P721Shear stress induced unfolding of von willebrand factor may be involved in the premature development of myocardial infarction

2019 ◽  
Vol 40 (Supplement_1) ◽  
Author(s):  
I Melnikov ◽  
Y Avtaeva ◽  
S Kozlov ◽  
D Nozadze ◽  
Z Gabbasov
Keyword(s):  
Myocardial Infarction ◽  
Monoclonal Antibody ◽  
Von Willebrand Factor ◽  
Platelet Adhesion ◽  
Critical Value ◽  
Conformational Rearrangement ◽  
Shear Rates ◽  
Premature Myocardial Infarction ◽  
Von Willebrand ◽  
Willebrand Factor

Abstract Background Normally, von Willebrand factor (vWF) becomes highly reactive with platelets upon unfolding into a fibrillar conformation at critical shear rate (more than 5000 s–1), that may occur in stenotic arteries. At shear rates below critical value (1200–1300 s–1), which occur in intact coronary arteries, normally there is no conformational rearrangement of vWF. Pathologic unfolding of vWF at shear rates below critical value may increase a risk of the development of coronary thrombosis. There is little information on the role of shear stress induced conformational rearrangement of vWF in the development of myocardial infarction in young individuals. Purpose To investigate vWF-dependent platelet adhesion of patients with premature myocardial infarction at shear rates below critical value (1200–1300 s–1). Methods Using a microfluidic system, we measured platelet adhesion to a fibrinogen-coated optical surface at shear rates of 1200–1300 s–1 during 10 minutes. We assessed platelet-rich plasma of 8 male persons 40–52 years old, who had previous myocardial infarction at the age of 34–39. The control group comprised 6 healthy male volunteers 30–55 years old. We compared the intensity of scattered laser light measured in volts (V) at 10th minute. To study vWF-dependent platelet adhesion, we blocked GPIb receptor with monoclonal antibody to inhibit platelet interaction with vWF. To compare the intensity of vWF-dependent platelet adhesion with normally occurring adhesion to fibrinogen, we blocked GPIIb/IIIa receptor with monoclonal antibody. Results The inhibition of GPIb vWF-receptor decreased platelet adhesion to fibrinogen surface at shear rates of 1200–1300 s–1 by 17.8±4.7% in healthy volunteers and by 92±2.8% in persons with premature myocardial infarction (p<0.05). Inhibition of GPIIb/IIIa receptor decreased platelet adhesion by 91.5±3.8% in healthy volunteers and by 97.3±3.2% in persons with premature myocardial infarction. Conclusion Pathologic unfolding of vWF at shear rates below critical value may be involved in the development of premature myocardial infarction. Acknowledgement/Funding This work was supported by the grant of the Russian Science Foundation (project #16-15-10098)

Asialo von Willebrand Factor Enhances Platelet Adhesion to Vessel Subendothelium

1988 ◽  
Vol 60 (01) ◽  
pp. 030-034 ◽  
Author(s):  
Eva Bastida ◽  
Juan Monteagudo ◽  
Antonio Ordinas ◽  
Luigi De Marco ◽  
Ricardo Castillo
Keyword(s):  
Von Willebrand Factor ◽  
Platelet Adhesion ◽  
Human Albumin ◽  
Membrane Receptors ◽  
Shear Rates ◽  
High Shear Rates ◽  
Platelet Deposition ◽  
Platelet Spreading ◽  
Von Willebrand ◽  
Willebrand Factor

SummaryNative von Willebrand factor (N-vWF) binds to platelets activated by thrombin, ADP or ristocetin. Asialo vWF (As-vWF) induces platelet aggregation in absence of platelet activators. N-vWF mediates platelet adhesion to vessel subendothelium at high shear rates. We have investigated the role of As-vWF in supporting platelet deposition to rabbit vessel subendothelium at a shear rate of 2,000 sec-1, using the Baumgartner perfusion system. We have studied the effects of the addition of As-vWF (from 2 to 12 μg/ml) to perfusates consisting of washed red blood cells, 4% human albumin and washed platelets. Our results show a significant increase in platelet deposition on subendothelium (p <0.01) in perfusions to which As-vWF had been added. Blockage of the platelet glycoproteins Ib and IIb/IIIa (GPIb and GPIIb/IIIa) by specific monoclonal antibodies (LJIb1 and LJCP8, respectively) resulted in a decrease of platelet deposition in both types of perfusates prepared with N-vWF and As-vWF. Our results indicate that As-vWF enhances platelet deposition to vessel subendothelium under flow conditions. Furthermore, they suggest that this effect is mediated by the binding of As-vWF to platelet membrane receptors, which in turn, promote platelet spreading and adhesion to the subendothelium.

scholarly journals Platelet von Willebrand factor: evidence for its involvement in platelet adhesion to collagen

Blood ◽  
1987 ◽  
Vol 70 (4) ◽  
pp. 1214-1217
Author(s):  
E Fressinaud ◽  
D Baruch ◽  
C Rothschild ◽  
HR Baumgartner ◽  
D Meyer
Keyword(s):  
Shear Rate ◽  
Von Willebrand Factor ◽  
Platelet Adhesion ◽  
Von Willebrand Disease ◽  
High Shear ◽  
Shear Rates ◽  
High Shear Rates ◽  
Von Willebrand ◽  
Willebrand Factor

Although it is well established that plasma von Willebrand Factor (vWF) is essential to platelet adhesion to subendothelium at high shear rates, the role of platelet vWF is less clear. We studied the respective role of both plasma and platelet vWF in mediating platelet adhesion to fibrillar collagen in a parallel-plate perfusion chamber. Reconstituted blood containing RBCs, various mixtures of labeled washed platelets and plasma from controls or five patients with severe von Willebrand disease (vWD), was perfused through the chamber for five minutes at a shear rate of 1,600 s-1. Platelet-collagen interactions were estimated by counting the radioactivity in deposited platelets and by quantitative morphometry. When the perfusate consisted of normal platelets suspended in normal plasma, platelet deposition on the collagen was 24.7 +/- 3.6 X 10(6)/cm2 (mean +/- SEM, n = 6). Significantly less deposition (16 +/- 2.3) was observed when vWD platelets were substituted for normal platelets. In mixtures containing vWD plasma, significantly greater deposition (9 +/- 2.2) was obtained with normal than with vWD platelets (1 +/- 0.4) demonstrating a role for platelet vWF in mediating the deposition of platelets on collagen. Morphometric analysis confirmed these data. Our findings indicate that platelet, as well as plasma, vWF mediates platelet-collagen interactions at a high shear rate.

PRIMARY BINDING SITE OF VON WILLEBRAND FACTOR IN THE SUBENDOTHELIUM WHICH MEDIATES PLATELET ADHESION IS NOT COLLAGEN

1987 ◽  
Author(s):  
Philip G de Groot ◽  
Jan A van Mourik ◽  
Jan J Sixma
Keyword(s):  
Monoclonal Antibody ◽  
Von Willebrand Factor ◽  
Platelet Adhesion ◽  
Collagen Type ◽  
Collagen Type I ◽  
Extracellular Matrices ◽  
Type I ◽  
Type Iii ◽  
Von Willebrand ◽  
Willebrand Factor

We have studies the binding of von Willebrand factor (vWF) to extracellular matrices of endothelial cells and smooth muscle cells and to the vessel wall of human umbilical arteries in relation to its function in supporting platelet adhesion at high shear rates. CLB-RAg 38, a monoclonal antibody directed against vWF inhibits the binding of 125I-vWF extracellular matrices completely. The binding of 125I-vWF to subendothelium is not inhibited, because there are many different binding sites. CLB-RAg 38 inhibits platelet adhesion to extracellular matrices and subendothelium, in sofar as it is dependent on plasma vWF. CLB-RAg 38 has no effect on adhesion depending on vWF already bound to the matrix or subendothelium. CLB-RAg 38 does not inhibit binding of vWF to collagen type I and type III. Another monoclonal antibody against vWF, CLB-RAg 201, completely inhibits binding of vWF to collagen type I and type III. CLB-RAg 201 does not inhibit binding of 125I-vWF ot the extracellular matrices. CLB-RAg 201 partly inhibits platelet adhesion but this inhibition is also present when the adhesion depends on vWF already present in matrix or subendothelium, indicating that CLB-RAg 201 also inhibits the adhesion of platelets directly, this in contrast to CLB-RAg 38. The epitopes for CLB-RAg 201 and 38 were found on different tryptic fragments of vWF. These data indicate that vWF binds to subendothelium and to matrices of cultured cells by mechanism that is different from binding to collagen.

scholarly journals Uremic platelets have a functional defect affecting the interaction of von Willebrand factor with glycoprotein IIb-IIIa

Blood ◽  
1990 ◽  
Vol 76 (7) ◽  
pp. 1336-1340 ◽  
Author(s):  
G Escolar ◽  
A Cases ◽  
E Bastida ◽  
M Garrido ◽  
J Lopez ◽  
...  
Keyword(s):  
Von Willebrand Factor ◽  
Platelet Adhesion ◽  
Indirect Evidence ◽  
Flow Conditions ◽  
Experimental Conditions ◽  
Shear Rates ◽  
Functional Defect ◽  
Uremic Patients ◽  
Von Willebrand ◽  
Willebrand Factor

Abstract Uremic patients have an impaired platelet function that has been related to membrane glycoprotein (GP) abnormalities. Using a perfusion system, we have studied the interaction of normal and uremic platelets with vessel subendothelium (SE) under flow conditions. Reconstituted blood containing washed platelets, purified von Willebrand factor (vWF) (1 U/mL), and normal washed red blood cells was exposed to de- endothelialized rabbit segments for 10 minutes at two different shear rates (800 and 1,600 seconds-1). In some experiments a monoclonal antibody to the GPIIb-IIIa complex (EDU3) was added to the perfusates. With normal platelets, the percentage of the vessel covered by platelets (%CS) was 23.1% +/- 3.7% at 800 seconds-1 and 30% +/- 4.3% at 1,600 seconds-1. Platelets were observed in contact or forming monolayers on vessel SE. EDU3 inhibited the spreading of normal platelets. The %CS (11.1% +/- 3.3%) was statistically decreased (P less than .01) and most of the platelets were observed in contact with the vessel surface. These data indicate that, under flow conditions, the interaction of vWF with GPIIb-IIIa can support the spreading of normal platelets in the absence of exogenous fibrinogen. Under the same experimental conditions, the interaction of uremic platelets with SE was markedly impaired at both shear rates studied (P less than .01 v normal platelets). The presence of EDU3 did not modify the interaction of uremic platelets. These results confirm the impairment of the platelet adhesion observed in uremic patients. Furthermore, they indicate the presence of a functional defect in the interaction of vWF with GPIIb-IIIa. The fact that perfusions with normal and uremic platelets in the presence of an antibody to the GPIIb-IIIa complex did not show any differences gives indirect evidence on a functionally normal interaction vWF/GPIb in uremic patients.

scholarly journals Von Willebrand factor in the vessel wall mediates platelet adherence

Blood ◽  
1985 ◽  
Vol 65 (1) ◽  
pp. 85-90 ◽  
Author(s):  
HV Stel ◽  
KS Sakariassen ◽  
PG de Groot ◽  
JA van Mourik ◽  
JJ Sixma
Keyword(s):  
Monoclonal Antibody ◽  
Shear Rate ◽  
Von Willebrand Factor ◽  
Vessel Wall ◽  
Human Artery ◽  
Shear Rates ◽  
Platelet Adherence ◽  
Wall Shear ◽  
Von Willebrand ◽  
Willebrand Factor

Abstract A monoclonal antibody directed against the von Willebrand factor moiety (vWF) of factor VIII-von Willebrand factor (FVIII-vWF), which blocks ristocetin-induced platelet aggregation as well as the binding of FVIII- vWF to platelets in the presence of ristocetin, inhibited platelet adherence to human artery subendothelium when present in normal flowing blood. This monoclonal antibody, CLB-RAg 35, inhibited platelet adherence as a function of the shear rate. At wall shear rates below 500 s-1, platelet adherence was not affected, but at higher shear rates platelet adherence was gradually inhibited, reaching an average of 11% of the normal value at 2,500 s-1. Indirect immunofluorescence established the reactivity of CLB-RAg 35 with vWF present in artery subendothelium. Pretreatment of normal vessel walls with this antibody inhibited adherence of platelets in blood from a patient with severe homozygous von Willebrand's disease and in blood from normal individuals. The inhibition was shear-rate dependent and significant at high shear rates (2,500 s-1). By adding increasing amounts of purified FVIII-vWF to normal blood, the inhibition was gradually overcome. These data indicate that vWF present in the vessel wall contributes appreciably to platelet adherence. At high wall shear rates, platelet adherence is mediated virtually completely by both plasma FVIII-vWF and vWF in the vessel wall. At low wall shear rates (below 500 s-1), platelet adherence occurs independent of FVIII-vWF in plasma and vWF in the vessel wall.

Tissue Factor Firmly Immobilized on Surfaces Promotes Platelet Adhesion and Fibrin Formation in Studies with Circulating Human Blood: Importance of Shear Rate Conditions and FVIIa.

Blood ◽  
2006 ◽  
Vol 108 (11) ◽  
pp. 3925-3925
Author(s):  
Raul Tonda ◽  
Irene Lopez-Vilchez ◽  
Ana M. Galan ◽  
Fulgencio Navalon ◽  
Marcos Pino ◽  
...  
Keyword(s):  
Tissue Factor ◽  
Von Willebrand Factor ◽  
Platelet Adhesion ◽  
Statistical Significance ◽  
Low Molecular Weight ◽  
Shear Rates ◽  
Fibrin Formation ◽  
Closure Time ◽  
Von Willebrand ◽  
Willebrand Factor

Abstract While procoagulant activity of tissue factor (TF) has been widely investigated, its possible proadhesive properties towards platelets have not been studied in detail. We explored the interaction of platelets with human TF (hTF) firmly attached to a surface using anticoagulated blood with low molecular weight heparin (20 U/ml) at different shear rates. For studies at 250 s−1 and 600 s−1, TF adsorbed on a synthetic surface was exposed to circulating blood in flat perfusion devices. Deposition of platelets and fibrin formation were evaluated by morphometric, immunocytochemical and ultrastructural methods. For experiments at 5000 s−1, we used the PFA-100™ with experimental cartridges with collagen or collagen-hTF. Effect of rFVIIa was assessed in all experimental settings. Prothrombin fragment F1+2 levels were also measured. At 250 and 600 s−1 platelet interaction was 19.84±1.33% and 26.12±3.42% of the total surface respectively. Our inmunocytochemical results suggest that von Willebrand factor could mediate these interactions. Fibrin formation was significantly higher at 250 s−1 than at 600 s−1 (p&lt;0.05). FVIIa tended to increase platelet deposition without reaching statistical significance, and raised fibrin formation and thrombin generation (p&lt;0.05). Our At 5000 s−1, closure times in the PFA-100 were significantly shortened in the presence of hTF (154.09 ±14.69 s vs 191.45± 16.09 s with collagen alone; p&lt;0.05). Addition of rFVIIa did not result in a further reduction of closure time. Our studies demonstrate that hTF is reactive for platelets. von Willebrand factor could mediate these interactions. Recombinant FVIIa enhances the procoagulant action of hTF at low and intermediate shear rates, but has no impact on the hemostatic performance at very elevated shear rates.

scholarly journals Von Willebrand factor in the vessel wall mediates platelet adherence

Blood ◽  
1985 ◽  
Vol 65 (1) ◽  
pp. 85-90 ◽  
Author(s):  
HV Stel ◽  
KS Sakariassen ◽  
PG de Groot ◽  
JA van Mourik ◽  
JJ Sixma
Keyword(s):  
Monoclonal Antibody ◽  
Shear Rate ◽  
Von Willebrand Factor ◽  
Vessel Wall ◽  
Human Artery ◽  
Shear Rates ◽  
Platelet Adherence ◽  
Wall Shear ◽  
Von Willebrand ◽  
Willebrand Factor

A monoclonal antibody directed against the von Willebrand factor moiety (vWF) of factor VIII-von Willebrand factor (FVIII-vWF), which blocks ristocetin-induced platelet aggregation as well as the binding of FVIII- vWF to platelets in the presence of ristocetin, inhibited platelet adherence to human artery subendothelium when present in normal flowing blood. This monoclonal antibody, CLB-RAg 35, inhibited platelet adherence as a function of the shear rate. At wall shear rates below 500 s-1, platelet adherence was not affected, but at higher shear rates platelet adherence was gradually inhibited, reaching an average of 11% of the normal value at 2,500 s-1. Indirect immunofluorescence established the reactivity of CLB-RAg 35 with vWF present in artery subendothelium. Pretreatment of normal vessel walls with this antibody inhibited adherence of platelets in blood from a patient with severe homozygous von Willebrand's disease and in blood from normal individuals. The inhibition was shear-rate dependent and significant at high shear rates (2,500 s-1). By adding increasing amounts of purified FVIII-vWF to normal blood, the inhibition was gradually overcome. These data indicate that vWF present in the vessel wall contributes appreciably to platelet adherence. At high wall shear rates, platelet adherence is mediated virtually completely by both plasma FVIII-vWF and vWF in the vessel wall. At low wall shear rates (below 500 s-1), platelet adherence occurs independent of FVIII-vWF in plasma and vWF in the vessel wall.

scholarly journals Glycoprotein Ib, von Willebrand factor, and glycoprotein IIb:IIIa are all involved in platelet adhesion to fibrin in flowing whole blood

Blood ◽  
1990 ◽  
Vol 76 (2) ◽  
pp. 345-353 ◽  
Author(s):  
RR Hantgan ◽  
G Hindriks ◽  
RG Taylor ◽  
JJ Sixma ◽  
PG de Groot
Keyword(s):  
Platelet Aggregation ◽  
Shear Rate ◽  
Von Willebrand Factor ◽  
Whole Blood ◽  
Platelet Adhesion ◽  
Thrombus Formation ◽  
Shear Rates ◽  
Wall Shear ◽  
Von Willebrand ◽  
Willebrand Factor

We have investigated the molecular basis of thrombus formation by measuring the extent of platelet deposition from flowing whole blood onto fibrin-coated glass coverslips under well-defined shear conditions in a rectangular perfusion chamber. Platelets readily and specifically adhered to fibrin-coated coverslips in 5 minute perfusion experiments done at either low (300 s-1) or high (1,300 s-1) wall shear rates. Scanning electron microscopic examination of fibrin-coated coverslips after perfusions showed surface coverage by a monolayer of adherent, partly spread platelets. Platelet adhesion to fibrin was effectively inhibited by a monoclonal antibody (MoAb) specific for glycoprotein (GP) IIb:IIIa. The dose-response curve for inhibition of adhesion by anti-GPIIb:IIIa at both shear rates paralleled that for inhibition of platelet aggregation. Platelet aggregation and adhesion to fibrin were also blocked by low concentrations of prostacyclin. In contrast, anti- GPIb reduced adhesion by 40% at 300 s-1 and by 70% at 1,300 s-1. A similar pattern of shear rate-dependent, incomplete inhibition resulted with a MoAb specific for the GPIb-recognition region of von Willebrand factor (vWF). Platelets from an individual with severe von Willebrand's disease, whose plasma and platelets contained essentially no vWF, exhibited defective adhesion to fibrin, especially at the higher shear rate. Addition of purified vWF restored adhesion to normal values. These results are consistent with a two-site model for platelet adhesion to fibrin, in which the GPIIb:IIIa complex is the primary receptor, with GPIb:vWF providing a secondary adhesion pathway that is especially important at high wall shear rates.

scholarly journals On the role of von Willebrand factor in promoting platelet adhesion to fibrin in flowing blood

Blood ◽  
1995 ◽  
Vol 86 (11) ◽  
pp. 4158-4165 ◽  
Author(s):  
SC Endenburg ◽  
RR Hantgan ◽  
L Lindeboom-Blokzijl ◽  
H Lankhof ◽  
WG Jerome ◽  
...  
Keyword(s):  
Binding Site ◽  
Von Willebrand Factor ◽  
Platelet Adhesion ◽  
Enzyme Linked Immunosorbent Assay ◽  
Secondary Interaction ◽  
Shear Rates ◽  
High Shear Rates ◽  
Von Willebrand ◽  
Willebrand Factor

Platelet adhesion to fibrin at high shear rates depends on both the glycoprotein (GP) IIb:IIIa complex and a secondary interaction between GPIb and von Willebrand factor (vWF). This alternative link between platelets and vWF in promoting platelet adhesion to fibrin has been examined in flowing whole blood with a rectangular perfusion chamber. Optimal adhesion required both platelets and vWF, as shown by the following observations. No binding of vWF could be detected when plasma was perfused over a fibrin surface or when coated fibrinogen was incubated with control plasma in an enzyme-linked immunosorbent assay. However, when platelets were present during perfusion, interactions between vWF and fibrin could be visualized with immunoelectron microscopy. Exposure of fibrin surfaces to normal plasma before perfusion with severe von Willebrand's disease blood did not compensate for the presence of plasma vWF necessary for adhesion. vWF mutants in which the GPIIb:IIIa binding site was mutated or the GPIb binding site was deleted showed that vWF only interacts with GPIb on platelets in supporting adhesion to fibrin and not with GPIIb:IIIa. Complementary results were obtained with specific monoclonal antibodies against vWF. Thus, vWF must first bind to platelets before it can interact with fibrin and promote platelet adhesion. Furthermore, only GPIb, but not GPIIb:IIIa is directly involved in this interaction of vWF with platelets.

Distinct Functional Conformations of von Willebrand Factor A1 Domain in Support of Platelet-Surface or Platelet-Platelet Interactions.

Blood ◽  
2007 ◽  
Vol 110 (11) ◽  
pp. 5182-5182
Author(s):  
Gianmarco Podda ◽  
James R. Roberts ◽  
Richard A. McClintock ◽  
Zaverio M. Ruggeri
Keyword(s):  
Platelet Aggregation ◽  
Von Willebrand Factor ◽  
Conformational Changes ◽  
Platelet Adhesion ◽  
Shear Rates ◽  
Amino Terminal ◽  
A1 Domain ◽  
Von Willebrand ◽  
Willebrand Factor ◽  
Positively Charged

Abstract The adhesive protein, von Willebrand factor (VWF), is generally considered a key substrate for platelet adhesion to the vessel wall, yet its role in platelet cohesion (aggregation) may be equally important for normal thrombus formation. In either case, the function of VWF is mediated by the primary interaction of the VWF A1 domain (VWF-A1) with glycoprotein (GP) Ibα, a component of the GPIb-IX-V receptor complex on the platelet membrane. Because normal plasma VWF in solution and GPIb coexist in circulating blood without any appreciable interaction, it has been postulated that conformational changes occur when VWF becomes immobilized and/or under the effect of pathologically elevated shear stress, such that binding to the receptor becomes possible and resultis in platelet tethering to a surface and shear-induced aggregation. Changes of the molecular shape of VWF, from coiled to extended, have been shown under the effect of hemodynamic forces, but evidence for conformational changes within VWF-A1 has remained elusive. The crystal structure of VWF-A1 in complex with a GPIbα amino terminal fragment has revealed that the VWF-A1 residues involved in the interaction are comprised between positions 544–614 and, in particular, do not include several positively charged Arg and Lys residues located in helices α4 and 5 (residues 627–668). The latter appear as likely candidates to interact with negatively charged residues in GPIbα as a consequence of potential conformational changes induced by tensile stress on the bond following an initial ligand-receptor contact. We tested this hypothesis by evaluating the ability of selected VWF-A1 mutants to support platelet adhesion or aggregation, respectively, under controlled flow conditions. Methods. We expressed in insect cells and purified a series of VWF-A1 fragments comprising residues 445–733. One fragment had native sequence and 8 had single or multiple substitutions of positively charged amino acid residues in helices α4 and/or α5. None of the substituted residues contribute to contacts with GP Ibα in the known crystal structures of the corresponding complex, and all except one were between 8 and 20 angstroms away from the closest GPIbα residue. All the fragments were dimeric (d) owing to the presence of interchain disulfide bond(s). Results: Native dVWF-A1 in solution supported platelet aggregation in a laminar flow field. Of the 8 mutants, 5 had variably decreased function (up to 95% less aggregation) and 2 had increased function (up to 200% increase in aggregation). The same results were observed with platelet-rich plasma in suspension or by measuring platelet aggregate formation with blood cells perfused over immobilized VWF-A1 at wall shear rates as high as 10,000 1/s. In contrast, as judged by the number of tethered platelets and their rolling velocities, all mutants supported adhesion as well as or better that the native VWFA-1 at all shear rates tested (500–25,000 1/s). Conclusions: These results provide structural evidence for the existence of different VWF-A1 conformers that can modulate adhesive properties with distinct effects on platelet adhesion to a surface or platelet aggregation.

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