The Elongation and Orientation of Cultured Endothelial Cells in Response to Shear Stress

1985 ◽  
Vol 107 (4) ◽  
pp. 341-347 ◽  
Author(s):  
M. J. Levesque ◽  
R. M. Nerem
Keyword(s):  
Endothelial Cells ◽  
Shear Stress ◽  
Cell Elongation ◽  
Vascular Endothelial Cells ◽  
Flow Direction ◽  
Flow Chamber ◽  
Shear Stresses ◽  
Cell Alignment ◽  
Aortic Endothelial Cells ◽  
Time Required

Vascular endothelial cells appear to be aligned with the flow in the immediate vicinity of the arterial wall and have a shape which is more ellipsoidal in regions of high shear and more polygonal in regions of low shear stress. In order to study quantitatively the nature of this response, bovine aortic endothelial cells grown on Thermanox plastic coverslips were exposed to shear stress levels of 10, 30, and 85 dynes/cm2 for periods up to 24 hr using a parallel plate flow chamber. A computer-based analysis system was used to quantify the degree of cell elongation with respect to the change in cell angle of orientation and with time. The results show that (i) endothelial cells orient with the flow direction under the influence of shear stress, (ii) the time required for cell alignment with flow direction is somewhat longer than that required for cell elongation, (iii) there is a strong correlation between the degree of alignment and endothelial cell shape, and (iv) endothelial cells become more elongated when exposed to higher shear stresses.

Fluid shear stress stimulates platelet-derived growth factor expression in endothelial cells

1993 ◽  
Vol 265 (1) ◽  
pp. H3-H8 ◽  
Author(s):  
M. Mitsumata ◽  
R. S. Fishel ◽  
R. M. Nerem ◽  
R. W. Alexander ◽  
B. C. Berk
Keyword(s):  
Endothelial Cells ◽  
Shear Stress ◽  
Growth Factor ◽  
Fluid Shear Stress ◽  
Critical Role ◽  
Fold Increase ◽  
Flow Chamber ◽  
Platelet Derived Growth Factor ◽  
Aortic Endothelial Cells ◽  
A Chain

Fluid flow and the associated shear stress play a critical role in vascular growth and remodeling. Recent data suggest that increased endothelial cell expression of platelet-derived growth factor (PDGF) A- and B-chain by flow may participate in these events. In the present study, we examined the mechanism for flow-induced PDGF expression, focusing on protein kinase C (PKC). Bovine aortic endothelial cells were exposed to flow (shear stress = 30 dyn/cm2) in a parallel-plate flow chamber. Increases in PDGF B-chain, but not PDGF A-chain, were observed within 3 h, maximal within 6 h (13-fold increase), and sustained for 24 h. PKC appeared to be involved because phorbol 12-myristate 13-acetate induced PDGF B-chain mRNA. Activation of PKC alone, however, was insufficient to induce PDGF mRNA because the selective PKC activator, 1-oleoyl-2-acetyl-sn-glycerol, did not induce PDGF expression. A PKC-independent pathway was suggested by the fact that inhibition of PKC (downregulation with phorbol 12,13-dibutyrate or exposure to staurosporine) failed to block PMA or flow-induced PDGF B-chain expression. These results demonstrate flow-induced PDGF B-chain expression in endothelial cells that appears to be mediated, in part, by a PKC-independent pathway.

Effects of Fluid Shear Stress on Endothelial Cell Invasion Into Three-Dimensional Matrices

2007 ◽  
Author(s):  
Hojin Kang ◽  
Kayla J. Bayless ◽  
Roland Kaunas
Keyword(s):  
Endothelial Cells ◽  
Shear Stress ◽  
Endothelial Cell ◽  
Cell Invasion ◽  
Fluid Shear Stress ◽  
Vascular Endothelial Cells ◽  
Umbilical Vein ◽  
Shear Stresses ◽  
Collagen Gels ◽  
Fluid Shear

We have previously developed a cell culture model to study the effects of angiogenic factors, such as sphingosine-1-phosphate (S1P), on the invasion of endothelial cells into the underlying extracellular matrix. In addition to biochemical stimuli, vascular endothelial cells are subjected to fluid shear stress due to blood flow. The present study is aimed at determining the effects of fluid shear stress on endothelial cell invasion into collagen gels. A device was constructed to apply well-defined fluid shear stresses to confluent human umbilical vein endothelial cells (HUVECs) seeded on collagen gels. Fluid shear stress induced significant increases in cell invasion with a maximal induction at ∼5 dyn/cm2. These results provide evidence that fluid shear stress is a significant stimulus for endothelial cell invasion and may play a role in regulating angiogenesis.

Wall Shear Stress Measurements in an Arterial Flow Bioreactor

2011 ◽  
Author(s):  
Elizabeth Voigt ◽  
Cara Buchanan ◽  
Jaime Schmieg ◽  
M. Nichole Rylander ◽  
Pavlos Vlachos
Keyword(s):  
Endothelial Cells ◽  
Shear Stress ◽  
Vascular System ◽  
Vascular Endothelial Cells ◽  
Shear Stresses ◽  
Bulk Flow Rate ◽  
Wall Shear ◽  
Endothelial Cell Response ◽  
And Function

Physiological flow parameters such as pressure and stress inside the vascular system strongly influence the physiology and function of vascular endothelial cells [1]. Variations in the shear stress experienced by endothelial cells affect morphology, alignment with the flow, mechanical strength, rate of proliferation, and gene expression [2]. Although it is known that these factors are dependent on the hemodynamics of the flow, the relationship has not been accurately quantified. In vitro bioreactor flow loops have been developed to simulate vascular flow for tissue conditioning and measurement of the endothelial cell response to varying shear [3–5]; however, wall shear stresses (WSS) have been estimated from the bulk flow rate by assuming Poiseuille flow [2, 6]. Due to the pulsatility of the flow, biochemical interactions, and the typically short vessel length, this assumption is fundamentally incorrect; however, the level of inaccuracy has not been quantified.

Exposure to fluid shear stress modulates the ability of endothelial cells to recruit neutrophils in response to tumor necrosis factor-α: a basis for local variations in vascular sensitivity to inflammation

Blood ◽  
2003 ◽  
Vol 102 (8) ◽  
pp. 2828-2834 ◽  
Author(s):  
Sajila Sheikh ◽  
G. Ed Rainger ◽  
Zoe Gale ◽  
Mahbub Rahman ◽  
Gerard B. Nash
Keyword(s):  
Endothelial Cells ◽  
Shear Stress ◽  
Tumor Necrosis Factor ◽  
Tumor Necrosis ◽  
Tumor Necrosis Factor Α ◽  
Fluid Shear Stress ◽  
Vascular Endothelial Cells ◽  
Shear Stresses ◽  
Factor Α ◽  
Necrosis Factor

Abstract Vascular endothelial cells are able to sense changes in the forces acting on them and respond, for instance, by modifying expression of a range of genes. However, there is little information on how such responses are integrated to modify homeostatic functions. We hypothesized that different shear stresses experienced in different regions of the circulation might influence endothelial sensitivity to inflammatory stimuli. We cultured human endothelial cells in tubes and exposed them for varying periods to shear stresses ranging from those typically found in postcapillary venules to those in arteries. When tumor necrosis factor-α was included in the flow cultures, we found startling differential effects of shear stress on the ability of endothelial cells to induce adhesion and migration of flowing neutrophils. Compared with static cultures, endothelial cells cultured at low shear stress (0.3 Pa) captured similar numbers of neutrophils but failed to induce their transendothelial migration. After exposure of endothelial cells to high shear stress (1.0 or 2.0 Pa), capture of neutrophils was largely ablated. The modification in response was detectable after 4 hours of exposure to flow but was much greater after 24 hours. From analysis of gene expression, loss of capture or migration was attributable to reduction in tumor necrosis factor–induced expression of selectins or CXC-chemokines, respectively. Thus, conditioning of endothelial cells by different flow environments may underlie variations in susceptibility to inflammation between different tissues or parts of the vascular tree.

Simultaneous Measurement of Morphology and Traction Forces of Endothelial Cells Under Fluid Shear Stress

2012 ◽  
Author(s):  
Toshiro Ohashi ◽  
Yusaku Niida ◽  
Ryoichi Tanaka ◽  
Masaaki Sato
Keyword(s):  
Endothelial Cells ◽  
Shear Stress ◽  
Fluid Shear Stress ◽  
Vascular Endothelial Cells ◽  
Morphological Changes ◽  
Traction Force ◽  
Flow Chamber ◽  
Fluid Shear ◽  
Traction Forces ◽  
Contractile Forces

Under fluid shear stress, vascular endothelial cells (ECs) cultured in a monolayer are known to exhibit marked elongation and orientation to the direction of flow [1]. It is also observed that intracellular F-actin filament distributions changed depending on the amplitude of shear stress and the direction of flow, suggesting morphology of ECs is closely related to cytoskeltal structure [2]. ECs generate contractile forces by the actin-myosin machinery and the forces are transmitted to underlying substrate as cellular traction forces. We hypothesize that reorganization of cytoskeletal structures regulates traction forces in ECs exposed to fluid shear stress. In order to measure traction forces and cell morphology simultaneously, we have developed a newly designed flow-imposed device in which a substrate with arrays of elastomeric micropillars (3 μm in diameter and 10 μm in height) is integrated on the bottom of a parallel plate flow chamber. In this study, traction force distributions and morphological changes in GFP-tagged ECs in a monolayer under fluid flow are simultaneously evaluated through image analysis in a spatial and a temporal manner.

Effects of Disturbed Flow On Endothelial Cells

1998 ◽  
Vol 120 (1) ◽  
pp. 2-8 ◽  
Author(s):  
J.-J. Chiu ◽  
D. L. Wang ◽  
S. Chien ◽  
R. Skalak ◽  
S. Usami
Keyword(s):  
Endothelial Cells ◽  
Shear Stress ◽  
Flow Direction ◽  
Arterial System ◽  
Shear Stresses ◽  
Stress Distributions ◽  
Complex Flow ◽  
Local Flow ◽  
Atherosclerotic Lesions

Atherosclerotic lesions tend to localize at curvatures and branches of the arterial system, where the local flow is often disturbed and irregular (e.g., flow separation, recirculation, complex flow patterns, and nonuniform shear stress distributions). The effects of such flow conditions on cultured human umbilical vein endothelial cells (HUVECs) were studied in vitro by using a vertical-step flow channel (VSF). Detailed shear stress distributions and flow structures have been computed by using the finite volume method in a general curvilinear coordinate system. HUVECs in the reattachment areas with low shear stresses were generally rounded in shape. In contrast, the cells under higher shear stresses were significantly elongated and aligned with the flow direction, even for those in the area with reversed flow. When HUVECs were subjected to shearing in VSF, their actin stress fibers reorganized in association with the morphological changes. The rate of DNA synthesis in the vicinity of the flow reattachment area was higher than that in the laminar flow area. These in vitro experiments have provided data for the understanding of the in vivo responses of endothelial cells under complex flow environments found in regions of prevalence of atherosclerotic lesions.

The Dynamic Response of Vascular Endothelial Cells to Fluid Shear Stress

1981 ◽  
Vol 103 (3) ◽  
pp. 177-185 ◽  
Author(s):  
C. F. Dewey ◽  
S. R. Bussolari ◽  
M. A. Gimbrone ◽  
P. F. Davies
Keyword(s):  
Endothelial Cells ◽  
Shear Stress ◽  
Endothelial Cell ◽  
Dynamic Response ◽  
Fluid Shear Stress ◽  
Vascular Endothelial Cells ◽  
Shear Stresses ◽  
Vascular Endothelial ◽  
Fluid Shear ◽  
Cell Functions

We have developed an in-vitro system for studying the dynamic response of vascular endothelial cells to controlled levels of fluid shear stress. Cultured monolayers of bovine aortic endothelial cells are placed in a cone-plate apparatus that produces a uniform fluid shear stress on replicate samples. Subconfluent endothelial cultures continuously exposed to 1–5 dynes/cm2 shear proliferate at a rate comparable to that of static cultures and reach the same saturation density (≃ 1.0–1.5 × 105 cells/cm2). When exposed to a laminar shear stress of 5–10 dynes/cm2, confluent monolayers undergo a time-dependent change in cell shape from polygonal to ellipsoidal and become uniformly oriented with flow. Regeneration of linear “wounds” in confluent monolayer appears to be influenced by the direction of the applied force. Preliminary studies indicate that certain endothelial cell functions, including fluid endocytosis, cytoskeletal assembly and nonthrombogenic surface properties, also are sensitive to shear stress. These observations suggest that fluid mechanical forces can directly influence endothelial cell structure and function. Modulation of endothelial behavior by fluid shear stresses may be relevant to normal vessel wall physiology, as well as the pathogenesis of vascular diseases, such as atherosclerosis.

Fluid shear stress modulates cytosolic free calcium in vascular endothelial cells

1992 ◽  
Vol 262 (2) ◽  
pp. C384-C390 ◽  
Author(s):  
J. Shen ◽  
F. W. Luscinskas ◽  
A. Connolly ◽  
C. F. Dewey ◽  
M. A. Gimbrone
Keyword(s):  
Endothelial Cells ◽  
Shear Stress ◽  
Fluid Shear Stress ◽  
Vascular Endothelial Cells ◽  
Free Calcium ◽  
Fluid Shear ◽  
Aortic Endothelial Cells ◽  
High K ◽  
Applied Shear Stress ◽  
Agonist Concentration

Cytosolic free Ca2+ concentration ([Ca2+]i) was monitored in single and groups of fura-2-loaded bovine aortic endothelial cells (BAEC) during exposure to laminar fluid shear stress. Application of a step increase in shear stress from 0.08 to 8 dyn/cm2 to confluent BAEC monolayers resulted in a transient increase in [Ca2+]i, which attained a peak value in 15-40 s, followed by a decline to baseline within 40-80 s. The magnitude of the [Ca2+]i responses increased with applied shear stress over the range of 0.2-4 dyn/cm2 and reached a maximum at greater than 4 dyn/cm2. Transient oscillations in [Ca2+]i with gradually diminishing amplitude were observed in individual cells subjected to continuous high shear stress. Elimination of extracellular Ca2+ with ethylene glycol-bis(beta-aminoethyl ether)-N,N,N',N'-tetraacetic acid, blockade of Ca2+ entry with lanthanum, depolarization of the cell membrane with high K+, and preconditioning of BAEC in steady laminar flow had little effect on the [Ca2+]i response. In the presence of ATP or ADP, application of shear stress caused repetitive oscillations in [Ca2+]i in single BAEC, whose frequency was dependent on both agonist concentration and the magnitude of applied shear stress. However, apyrase, an ATPase and ADPase, did not inhibit the shear-induced [Ca2+]i responses in standard medium (no added ATP or ADP), suggesting that the shear-induced [Ca2+]i response is not due to ATP released by endothelial cells.

Dual effect of fluid shear stress on volume-regulated anion current in bovine aortic endothelial cells

2002 ◽  
Vol 282 (4) ◽  
pp. C708-C718 ◽  
Author(s):  
Victor G. Romanenko ◽  
Peter F. Davies ◽  
Irena Levitan
Keyword(s):  
Endothelial Cells ◽  
Shear Stress ◽  
Fluid Shear Stress ◽  
Vascular Endothelial Cells ◽  
Aortic Endothelial Cells ◽  
Bovine Aortic Endothelial Cells ◽  
Biphasic Effect ◽  
Acute Changes ◽  
In Cells ◽  
Aortic Endothelial

The key mechanism responsible for maintaining cell volume homeostasis is activation of volume-regulated anion current (VRAC). The role of hemodynamic shear stress in the regulation of VRAC in bovine aortic endothelial cells was investigated. We showed that acute changes in shear stress have a biphasic effect on the development of VRAC. A shear stress step from a background flow (0.1 dyn/cm2) to 1 dyn/cm2 enhanced VRAC activation induced by an osmotic challenge. Flow alone, in the absence of osmotic stress, did not induce VRAC activation. Increasing the shear stress to 3 dyn/cm2, however, resulted in only a transient increase of VRAC activity followed by an inhibitory phase during which VRAC was gradually suppressed. When shear stress was increased further (5–10 dyn/cm2), the current was immediately strongly suppressed. Suppression of VRAC was observed both in cells challenged osmotically and in cells that developed spontaneous VRAC under isotonic conditions. Our findings suggest that shear stress is an important factor in regulating the ability of vascular endothelial cells to maintain volume homeostasis.

Sign in / Sign up

Export Citation Format

Share Document