Project description:Many studies have characterised the effect of normal laminar shear stress (LSS) on endothelial responses, however elevated shear stress, as would be experienced overlying a stenotic plaque, has not been studied in depth. Therefore we used transcriptomics and related functional analyses to compare cells exposed to laminar shear stress at 15 or 75 dynes/cm2 for 24 hours (LSS15-normal or LSS75-high shear stress). Human umbilical vein endothelial cells (HUVEC n=4 per flow condition from different batches of pooled donor HUVEC p2) were cultured for 24 hours on gelatin coated slides under laminar shear stress of either 15 dynes/cm2 or 75 dynes/cm2 (LSS15 or LSS75) to assess the effect of high shear stress on endothelial cells. Total RNA was obtained using Qiagen kit and array analysis performed by Service XS (Leiden, Netherlands).
Project description:Quiescence is a tempoary arrest from the cell cycle that can be induced by many methods, including contact inhibition, fluid shear stress, and serum starvation. p27 is important to inhibit cell cycle progression. Here we evaluate transcriptional differences between three different methods of quiescence induction, flow, contact inhibition and serum starvation, in the presence or depletion of p27.
Project description:Many studies have characterised the effect of normal laminar shear stress (LSS) on endothelial responses, however elevated shear stress, as would be experienced overlying a stenotic plaque, has not been studied in depth. Therefore we used transcriptomics and related functional analyses to compare cells exposed to laminar shear stress at 15 or 75 dynes/cm2 for 24 hours (LSS15-normal or LSS75-high shear stress).
Project description:Laminar shear stress due to constant blood flow is known to play a critical role in maintaining vascular health. In contrast, endothelial cell senescence appears to be closely associated with the incidence of vascular disorder. In an attempt to identify functional biomarkers for age-related vascular health/disease, the present study investigated differential gene expression of young and senescent human umbilical vein endothelial cells (HUVECs) under static and laminar shear stress. We used a cDNA microarray method to compare gene expression profiles of young and senescent HUVECs under static and laminar shear stress conditions. Experiment Overall Design: Senescent cells were prepared by continuous subculture in vitro, and a cone-and-plate device was used to impose laminar shear stress onto cells. Young and senescent cells were exposed to laminar shear stress or maintained under static conditions. Total mRNA was extracted and gene expression profiles were analyzed by cDNA microarray.
Project description:Laminar shear stress (LSS) suppresses endothelial inflammation and protects the arteries from atherosclerosis. Circular RNAs (circRNAs) are powerful regulators of vascular homeostasis and atherosclerosis; however, their roles in mediating the effects of LSS remain unexplored. To identify the changes in circRNA expression patterns after shear stress stimulation, we conducted circRNA microarray analysis using RNA extracted from HUVECs cultured for 24 h under static or LSS conditions.
Project description:Heterogeneity of endothelial cells that form the innermost layer of all vessels is critical for vascular sprouting and angiogenesis. After new vessels form, endothelial cell heterogeneity is believed to be gradually lost as vessels respond to flow-mediated signals, mature, remodel and become homeostatic. However, whether and at what level endothelial cell lost heterogeneity is poorly understood. Here we investigated heterogeneity change of endothelial cells under homeostatic laminar shear tress in comparison to static cultures.
Project description:Laminar shear stress due to constant blood flow is known to play a critical role in maintaining vascular health. In contrast, endothelial cell senescence appears to be closely associated with the incidence of vascular disorder. In an attempt to identify functional biomarkers for age-related vascular health/disease, the present study investigated differential gene expression of young and senescent human umbilical vein endothelial cells (HUVECs) under static and laminar shear stress. We used a cDNA microarray method to compare gene expression profiles of young and senescent HUVECs under static and laminar shear stress conditions. Keywords: stress response, age state analysis
Project description:Endothelial cells (ECs) are constantly submitted in vivo to hemodynamical forces derived from the blood circulation, including shear stress (SS). EC are able to detect SS and consequently adapt their phenotype, thus affecting many endothelial functions. If a plethora of shear stress-regulated molecular networks have been described in peripheral EC, less is known about the molecular responses of microvascular brain ECs which constitute the blood-brain barrier (BBB). In this work, we investigated the response of human cerebral microvascular ECs to laminar physiological shear stress using the well characterized hCMEC/D3 cell line. Interestingly, we showed that hCMEC/D3 cells responded to shear stress by aligning perpendicularly to the flow direction, contrary to peripheral endothelial cells which aligned in the flow direction. Whole proteomic profiles were compared between hCMEC/D3 cells cultured either in static condition or under 5 or 10 dyn.cm-2 SS for three days. 3592 proteins were identified and expression levels were significantly affected for 3% of them upon both SS conditions. Pathway analyses were performed which revealed that most proteins overexpressed by SS refer to the antioxidant defense, probably mediated by activation of the NRF2 transcriptional factor. Regarding down-regulated proteins, most of them participate to the pro-inflammatory response, cell motility and proliferation. These findings confirm the induction of EC quiescence by laminar physiological SS and reveal a strong neuroprotective effect of SS on hCMEC/D3 cells, suggesting a similar effect on the BBB. Our results also showed that SS did not significantly increase expression levels nor did it affect the localization of junctional proteins or the functional activity of several ABC transporters (P-glycoprotein and MRPs). This work provides new insights on the response of microvascular brain EC to SS and on the importance of SS for optimizing in vitro BBB models.
Project description:Laminar shear stress regulates blood vessel morphogenesis and subsequent quiescence, but how endothelial cells (EC) enact and maintain the vascular homeostasis required in most vessels for proper vessel function is poorly understood. SMAD6, a scaffold for several signaling pathways, is expressed in developing arteries and its expression is flow-regulated. We found that SMAD6 is essential for endothelial cell flow-mediated responses, and that it functions downstream of the mechanosensor Notch1. Endothelial cells with reduced SMAD6 levels failed to align under stable laminar shear flow that promotes vascular homeostasis, while forced SMAD6 expression rescued misalignment induced by reduced Notch1 signaling. SMAD6-dependent homeostatic laminar flow required the Notch ligand Dll4 and Notch transcriptional activity. Mechanistically, neither the N-terminal nor the C-terminal domain of SMAD6 alone rescued flow alignment upon loss of Notch signaling. Endothelial cells with reduced Smad6 levels has compromised barrier function, and RNA profiling revealed upregulation of proliferation-associated genes and down regulation of junction-associated genes. Among junction-related genes affected by SMAD6 levels, the proto-cadherin PCDH12 was upregulated by homeostatic flow and required for proper flow-mediated endothelial cell alignment. Thus, SMAD6 is a critical integrator of flow-mediated signaling inputs downstream of Notch1, as vessels transition from an angiogenic to a homeostatic phenotype.