Fluid Shear Stress Modulates S1P-Induced Endothelial Cell Invasion Into Three-Dimensional Matrices

Author(s):  
Hojin Kang ◽  
Kayla J. Bayless ◽  
Roland Kaunas

Endothelial cells are subjected to biochemical and mechanical stimuli which regulate their angiogenic potential. We determined the synergistic effects of sphingosine-1-phosphate (S1P) and fluid shear wall stress (WSS) on the invasion of human umbilical vein endothelial cells (HUVECs) into three-dimensional collagen matrices. A collagen gel was incorporated into a parallel-plate flow chamber to apply controlled WSS to the surface of HUVEC monolayers over a period of 24hr. Cell invasion into the gels required the presence of S1P, with the effects of S1P being enhanced by WSS to an extent comparable to growth factor (VEGF + FGF-2) stimulation. The number of invading cells depended on the magnitude of WSS, with a maximal induction at a WSS of ∼5 dyne/cm2. The enhancement of invasion by WSS coincided with the phosphorylation of Akt and MMP-2 activation. These results provide evidence that WSS is a positive modulator of S1P-induced EC invasion into collagen gels and may contribute to the localization of sprouting angiogenesis at regions of low WSS such as post-capillary venules.

2008 ◽  
Vol 295 (5) ◽  
pp. H2087-H2097 ◽  
Author(s):  
Hojin Kang ◽  
Kayla J. Bayless ◽  
Roland Kaunas

Endothelial cells are subjected to biochemical and mechanical stimuli, which regulate their angiogenic potential. We determined the synergistic effects of sphingosine-1-phosphate (S1P) and fluid wall shear stress (WSS) on a previously established model of human umbilical vein endothelial cell invasion into three-dimensional collagen matrices. Collagen matrices were incorporated into a parallel-plate flow chamber to apply controlled WSS to the surface of endothelial monolayers over a period of 24 h. Cell invasion required the presence of S1P, with the effects of S1P being enhanced by shear stress to an extent comparable with S1P combined with angiogenic growth factor stimulation. The number of invading cells depended on the magnitude of shear stress, with a maximal induction at a shear stress of ∼5 dyn/cm2, whereas the invasion distance was proportional to the magnitude of shear stress. The enhancement of invasion by 5.3 dyn/cm2 shear stress coincided with elevated phosphorylation of Akt and matrix metalloproteinase (MMP)-2 activation. Furthermore, invasion induced by the combined application of WSS and S1P was attenuated by inhibitors of MMPs (GM6001) and the phosphatidylinositol 3-kinase/Akt signaling pathway (wortmannin). These results provide evidence that shear stress is a positive modulator of S1P-induced endothelial cell invasion into collagen matrices through enhanced Akt and MMP-2 activation.


Author(s):  
Hojin Kang ◽  
Kayla J. Bayless ◽  
Roland Kaunas

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.


2005 ◽  
Vol 127 (3) ◽  
pp. 374-382 ◽  
Author(s):  
Tomas B. Owatverot ◽  
Sara J. Oswald ◽  
Yong Chen ◽  
Jeremiah J. Wille ◽  
Frank C-P Yin

Endothelial cells in vivo are normally subjected to multiple mechanical stimuli such as stretch and fluid shear stress (FSS) but because each stimulus induces magnitude-dependent morphologic responses, the relative importance of each stimulus in producing the normal in vivo state is not clear. Using cultured human aortic endothelial cells, this study first determined equipotent levels of cyclic stretch, steady FSS, and oscillatory FSS with respect to the time course of cell orientation. We then tested whether these levels of stimuli were equipotent in combination with each other by imposing simultaneous cyclic stretch and steady FSS or cyclic stretch and oscillatory FSS so as to reinforce or counteract the cells’ orientation responses. Equipotent levels of the three stimuli were 2% cyclic stretch at 2%∕s, 80dynes∕cm2 steady FSS and 20±10dynes∕cm2 oscillatory FSS at 20dyne∕cm2-s. When applied in reinforcing fashion, cyclic stretch and oscillatory, but not steady, FSS were additive. Both pairs of stimuli canceled when applied in counteracting fashion. These results indicate that this level of cyclic stretch and oscillatory FSS sum algebraically so that they are indeed equipotent. In addition, oscillatory FSS is a stronger stimulus than steady FSS for inducing cell orientation. Moreover, arterial endothelial cells in vivo are likely receiving a stronger stretch than FSS stimulus.


eLife ◽  
2015 ◽  
Vol 4 ◽  
Author(s):  
Nicolas Baeyens ◽  
Stefania Nicoli ◽  
Brian G Coon ◽  
Tyler D Ross ◽  
Koen Van den Dries ◽  
...  

Vascular remodeling under conditions of growth or exercise, or during recovery from arterial restriction or blockage is essential for health, but mechanisms are poorly understood. It has been proposed that endothelial cells have a preferred level of fluid shear stress, or ‘set point’, that determines remodeling. We show that human umbilical vein endothelial cells respond optimally within a range of fluid shear stress that approximate physiological shear. Lymphatic endothelial cells, which experience much lower flow in vivo, show similar effects but at lower value of shear stress. VEGFR3 levels, a component of a junctional mechanosensory complex, mediate these differences. Experiments in mice and zebrafish demonstrate that changing levels of VEGFR3/Flt4 modulates aortic lumen diameter consistent with flow-dependent remodeling. These data provide direct evidence for a fluid shear stress set point, identify a mechanism for varying the set point, and demonstrate its relevance to vessel remodeling in vivo.


1995 ◽  
Vol 269 (2) ◽  
pp. H550-H555 ◽  
Author(s):  
V. Ranjan ◽  
Z. Xiao ◽  
S. L. Diamond

The role of chronic fluid shear stress on endothelial constitutive nitric oxide synthase (cNOS) levels may have an important role in vessel diameter control. We subjected primary human umbilical vein endothelial cells (HUVEC) or bovine aortic endothelial cells (BAEC, passages 2-14) to steady laminar shear stress. In both cell types, the intracellular level of cNOS was elevated within 3 h of flow exposure at 25 dyn/cm2 and remained elevated at 6 and 12 h of flow exposure, compared with stationary controls, as indicated by digital immunofluorescence microscopy. Shear stress exposure for 6 h caused a 2.2 +/- 0.3- and 2.8 +/- 0.3-fold elevation of cNOS protein levels in BAEC (n = 3, P < 0.01) and HUVEC (n = 3, P < 0.01), respectively, in the presence or absence of 1 microM dexamethasone. Dexamethasone suppresses induction of the inducible NOS gene, indicating that cNOS was elevated by fluid shear stress. Flow exposure at 4 dyn/cm2 caused no enhancement of cNOS levels in either cell type. The flow induction of the cNOS protein levels was not blocked by preincubation of BAEC with 100-400 microM of NG-nitro-L-arginine methyl ester, indicating that flow-induced NO (or guanosine 3',5'-cyclic monophosphate) was not involved in the elevation of cNOS levels. Protein kinase C inhibitor H-7 (10 microM) had no effect on induction of NOS protein in BAEC exposed to 25 dyn/cm2. The cNOS mRNA levels were found to be elevated by two- to threefold in BAEC after 6 or 12 h of flow exposure at either 4 or 25 dyn/cm2, and this induction of NOS mRNA occurred in the presence of dexamethasone. The elevation of cNOS levels by chronic flow exposure may provide a mechanism for chronic regulation of vessel diameter by endothelial response to prevailing blood flow.


2012 ◽  
Vol 7 (1) ◽  
pp. 110-114 ◽  
Author(s):  
LIANG-LIANG SUN ◽  
LE ZHANG ◽  
XIANG-LAN MENG ◽  
FENG ZHANG ◽  
YUN ZHAO ◽  
...  

2013 ◽  
Vol 74 ◽  
pp. 36-40 ◽  
Author(s):  
Feng Zhang ◽  
Le Zhang ◽  
Liang-liang Sun ◽  
Xiang-lan Meng ◽  
Yun Zhao ◽  
...  

1996 ◽  
Vol 271 (3) ◽  
pp. C994-C1000 ◽  
Author(s):  
S. Li ◽  
R. S. Piotrowicz ◽  
E. G. Levin ◽  
Y. J. Shyy ◽  
S. Chien

The small molecular mass heat shock protein of 27 kDa (HSP27) has been shown to influence actin filament dynamics and endothelial cell behavior in ways similar to those observed during laminar flow. We have employed human umbilical vein endothelial cells to determine whether fluid shear stress affects HSP27 expression or phosphorylation. After a shear stress of 16 dyn/cm2, HSP27 became more highly phosphorylated, with maximum increase in phosphorylation levels (3-fold) attained by 30 min and sustained for at least 20 h. HSP27 antigen levels did not change; however, HSP27 mRNA levels decreased by 20% after 16 h. In bovine aortic endothelial cells stably transfected with the wild-type human HSP27 gene, shear stress induced the phosphorylation of both the exogenous human HSP27 and the endogenous bovine HSP25. The product of a transfected mutant HSP27 gene in which the putative phosphorylation sites Ser-15, Ser-78, and Ser-82 had been replaced with Gly was not phosphorylated. Thus the modulation of HSP27 and its activity by shear stress is mediated through a posttranslational mechanism and differs from the shear stress induction of immediate early genes at the level of transcription.


2006 ◽  
Vol 290 (1) ◽  
pp. H458-H452 ◽  
Author(s):  
Mirella Gouverneur ◽  
Jos A. E. Spaan ◽  
Hans Pannekoek ◽  
Ruud D. Fontijn ◽  
Hans Vink

Vascular endothelial cells are shielded from direct exposure to flowing blood by the endothelial glycocalyx, a highly hydrated mesh of glycoproteins, sulfated proteoglycans, and associated glycosaminoglycans (GAGs). Recent data indicate that the incorporation of the unsulfated GAG hyaluronan into the endothelial glycocalyx is essential to maintain its permeability barrier properties, and we hypothesized that fluid shear stress is an important stimulus for endothelial hyaluronan synthesis. To evaluate the effect of shear stress on glycocalyx synthesis and the shedding of its GAGs into the supernatant, cultured human umbilical vein endothelial cells (i.e., the stable cell line EC-RF24) were exposed to 10 dyn/cm2 nonpulsatile shear stress for 24 h, and the incorporation of [3H]glucosamine and Na2[35S]O4 into GAGs was determined. Furthermore, the amount of hyaluronan in the glycocalyx and in the supernatant was determined by ELISA. Shear stress did not affect the incorporation of 35S but significantly increased the amount of glucosamine-containing GAGs incorporated in the endothelial glycocalyx [168 (SD 17)% of static levels, P < 0.01] and shedded into the supernatant [231 (SD 41)% of static levels, P < 0.01]. Correspondingly with this finding, shear stress increased the amount of hyaluronan in the glycocalyx [from 26 (SD 24) × 10−4 to 46 (SD 29) × 10−4 ng/cell, static vs. shear stress, P < 0.05] and in the supernatant [from 28 (SD 11) × 10−4 to 55 (SD 16) × 10−4 ng·cell−1·h−1, static vs. shear stress, P < 0.05]. The increase in the amount of hyaluronan incorporated in the glycocalyx was confirmed by a threefold higher level of hyaluronan binding protein within the glycocalyx of shear stress-stimulated endothelial cells. In conclusion, fluid shear stress stimulates incorporation of hyaluronan in the glycocalyx, which may contribute to its vasculoprotective effects against proinflammatory and pro-atherosclerotic stimuli.


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