Bubble Motion in a Blood Vessel: Shear Stress Induced Endothelial Cell Injury

2009 ◽  
Vol 131 (7) ◽  
Author(s):  
K. Mukundakrishnan ◽  
P. S. Ayyaswamy ◽  
D. M. Eckmann
Keyword(s):  
Shear Stress ◽  
Endothelial Cell ◽  
Bubble Dynamics ◽  
Cell Injury ◽  
Numerical Solutions ◽  
Multiple Scales ◽  
Membrane Integrity ◽  
Cell Membrane Integrity ◽  
Stress Gradients ◽  
Stress Variations

Mechanisms governing endothelial cell (EC) injury during arterial gas embolism have been investigated. Such mechanisms involve multiple scales. We have numerically investigated the macroscale flow dynamics due to the motion of a nearly occluding finite-sized air bubble in blood vessels of various sizes. Non-Newtonian behavior due to both the shear-thinning rheology of the blood and the Fahraeus–Lindqvist effect has been considered. The occluding bubble dynamics lends itself for an axisymmetric treatment. The numerical solutions have revealed several hydrodynamic features in the vicinity of the bubble. Large temporal and spatial shear stress gradients occur on the EC surface. The stress variations manifest in the form of a traveling wave. The gradients are accompanied by rapid sign changes. These features are ascribable to the development of a region of recirculation (vortex ring) in the proximity of the bubble. The shear stress gradients together with sign reversals may partially act as potential causes in the disruption of endothelial cell membrane integrity and functionality.

scholarly journals Effects of plant extracts on antioxidant status and oxidant-induced stress in Caco-2 cells

2007 ◽  
Vol 97 (2) ◽  
pp. 321-328 ◽  
Author(s):  
S. Aisling Aherne ◽  
Joseph P. Kerry ◽  
Nora M. O'Brien
Keyword(s):  
Dna Damage ◽  
Plant Extract ◽  
Plant Extracts ◽  
Antioxidant Status ◽  
Cell Injury ◽  
Membrane Integrity ◽  
Neutral Red ◽  
Dna Integrity ◽  
Cell Membrane Integrity ◽  
Wide Range

Experimental evidence suggests that most herbs and spices possess a wide range of biological and pharmacological activities that may protect tissues against O2-induced damage. The objectives of the present study were: first, to determine the effects of plant extracts on the viability, membrane integrity, antioxidant status and DNA integrity of Caco-2 cells and second, to investigate the cytoprotective and genoprotective effects of these plant extracts against oxidative stress in Caco-2 cells. The plant extracts examined were rosemary (Rosmarinus officinalis L.), oregano (Origanum vulgare L.), sage (Salvia officinalis L.) and echinacea (Echinacea purpurea L.). Cell membrane integrity was assessed by the lactate dehydrogenase release assay. Viability was determined by the neutral red uptake assay (NRUA) and the concentration of compound that resulted in 50 % cell death (IC50) was calculated. Antioxidant status of the cells was assessed by measuring GSH content, catalase activity and superoxide dismutase activity. To examine their cytoprotective and genoprotective effects, Caco-2 cells were pre-treated with each plant extract for 24 h followed by exposure to H2O2. DNA damage was assessed by the comet assay and cell injury was determined by the NRUA. Rosemary was the most toxic (IC50 123 μg/ml) and echinacea the least toxic (IC50 1421 μg/ml). Sage was the only plant extract to affect the antioxidant status of the cells by increasing GSH content. Sage, oregano and rosemary protected against H2O2-induced DNA damage (olive tail moment and percentage tail DNA), whereas protection against H2O2-induced cytotoxicity was afforded by sage only.

scholarly journals SENCR stabilizes vascular endothelial cell adherens junctions through interaction with CKAP4

2018 ◽  
Vol 116 (2) ◽  
pp. 546-555 ◽  
Author(s):  
Qing Lyu ◽  
Suowen Xu ◽  
Yuyan Lyu ◽  
Mihyun Choi ◽  
Christine K. Christie ◽  
...  
Keyword(s):  
Shear Stress ◽  
Endothelial Cell ◽  
Noncoding Rna ◽  
Rna Binding ◽  
Adherens Junctions ◽  
Vascular Endothelial Cell ◽  
Membrane Integrity ◽  
Laminar Shear Stress ◽  
Loss Of Function ◽  
Laminar Shear

SENCR is a human-specific, vascular cell-enriched long-noncoding RNA (lncRNA) that regulates vascular smooth muscle cell and endothelial cell (EC) phenotypes. The underlying mechanisms of action of SENCR in these and other cell types is unknown. Here, levels of SENCR RNA are shown to be elevated in several differentiated human EC lineages subjected to laminar shear stress. Increases in SENCR RNA are also observed in the laminar shear stress region of the adult aorta of humanized SENCR-expressing mice, but not in disturbed shear stress regions. SENCR loss-of-function studies disclose perturbations in EC membrane integrity resulting in increased EC permeability. Biotinylated RNA pull-down and mass spectrometry establish an abundant SENCR-binding protein, cytoskeletal-associated protein 4 (CKAP4); this ribonucleoprotein complex was further confirmed in an RNA immunoprecipitation experiment using an antibody to CKAP4. Structure–function studies demonstrate a noncanonical RNA-binding domain in CKAP4 that binds SENCR. Upon SENCR knockdown, increasing levels of CKAP4 protein are detected in the EC surface fraction. Furthermore, an interaction between CKAP4 and CDH5 is enhanced in SENCR-depleted EC. This heightened association appears to destabilize the CDH5/CTNND1 complex and augment CDH5 internalization, resulting in impaired adherens junctions. These findings support SENCR as a flow-responsive lncRNA that promotes EC adherens junction integrity through physical association with CKAP4, thereby stabilizing cell membrane-bound CDH5.

Effects of Steady Spatial Wall Shear Stress Gradients on Endothelial Cell Morphology in Three-Dimensional Models

2007 ◽  
Author(s):  
Leonie Rouleau ◽  
Monica Farcas ◽  
Jean-Claude Tardif ◽  
Rosaire Mongrain ◽  
Richard Leask
Keyword(s):  
Endothelial Cells ◽  
Shear Stress ◽  
Endothelial Cell ◽  
Wall Shear Stress ◽  
Cell Morphology ◽  
Flow Direction ◽  
Stress Gradient ◽  
Spatial Gradient ◽  
Stress Gradients ◽  
Wall Shear

Endothelial cell (EC) dysfunction has been linked to atherosclerosis through their response to hemodynamic forces. Flow in stenotic vessels creates complex spatial gradients in wall shear stress. In vitro studies examining the effect of shear stress on endothelial cells have used unrealistic and simplified models, which cannot reproduce physiological conditions. The objective of this study was to expose endothelial cells to the complex shear shear pattern created by an asymmetric stenosis. Endothelial cells were grown and exposed for different times to physiological steady flow in straight dynamic controls and in idealized asymmetric stenosis models. Cells subjected to 1D flow aligned with flow direction and had a spindle-like shape when compared to static controls. Endothelial cell morphology was noticeable different in the regions with a spatial gradient in wall shear stress, being more randomly oriented and of cobblestone shape. This occurred despite the presence of an increased magnitude in shear stress. No other study to date has described this morphology in the presence of a positive wall shear stress gradient or gradient of significant shear magnitude. This technique provides a more realistic model to study endothelial cell response to spatial and temporal shear stress gradients that are present in vivo and is an important advancement towards a better understanding of the mechanisms involved in coronary artery disease.

Endothelial Cell Morphologic Response to Asymmetric Stenosis Hemodynamics: Effects of Spatial Wall Shear Stress Gradients

2010 ◽  
Vol 132 (8) ◽  
Author(s):  
Leonie Rouleau ◽  
Monica Farcas ◽  
Jean-Claude Tardif ◽  
Rosaire Mongrain ◽  
Richard L. Leask
Keyword(s):  
Endothelial Cells ◽  
Shear Stress ◽  
Endothelial Cell ◽  
Wall Shear Stress ◽  
Atherosclerotic Plaque ◽  
Morphological Changes ◽  
Stress Gradients ◽  
Spatial Gradients ◽  
Wall Shear

Endothelial cells are known to respond to hemodynamic forces. Their phenotype has been suggested to differ between atheroprone and atheroprotective regions of the vasculature, which are characterized by the local hemodynamic environment. Once an atherosclerotic plaque has formed in a vessel, the obstruction creates complex spatial gradients in wall shear stress. Endothelial cell response to wall shear stress may be linked to the stability of coronary plaques. Unfortunately, in vitro studies of the endothelial cell involvement in plaque stability have been limited by unrealistic and simplified geometries, which cannot reproduce accurately the hemodynamics created by a coronary stenosis. Hence, in an attempt to better replicate the spatial wall shear stress gradient patterns in an atherosclerotic region, a three dimensional asymmetric stenosis model was created. Human abdominal aortic endothelial cells were exposed to steady flow (Re=50, 100, and 200 and τ=4.5 dyn/cm2, 9 dyn/cm2, and 18 dyn/cm2) in idealized 50% asymmetric stenosis and straight/tubular in vitro models. Local morphological changes that occur due to magnitude, duration, and spatial gradients were quantified to identify differences in cell response. In the one dimensional flow regions, where flow is fully developed and uniform wall shear stress is observed, cells aligned in flow direction and had a spindlelike shape when compared with static controls. Morphological changes were progressive and a function of time and magnitude in these regions. Cells were more randomly oriented and had a more cobblestone shape in regions of spatial wall shear stress gradients. These regions were present, both proximal and distal, at the stenosis and on the wall opposite to the stenosis. The response of endothelial cells to spatial wall shear stress gradients both in regions of acceleration and deceleration and without flow recirculation has not been previously reported. This study shows the dependence of endothelial cell morphology on spatial wall shear stress gradients and demonstrates that care must be taken to account for altered phenotype due to geometric features. These results may help explain plaque stability, as cells in shoulder regions near an atherosclerotic plaque had a cobblestone morphology indicating that they may be more permeable to subendothelial transport and express prothrombotic factors, which would increase the risk of atherothrombosis.

scholarly journals Endothelial cell polarization and orientation to flow in a novel microfluidic multimodal shear stress generator

Lab on a Chip ◽  
2020 ◽  
Vol 20 (23) ◽  
pp. 4373-4390
Author(s):  
Utku M. Sonmez ◽  
Ya-Wen Cheng ◽  
Simon C. Watkins ◽  
Beth L. Roman ◽  
Lance A. Davidson
Keyword(s):  
Shear Stress ◽  
Endothelial Cell ◽  
Microfluidic Device ◽  
Cell Polarization ◽  
Orientation Analysis ◽  
Stress Gradients ◽  
Multiple Levels

Endothelial cell polarization and orientation analysis using a novel microfluidic device that can simultaneously generate multiple levels of shear stress and shear stress gradients for systematic mechanobiology studies under flow.

Characterization of a Sudden Expansion Flow Chamber to Study the Response of Endothelium to Flow Recirculation

1995 ◽  
Vol 117 (2) ◽  
pp. 203-210 ◽  
Author(s):  
George A. Truskey ◽  
Kevin M. Barber ◽  
Thomas C. Robey ◽  
Lauri A. Olivier ◽  
Marty P. Combs
Keyword(s):  
Reynolds Number ◽  
Shear Stress ◽  
Wall Shear Stress ◽  
Recirculation Zone ◽  
Numerical Solutions ◽  
Flow Chamber ◽  
Sudden Expansion ◽  
Shear Stresses ◽  
Stress Gradients ◽  
Wall Shear

In order to simulate regions of flow separation observed in vivo, a conventional parallel plate flow chamber was modified to produce an asymmetric sudden expansion. The flow field was visualized using light reflecting particles and the size of the recirculation zone was measured by image analysis of the particles. Finite element numerical solutions of the two and three-dimensional forms of the Navier-Stokes equation were used to determine the wall shear stress distribution and predict the location of reattachment. For two different size expansions, numerical estimates of the reattachment point along the centerline of the flow chamber agreed well with experimental values for Reynolds numbers below 473. Even at a Reynolds number of 473, the flow could be approximated as two-dimensional for 80 percent of the chamber width. Peak shear stresses in the recirculation zone as high as 80 dyne/cm2 and shear stress gradients of 2500 (dyne/cm2)/cm were produced. As an application of this flow chamber, subconfluent bovine aortic endothelial cell shape and orientation were examined in the zone of recirculation during a 24 h exposure to flow at a Reynolds number of 267. After 24 h, gradients in cell orientation and shape were observed within the recirculation zone. At the location of reattachment, where the wall shear stress was zero but the shear stress gradients were large, cells plated at low density were still aligned with the direction of flow. No preferred orientation was observed at the gasket edge where the wall shear stress and shear stress gradients were zero. At higher cell densities, no alignment was observed at the separation point. The results suggest that endothelial cells can respond to spatial gradients of wall shear stress.

scholarly journals Pyrrolidine dithiocarbamate restores endothelial cell membrane integrity and attenuates monocrotaline-induced pulmonary artery hypertension

2008 ◽  
Vol 294 (6) ◽  
pp. L1250-L1259 ◽  
Author(s):  
Jing Huang ◽  
Pawel M. Kaminski ◽  
John G. Edwards ◽  
Albert Yeh ◽  
Michael S. Wolin ◽  
...  
Keyword(s):  
Endothelial Cell ◽  
Cell Membrane ◽  
Pulmonary Artery ◽  
Membrane Integrity ◽  
Pulmonary Artery Hypertension ◽  
Pyrrolidine Dithiocarbamate ◽  
Cell Membrane Integrity ◽  
Protein Activation ◽  
Caveolin 1 ◽  
Cell Membrane Disruption

Monocrotaline (MCT)-induced pulmonary artery hypertension (PAH) in rats is preceded by an inflammatory response, progressive endothelial cell membrane disruption, reduction in the expression of caveolin-1, and reciprocal activation of STAT3 (PY-STAT3). Superoxide and NF-κB have been implicated in PAH. To evaluate the role of caveolin-1, PY-STAT3 activation, and superoxide in PAH, MCT-injected rats were treated daily with pyrrolidine dithiocarbamate (PDTC; starting on days 1, 3, and 14 × 2 wk), an inhibitor of inflammation and NF-κB activation. Hemodynamic data, the expression of inhibitory (I)-κBα, caveolin-1, and Tie2 (a membrane protein), activation of PY-STAT3 and NF-κB, and superoxide chemiluminescence were examined. Rats developed progressive PAH at 2 wk post-MCT. There was progressive reduction in the expression of caveolin-1, Tie2, and activation of PY-STAT3 in the lungs. Reduction in I-κBα expression was present at 2 and 4 wk post-MCT. Superoxide chemiluminescence and NF-κB activation were observed only at 2 wk post-MCT and both decreased by 4 wk post-MCT despite progressive PAH. PDTC (starting on days 1 and 3) rescued caveolin-1 and Tie2, reversed MCT-induced PY-STAT3 activation, and attenuated PAH. In addition, PDTC restored I-κBα expression and reduced superoxide chemiluminescence at 2 wk but did not inhibit NF-κB activation despite attenuation of PAH. PDTC had no effect on established PAH. Increased superoxide chemiluminescence and NF-κB activation appear to be a transient phenomenon in the MCT model. Thus the disruption of endothelial cell membrane integrity resulting in caveolin-1 loss and reciprocal activation of PY-STAT3 plays a key role in the MCT-induced PAH.

scholarly journals Ginsenoside Rg1-Notoginsenoside R1-Protocatechuic aldehyde attenuates low shear stress-induced vascular endothelial cell dysfunction

2020 ◽  
Author(s):  
Lei Zhang ◽  
Yuan Li ◽  
Xin Ma ◽  
Xiaojie Wang ◽  
Lingxiao Zhang ◽  
...  
Keyword(s):  
Shear Stress ◽  
Endothelial Cell ◽  
Cell Injury ◽  
Vascular Endothelial Cell ◽  
Akt Signaling ◽  
Tube Formation ◽  
Vascular Endothelial ◽  
Ginsenoside Rg1 ◽  
Low Shear Stress ◽  
Low Shear

Abstract Background The Fufang Danshen formula is widely used in traditional Chinese medicine for the clinical treatment of coronary heart disease. However, there is no literature reporting the anti-atherosclerotic effect and mechanism of its combination of active ingredients, namely Ginsenoside Rg1-Notoginsenoside R1-Protocatechuic aldehyde (PPR). The aim of this study was to investigate the anti-atherosclerotic effects in ApoE−/− mice and potential mechanism of PPR in low shear stress-injured vascular endothelial cell. Methods In vivo assay, ApoE−/−mice were randomly divided into three groups: model group, Rosuvastatin group, and PPR group, with C57BL/6J mice as control group. A variety of staining methods were utilized for the observation of aortic plaque. The changes of the blood lipid indexes were observed by an automatic biochemistry analyzer. ET-1, eNOS, TAX2, and PGI2 were analyzed by enzymelinked immunosorbent assay. In vitro, we used fluid shear system to induce cell injury and silenced Piezo1 expression in HUVECs by siRNA. We observed the morphological, proliferation, migration and tube formation activity changes of cells after PPR intervention. Quantitative Real-Time PCR and western blot analysis was applied to observe m RNA and protein expression. Results Results showed that PPR treatment reduced atherosclerotic area and lipid level and improved endothelial function in ApoE−/− mice. PPR significantly repaired cell morphology, reduced cell excessive proliferation and ameliorated migration and tube formation activity. In addition, we found that PPR could affect FAK-PI3K/Akt signaling pathways. Importantly, Piezo1 siRNA abolished the protection effects of PPR. Conclusions In summary, our results suggested that PPR ameliorated atherosclerotic plaque formation and endothelial cell injury by intervening the FAK-PI3K/Akt signaling pathways. Piezo1 is a possible target of PPR in the treatment of atherosclerosis. These results indicate that PPR may be apotential drug for atherosclerosis.

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