) were exposed to fluid flow in a parallel-plate bioreactor system. Changes in expression were quantified using microarrays, qPCR, immunocytochemistry, and western blots. Gene–gene interactions were elucidated using network analysis, and key modified genes were examined in clinical datasets. Potential involvement of Smads was investigated using siRNA knockdown studies. Finally, the ability of flow-stimulated and unstimulated cancer cells to adhere to an endothelial monolayer, migrate and invade membrane pores was evaluated in flow and static adhesion experiments. Results Fluid flow stimulation resulted in upregulation of EMT inducers and downregulation of repressors. Specifically, Vimentin and Snail were upregulated both at the gene and protein expression levels in flow stimulated HMECs and MDA-MB-231 cells, suggesting progression towards an EMT phenotype. Flow-stimulated SNAI2 was abrogated with Smad3 siRNA. Flow-induced overexpression of a panel of cell adhesion genes was also observed. Network analysis revealed genes involved in cell flow responses including FN1, PLAU, and ALCAM. When evaluated in clinical datasets, overexpression of FN1, PLAU, and ALCAM was observed in patients with different subtypes of breast cancer. We also observed increased adhesion, migration and invasion of flow-stimulated breast cancer cells compared to unstimulated controls. Conclusions This study shows that fluid forces on the order of 1 Pa promote EMT and adhesion of breast cancer cells to an endothelial monolayer and identified biomarkers were distinctly expressed in patient populations. A better understanding of how biophysical forces such as shear stress affect cellular processes involved in metastatic progression of breast cancer is important for identifying new molecular markers for disease progression, and for predicting metastatic risk.
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    Methicillin resistant Staphylococcus aureus adhesion to human umbilical vein endothelial cells demonstrates wall shear stress dependent behaviour
    (BioMed Central, 2011-03-22) Viegas, Kayla D.; Dol, Sharul S.; Salek, M. Mehdi; Shepherd, Robert D.; Martinuzzi, Robert M.; Rinker, Kristina D.
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    Transcriptomic Analysis for the Identification and Prioritization of Treatment of Abdominal Aortic Aneurysms
    (2020-01-13) Kennard, Jacob Justin; Rinker, Kristina D.; Moore Randy D.; Di Martino, Elena S.; McIntyre, John B.
    Abdominal aortic aneurysms are pathological dilations of the abdominal aorta, characterized by a high mortality rate, and a lack of effective prognostic predictors. As the disease progresses, the aortic wall becomes significantly degraded and eventually the structure is compromised, leading to rupture and often death. Understanding the changes in gene expression that correlate to altered hemodynamics and mechanical properties within the aorta can help elucidate the nature of this degradation and improve rupture risk predictions. The present study leverages a novel clinical study design to provide validation for a previously proposed non-invasive, in-vivo metric. The metric uses imaging information as well as computational fluid dynamics and in-vivo strain measurements to better assess aneurysm stability and improve risk management. This study demonstrated that areas of an aneurysm predicted to be of high risk by the relative rupture potential exhibited significant changes in gene expression related to disease progression. It was also demonstrated that the relative rupture potential better predicts gene expression related to disease progression than any single metric for aneurysm stability. In addition to validation of the relative rupture potential, evidence for the infiltration of specific immune cells in high risk areas was found, providing an excellent starting point for future studies investigating the peripheral blood of abdominal aortic aneurysm patients for markers of aneurysm presence or stability. These studies could lay the groundwork for a blood test to be used in conjunction with imaging technologies to further improve abdominal aortic aneurysm risk assessment.