Purification and characterization of human platelet von Willebrand factor

Williams, Sybil B.; McKeown, Laurie P.; Krutzsch, Henry C.; Hansmann, Kristin; Gralnick, Harvey R.

doi:10.1111/j.1365-2141.1994.tb05077.x

Cited by 35 publications

(44 citation statements)

References 40 publications

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“…The reason(s) why plasma vWf does not fully compensate for loss of the platelet protein remains unclear. Differences in the multimer composition of plasma and platelet vWf (28), the ability of plasma fibrinogen to effectively compete with plasma vWf for binding sites on the surface of immobilized platelets (37), and the possibility of distinct binding sites for the platelet protein may partly explain the functional differ-ences between these two proteins. A key issue for future investigation will be to determine the relative contribution of the platelet and plasma pools of both vWf and fibrinogen in supporting the various stages of platelet thrombus growth and to delineate the mechanisms regulating surface immobilization of these individual adhesive substrates.…”

Section: Discussionmentioning

confidence: 99%

“…To date, a role for GPIbα in localizing platelet vWf to the cell surface has not been established. Platelet vWf binds to GPIbα with a significantly lower affinity than the plasma protein despite the fact that platelet vWf consists of higher-molecular-weight multimers (28) and that these multimers are preferentially expressed on the cell surface (29,30). Whether GPIbα can functionally compensate in the absence of integrin α IIb β 3 or an additional receptor is involved in vWf surface expression is an important issue for future investigation.…”

Section: Discussionmentioning

confidence: 99%

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A revised model of platelet aggregation

Kulkarni¹,

Dopheide²,

Yap³

et al. 2000

J. Clin. Invest.

327

236

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IntroductionPlatelet aggregation at sites of vascular injury is essential for the formation of the primary hemostatic plug and also for the development of pathological thrombi at sites of atherosclerotic plaque rupture. The initial contact of platelets with the injured vessel wall (platelet adhesion) is a complex process involving multiple adhesive substrates (von Willebrand factor [vWf], collagen) and receptors on the platelet surface (GPIb/V/IX, integrins α IIb β 3 and α 2 β 1 ) (1). The interaction between matrix-bound vWf and GPIbα on the platelet surface serves primarily to tether platelets to the area of vascular injury (2, 3), particularly under conditions of high shear stress, as a prerequisite step for integrin-mediated cell arrest (4). Whereas the molecular events underlying platelet adhesion under different shear conditions have been well delineated, the mechanism(s) by which platelets in freeflowing blood subsequently adhere to the initial layer of adherent platelets (platelet cohesion or aggregation) under flow have been less clearly defined.The traditional model of platelet aggregation, in which integrin α IIb β 3 was thought to have an exclusive role in mediating platelet-platelet adhesion contacts, has been largely determined from studies using a platelet aggregometer (5). With this method, the addition of a soluble agonist to a stirred platelet suspension induces activation of integrin α IIb β 3, converting it from a low-to a high-affinity receptor capable of binding soluble fibrinogen. The dimeric nature of fibrinogen enables it to cross-link adjacent activated platelets leading to stable platelet aggregation. Studies of platelet aggregation under high shear conditions, using a coneplate viscometer, have demonstrated that plasma vWf becomes the relevant ligand responsible for platelet activation (6). Shear-induced binding of soluble vWf to GPIbα initiates platelet activation independent of the addition of exogenous stimuli. Whereas the vWf-GPIbα interaction is indispensable for the initiation of platelet-platelet adhesion contacts under high shear, irreversible platelet aggregation requires a second adhesive interaction between vWf and integrin α IIb β 3 (7).The molecular events governing the formation of stable adhesion contacts between platelets in suspension have been well delineated; however, the mechanism by In this study we have examined the mechanism of platelet aggregation under physiological flow conditions using an in vitro flow-based platelet aggregation assay and an in vivo rat thrombosis model. Our studies demonstrate an unexpected complexity to the platelet aggregation process in which platelets in flowing blood continuously tether, translocate, and/or detach from the luminal surface of a growing platelet thrombus at both arterial and venous shear rates. Studies of platelets congenitally deficient in von Willebrand factor (vWf) or integrin α IIb β 3 demonstrated a key role for platelet vWf in mediating platelet tethering and translocation, whereas integrin α IIb β 3 mediated cell ...

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

A revised model of platelet aggregation

Kulkarni¹,

Dopheide²,

Yap³

et al. 2000

J. Clin. Invest.

327

236

View full text Add to dashboard Cite

show abstract

“…In particular, despite the fact that platelet-VWF is enriched in HMWM, it binds to platelet GpIba with significantly lower affinity compared with plasma-VWF. 11 In contrast, platelet-VWF demonstrates significantly enhanced binding to both GpIIbIIIa and heparin. 11 The molecular mechanisms responsible for these differences have not been defined, but are likely to relate to variations in the posttranslational modification of platelet-VWF (synthesized within megakaryocytes) as opposed to plasma-VWF (synthesized within endothelial cells).…”

Section: Introductionmentioning

confidence: 99%

“…11 In contrast, platelet-VWF demonstrates significantly enhanced binding to both GpIIbIIIa and heparin. 11 The molecular mechanisms responsible for these differences have not been defined, but are likely to relate to variations in the posttranslational modification of platelet-VWF (synthesized within megakaryocytes) as opposed to plasma-VWF (synthesized within endothelial cells). The N-and O-linked glycosylation profiles of plasma-VWF have been characterized in detail.…”

Section: Introductionmentioning

confidence: 99%

“…However, preliminary data suggest that these structures may differ significantly from those expressed on plasma-VWF. 11,14 In recent studies, we and others have clearly demonstrated the key role played by VWF glycans in regulating proteolysis by ADAMTS13. [15][16][17][18] Importantly, expression of both ABO blood group antigens and terminal sialic acid on VWF were shown to be of critical importance.…”

Section: Introductionmentioning

confidence: 99%

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Altered glycosylation of platelet-derived von Willebrand factor confers resistance to ADAMTS13 proteolysis

McGrath

Biggelaar

Byrne

et al. 2013

Blood

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Evaluation of von Willebrand factor concentrates by platelet adhesion to collagen using an in vitro flow assay

Riddell

Vinayagam

Gomez

et al. 2019

Research and Practice in Thrombosis and Haemostasis

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BackgroundVon Willebrand disease (VWD) results from quantitative or qualitative deficiency of von Willebrand factor (VWF) and is treated using VWF‐containing concentrates. Several studies have compared the function of various VWF containing concentrates however this has not been performed using shear based assays.ObjectivesTo compare the platelet‐capture potential of 10 commercially available, plasma‐derived VWF concentrates under shear conditions.Methods VWF containing concentrates were assessed for VWF:Ag, VWF:CB, VWF:RCo, factor VIII:C ADAMTS13 content, VWF multimeric profile and glycan content using lectin binding assays. Free‐thiol content of each concentrate was investigated using MPB binding assays. An in vitro flow assay was used to determine the ability of each concentrate to mediate platelet capture to collagen.Results VWF multimeric analysis revealed reduction of high molecular weight (HMW) forms in four of the concentrates (Alphante, Octanate and Haemoctin, and 8Y). The high MW multimer distribution of the remaining six concentrates (Optivate, Wilate, Fandhi, Wilfactin, Haemate P, and Voncento) was similar to the plasma control. Lectin analysis demonstrated that 8Y had increased amount of T‐antigen. Although platelet capture after 5 minutes perfusion was similar for all concentrates; Alphante, Octanate, and Haemoctin, demonstrated the lowest levels of platelet capture after 60 seconds of perfusion. Free‐thiol content and ADAMTS13 levels varied widely between the concentrates but was not correlated with function.ConclusionAlphanate, Octanate, and Haemoctin, lacked HMW multimers and had the lowest initial platelet capture levels suggesting that the presence of VWF HMW multimers are required for initial platelet deposition.

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Purification and characterization of human platelet von Willebrand factor

Cited by 35 publications

References 40 publications

A revised model of platelet aggregation

A revised model of platelet aggregation

Altered glycosylation of platelet-derived von Willebrand factor confers resistance to ADAMTS13 proteolysis

Evaluation of von Willebrand factor concentrates by platelet adhesion to collagen using an in vitro flow assay

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