scholarly journals SIN-1 reduces platelet adhesion and platelet thrombus formation in a porcine model of balloon angioplasty.

Circulation ◽  
1993 ◽  
Vol 87 (2) ◽  
pp. 590-597 ◽  
Author(s):  
P H Groves ◽  
M J Lewis ◽  
H A Cheadle ◽  
W J Penny
Keyword(s):  
Balloon Angioplasty ◽  
Platelet Adhesion ◽  
Porcine Model ◽  
Thrombus Formation ◽  
Platelet Thrombus

Identification of a Binding Site for Integrin αIIbβ3 in the von Willebrand factor (VWF) A1 Domain: Dual Roles for the A1 Domain in Platelet Thrombus Formation.

Blood ◽  
2004 ◽  
Vol 104 (11) ◽  
pp. 3658-3658
Author(s):  
Junmei Chen ◽  
Miguel A. Cruz ◽  
José A. López
Keyword(s):  
Binding Site ◽  
Binding Sites ◽  
Platelet Adhesion ◽  
Thrombus Formation ◽  
Shear Stresses ◽  
Platelet Surface ◽  
Rgd Sequence ◽  
Platelet Thrombus ◽  
A1 Domain ◽  
Von Willebrand

Abstract In 1999, Wu et al found that blood from patients with type 3 von Willebrand disease (lacking VWF in both plasma and platelets) could not form thrombi on a collagen surface (Arterioscler. Thromb. Vasc Biol2000, 201661–1667). This suggested that VWF was absolutely required for the accumulation of platelets in thrombi under flow, even in the presence of fibrinogen. Platelets have two VWF receptors, the GP Ib-IX-V complexes and αIIbβ3 , the former mediating the initial tethering and attachment of platelets onto VWF and the latter being involved in platelet-platelet contacts. GP Ib-IX-V binds VWF within the A1 domain and αIIbβ3 is known to bind an Arg-Gly-Asp (RGD) sequence in the C1 domain. In the study of Wu et al, reconstitution of the VWF-deficient plasma with recombinant VWF missing the A1 domain failed to restore thrombus formation, even when the collagen surface was first coated with wild-type VWF to allow platelet attachment. The A1 domain is thus important not only for initial platelet adhesion but also for thrombus accumulation, possibly by binding another platelet receptor. Consistent with this, the number of binding sites for the isolated A1 domain on the platelet surface is more than twice the number of GP Ibα polypeptides. The receptor responsible for these binding sites is unknown but αIIbβ3 is a good candidate given its high copy number and the marked defect seen in platelet thrombus formation in its absence or blockade. Of interest, while deletion of A1 prevented thrombus formation in the studies of Wu et al, mutation of the VWF RGD sequence did not. We therefore examined whether αIIbβ3 also binds within the VWF A1 domain. We found the following. 1) Purified, unactivated αIIbβ3 binds to immobilized A1 domain, binding blocked by antibodies to either αIIbβ3 or A1. 2) Unactivated αIIbβ3 does not interact with immobilized full-length VWF, but binds VWF in the presence of ristocetin. The binding of αIIbβ3 to both VWF and isolated A1 is blocked by the αIIbβ3 antibody c7E3 but not by RGD peptides, and by the A1 antibody 6G1. This suggests that the αIIbβ3 binding site in the A1 domain may overlap the 6G1 epitope (residues 700-709), which is distinct from the GPIbα binding site. 3) 6G1 inhibits shear-induced platelet aggregation—a process that requires both GP Ibα and αIIbβ3—without blocking GP Ibα binding. 4) Platelets firmly adhere on the surface containing A1 and cross-linked collagen-related peptide (CRP), a potent GP VI agonist, at high shear stresses. The CRP-GP VI interaction is not strong enough to arrest platelets under flow, suggesting that GP VI signals could activate αIIbβ3, and αIIbβ3 could mediate firm adhesion. Consistent with this, the αIIbβ3 antibody c7E3 prevented firm platelet adhesion. In summary, we find that αIIbβ3 binds to the A1 domain, in or near the sequence of Glu700-Asp709. In addition to its apparent role in platelet-platelet interactions during thrombus growth, the binding of αIIbβ3 to the VWF A1 domain may also facilitate the binding of GP Ibα to a distinct region of A1, as the site of αIIbβ3 overlaps the binding site of ristocetin and 6G1, both which induce VWF to bind GP Ibα. Therefore, by binding to the same site as 6G1 and ristocetin in the C-terminal peptide of A1, αIIbβ3 may regulate the affinity of A1 for GP Ibα in flowing blood.

Endotoxin enhances microvascular thrombosis in mouse cremaster venules via a TLR4-dependent, neutrophil-independent mechanism

2006 ◽  
Vol 290 (4) ◽  
pp. H1671-H1679 ◽  
Author(s):  
Rolando E. Rumbaut ◽  
Ricardo V. Bellera ◽  
Jaspreet K. Randhawa ◽  
Corie N. Shrimpton ◽  
Swapan K. Dasgupta ◽  
...  
Keyword(s):  
Platelet Aggregation ◽  
Platelet Adhesion ◽  
Ex Vivo ◽  
Thrombus Formation ◽  
Mouse Strains ◽  
Microvascular Endothelium ◽  
Microvascular Thrombosis ◽  
Platelet Thrombus ◽  
Adhesive Interactions

Endotoxemia promotes adhesive interactions between platelets and microvascular endothelium in vivo. We sought to determine whether endotoxin (lipopolysaccharide, LPS) modified platelet thrombus formation in mouse cremaster venules and whether Toll-like receptor 4 (TLR4) and neutrophils were involved in the response. Intravital videomicroscopy was performed in the cremaster microcirculation of pentobarbital-anesthetized mice; venular platelet thrombi were induced with a light/dye endothelial injury model. C57BL/6 mice treated with Escherichia coli endotoxin had enhanced rates of venular platelet thrombus formation: the time to microvessel occlusion was reduced by ∼50% ( P < 0.005) compared with saline-treated animals. Enhanced microvascular thrombosis was evident as early as 2 h after LPS administration. LPS had no effect on thrombosis in either of two mouse strains with altered TLR4 signaling (C57BL/10ScNJ or C3H/HeJ), whereas it enhanced thrombosis in the control strains (C57BL/10J and C3H/HeN). LPS also enhanced platelet adhesion to endothelium in the absence of light/dye injury. Platelet adhesion, but not enhanced thrombosis, was inhibited by depletion of circulating neutrophils. LPS failed to enhance platelet aggregation ex vivo and did not influence platelet P-selectin expression, a marker of platelet activation. These findings support the notion that endotoxemia promotes platelet thrombus formation independent of neutrophils and without enhancement of platelet aggregation, via a TLR4-dependent mechanism.

Enzymatic Removal of ADP from Plasma: Unaltered Platelet Adhesion but Reduced Aggregation on Subendothelium and Collagen Fibrils

1976 ◽  
Vol 35 (02) ◽  
pp. 334-341 ◽  
Author(s):  
Th B. Tschopp ◽  
H.R Baumgartner
Keyword(s):  
Platelet Adhesion ◽  
Thrombus Formation ◽  
Rabbit Aorta ◽  
Creatine Phosphate ◽  
Collagen Fibrils ◽  
Arterial Blood Flow ◽  
Subsequent Formation ◽  
Arterial Blood ◽  
Enzyme Combination ◽  
Platelet Thrombus

SummarySubendothelium of rabbit aorta and fibrillar collagen were exposed to citrated human or rabbit blood which was circulated through a perfusion chamber under flow conditions similar to those found in arteries. The resulting platelet adhesion and subsequent formation of platelet micro thrombi on the exposed surfaces were measured in 0.8 μm thick sections by a morphometry technique using light microscopy.Removal of plasma ADP by the substrate-enzyme combination CP-CPK (creatine phosphate-creatine phosphokinase; 3 mM and 90 U/ml blood) did not affect the initial attachment and spreading of platelets on subendothelium, whereas platelet thrombus formation was strongly inhibited. On free collagen fibrils CP-CPK was much less inhibitory on platelet thrombus formation but platelet adhesion again was not affected. It is concluded that platelet aggregation induced by thrombogenic surfaces in the presence of arterial blood flow is at least partially governed by ADP released from adhering platelets. Platelet adhesion to the examined surfaces, however, does not seem to be mediated by plasma ADP.

Just a Drop of Blood: Exploration of Shear-Dependent Platelet Adhesion and Activation in Microfluidic Devices.

Blood ◽  
2007 ◽  
Vol 110 (11) ◽  
pp. 3650-3650 ◽  
Author(s):  
Ana Kasirer-Friede ◽  
Edgar Gutierrez ◽  
Brian Petrich ◽  
Sanford J. Shattil ◽  
Mark H. Ginsberg ◽  
...  
Keyword(s):  
Shear Rate ◽  
Shear Flow ◽  
Blood Sample ◽  
Platelet Adhesion ◽  
Thrombus Formation ◽  
Microfluidic Devices ◽  
Extracellular Matrices ◽  
Wild Type ◽  
Shear Rates ◽  
Platelet Thrombus

Abstract Interactions of platelets and their adhesion receptors with extracellular matrices are essential for hemostasis. Platelets experience different shear rates as they circulate through the vasculature. Conventional studies of platelets in shear flow are performed in simple flow chambers with relatively large volumes of cells and reagents, limiting testing when these are in short supply. Microfluidics technology should enable the concurrent study of multiple small volume samples across a wide range of shear rates, thereby allowing trends to emerge that might be difficult to detect otherwise. To achieve this goal, we fabricated PDMS microfluidic devices that permit testing of dynamic platelet adhesion over a 100-fold span of shear rates from a single 200μl blood sample. Alternate device design permits synchronous monitoring of platelet adhesion from two genetically distinct blood samples or treatment groups. We have used this technology to gain new insights into integrin αIIbβ3 function in mepacrine-labeled platelets under shear flow. In whole blood, the adhesion of wild-type mouse platelets to a fibrinogen-coated substrate was shear rate-dependent, similarly to human platelets. In contrast, adhesion of αIIbβ3-deficient (β3−/−) platelets was virtually absent above a shear rate of 100 s−1. To distinguish between requirements for the presence of an intact extracellular αIIbβ3 ligand binding domain versus an intact integrin activation process, we used mice with a Y/A mutation at residue 747 in the β3 cytoplasmic tail (β3Y747A), that selectively blocks talin interaction with β3, agonist-induced αIIbβ3 activation, and platelet thrombus formation in vivo. When compared to wild-type and β3−/− platelets, a normal αIIbβ3 extracellular domain on β3Y747A platelets partially rescued dynamic adhesion to fibrinogen by 50–80% at ≤130 s−1, but by only 25% at 250 s−1. Treatment of wild-type platelets with PGE1 to inhibit platelet activation similarly reduced adhesion to fibrinogen at higher shear rates. On fibrillar type I collagen, wild-type platelets formed an initial monolayer and progressively larger thrombi over time. In addition, platelets supported rolling and firm adhesion of granulocytes in a manner dependent on shear rate, platelet P-selectin and granulocyte PSGL1. In contrast, no platelet thrombus growth on collagen was observed with αIIbβ3-deficient or β3Y747A platelets, or with wild-type platelets treated with PGE1. Furthermore, even the initial adhesion of αIIbβ3-deficient and β3Y747A platelets to collagen rapidly declined at increasing shear rates (120%, 30% and 7% of wild-type platelets at 70, 1000 and 4000 s−1, respectively (p &lt; 0.01)). Taken together, these studies establish that microfluidics provides an efficient and high-throughput platform to study mechanisms of dynamic platelet adhesion, activation and thrombus formation on extracellular matrices. Furthermore, they demonstrate a role for talin-dependent αIIbβ3 activation in all of these processes. This platform will be particularly useful under conditions where blood sample volumes or reagents are limiting, such as in neonates, and genetically-modified model organisms.

FIBRONECTIN IS REQUIRED FOR PLATELET ADHESION AND FOR THROMBUS FORMATION ON SUBENDOTHELIUM AND COLLAGEN SURFACES

1987 ◽  
Author(s):  
E Bastida ◽  
G Escolar ◽  
R Castillo ◽  
A Ordinas ◽  
J J Sixma
Keyword(s):  
Platelet Adhesion ◽  
Thrombus Formation ◽  
Fibrillar Collagen ◽  
Flow Conditions ◽  
Shear Rates ◽  
Human Collagen ◽  
Platelet Thrombus ◽  
Computerized System ◽  
Total Coverage

Fibronectin (FN) plays a role in several adhesion mediated functions including the interaction of platelets with subendothelium.We investigated the role of plasma FN in platelet adhesion and platelet thrombus formation under flow conditions.To do this we used two different perfusion models:1)the annular chamber with α -chymotrypsin-treated rabbit vessel segments and 2)the flat chamber with coverslips coated with fibrillar purified human collagen type III.Perfusates consisted of washed platelets, and washed red blood celIs,suspended in normal or FN-depleted plasma.Perfusions were carried out for 10 min at shear rates of 300 or 1300 sec™1 Platelet deposition and thrombus dimensions were morphometrically evaluated by a computerized system. We found that depletion of plasma FN significantly reduced the percentage of total coverage surface and percentage of platelet thrombus, at both shear rates studied, and in both perfusion systems (p < 0.01)(p < 0.01).The dimensions of the platelet thrombi formed in perfusions at high shear rate were also significantly reduced in perfusions carried out with FN-depleted plasma.(p < 0.01). Addition of purified FN to FN-depleted perfusates restored all the values to those measured in the control perfusions.These results indicate that, in addition to supporting platelet adhesion to the subendothelium and to fibrillar collagen, FN contributes to platelet thrombus formation under flow conditions.

Fibronectin inhibition of platelet thrombus formation in an in vivo porcine model of vascular injury

1994 ◽  
Vol 76 (4) ◽  
pp. 343-351 ◽  
Author(s):  
Dudley G. Moon ◽  
Brian M. Matayoshi ◽  
Lisa K. Weston ◽  
Fred L. Minnear ◽  
John E. Kaplan
Keyword(s):  
Vascular Injury ◽  
Porcine Model ◽  
Thrombus Formation ◽  
Platelet Thrombus

scholarly journals Fibronectin is required for platelet adhesion and for thrombus formation on subendothelium and collagen surfaces

Blood ◽  
1987 ◽  
Vol 70 (5) ◽  
pp. 1437-1442 ◽  
Author(s):  
E Bastida ◽  
G Escolar ◽  
A Ordinas ◽  
JJ Sixma
Keyword(s):  
Platelet Adhesion ◽  
Thrombus Formation ◽  
Flow Conditions ◽  
Shear Rates ◽  
Platelet Aggregate ◽  
Human Collagen ◽  
Platelet Thrombus ◽  
Computerized System ◽  
Total Coverage

Abstract Fibronectin (FN) plays a role in several adhesion mediated functions including the interaction of platelets with subendothelium. We investigated the role of plasma FN in platelet adhesion and platelet thrombus formation under flow conditions. We used two different perfusion models: the annular chamber with alpha-chymotrypsin-treated rabbit vessel segments, and the flat chamber with coverslips coated with fibrillar purified human collagen type III. Perfusates consisted of washed platelets and washed RBCs, suspended in normal or FN-depleted plasma. Perfusions were carried out for ten minutes at shear rates of 300 or 1,300 s-1. Platelet deposition and thrombus dimensions were evaluated morphometrically by a computerized system. We found that depletion of plasma fibronectin significantly reduced the percentage of total coverage surface and percentage of platelet thrombus, at both shear rates studied, and in both perfusion systems (P less than .01) (P less than .01). The dimensions of the platelet thrombi formed in perfusions at high shear rate were also significantly reduced in perfusions carried out with FN depleted plasma (P less than .01). Addition of purified FN to FN-depleted perfusates restored all values to those measured in the control perfusions. These results indicate that plasma FN is required for platelet aggregate and thrombus formation following adhesion under flow conditions.

Increased Platelet Thrombus Formation Under Flow Condition In Myeloproliferative Neoplasms (MPN)

Blood ◽  
2013 ◽  
Vol 122 (21) ◽  
pp. 33-33
Author(s):  
Alfonso Vignoli ◽  
Paola van der Meijden ◽  
Marina Marchetti ◽  
Cinzia Giaccherini ◽  
Serena Tessarolo ◽  
...  
Keyword(s):  
Platelet Adhesion ◽  
Thrombus Formation ◽  
Annexin V ◽  
Fluorescence Microscope ◽  
Control Group ◽  
Flow Conditions ◽  
Jak2 Mutation ◽  
Platelet Surface ◽  
Thrombotic Risk ◽  
Platelet Thrombus

Abstract Background Essential Thrombocythemia (ET) and Polycythemia Vera (PV) are MPNs characterized by a high incidence of both arterial and venous thrombosis, and microcirculatory disturbances. Platelet abnormalities have been variably involved in the thrombotic diathesis of these patients, without providing conclusive evidence. Remarkably, no studies have explored so far the MPN platelet thrombus formation capacity underflow conditions. Aim In order to evaluate whether and to what extent the MPN platelet membrane abnormalities may influence their interactions with the vessel wall components in a dynamic system, we wanted to characterize the ET and PV platelet adhesion capacity under flow conditions, by using an in vitro system based on a parallel flow chamber connected to the EVOS fluorescence microscope. The effects of the V617F JAK2 mutational status, cytoreductive therapy, and circulating von Willebrand Factor (vWF) on platelet adhesion in this system were also explored. Methods Nine ET (3M/6F; age 63 years, range 60-81) and 6 PV (3M/4F; age 74 years, range 58-82) patients were enrolled into the study upon informed consent. Eleven healthy subjects (5M/6F; age 44 years, range 35-55) acted as a control group (CTR). Peripheral venous whole blood was withdrawn in sodium citrate, recalcified in the presence of heparin, and perfused over a collagen-coated surface for 4 min at a shear rate of 1000 s-1. Platelets were then stained with an anti-CD62P (P-selectin)-FITC antibody as a platelet activation index, and annexin V-AlexaFluor647 as a measure of the procoagulant phosphatidylserine (PS) expression. After staining, images of adherent platelets in random fields were taken using phase contrast and fluorescence imaging with the EVOS fluorescence microscope system. Results were the mean±SD of the percentage of area covered by all platelets, or as the % of adherent platelets positive to either P-selectin or annexin V. In parallel, plasma vWF antigen and activity levels were measured by ELISA. Statistical analysis was performed by SPSS software package. Results Platelet adhesion was significantly greater (p<0.05) in both ET (49.3±14.5%) and PV patients (55.3±12.7%) compared to controls (31.6±7.3%). Among patients, platelet adhesion was significantly (p<0.05) increased in those positive for the V617F JAK2 mutation compared to the negative ones, with the highest values in the homozygous subjects. Patients on hydroxyurea (HU) therapy (n=7) had significantly lower platelet adhesion (45.2±13.0%) compared to non-HU-treated patients (56.9±10.4%; p<0.05).The % platelet adhesion directly related to either platelet (r=0.623, p=0.001) and leukocyte (r=0.506, p<0.01) counts, but not to plasma vWF levels. Multivariate regression analysis adjusted for age, sex, and HU therapy, confirmed platelet count and V617F JAK2 mutation as significant determinants of platelet adhesion. Although adhesion was increased, the platelet surface expression of P-selectin and PS was reduced in ET (P-sel: 70±11% pos. platelets; PS: 11±6% pos. platelets) and PV (P-sel: 66±13%; PS: 9±5%) patients compared to controls (P-sel: 74±8%; PS: 20±8%). Conclusions The data show for the first time, in MPN patients, an increased platelet adhesion capacity to collagen under flow conditions, indicating a greater thrombus formation potential. This phenomenon is likely not related to the expression of membrane P-selectin and phosphatidylserine, but is significantly influenced by the V617F JAK2 mutation burden and is sensitive to the cytoreductive treatment with HU. Prospective studies are worth to establish the role of the EVOS assay in assessing the levels of thrombotic risk in MPN patients. Disclosures: No relevant conflicts of interest to declare.

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