Absence of Fibrinogen in Afibrinogenemia Results in Large but Loosely Packed Thrombi under Flow Conditions

2001 ◽  
Vol 85 (04) ◽  
pp. 736-742 ◽  
Author(s):  
Ya-Ping Wu ◽  
Martin IJsseldijk ◽  
Jaap Zwaginga ◽  
Jan Sixma ◽  
Philip de Groot ◽  
...  

SummaryWe studied the role of fibrinogen in platelet thrombus formation under flow on adhesive proteins using afibrinogenemic blood (LMWH anticoagulated) in a perfusion system. Perfusions with afibrinogenemic blood showed strong increased surface coverage and thrombus volume that normalized upon addition of fibrinogen. Similar studies using citrate anticoagulated blood showed that this was due to fibrinogen and not fibrin. Morphological analysis showed that afibrinogenemic thrombi were loosely packed and consisted mainly of dendritic platelets that contacted one another through filopodia. However, in the presence of fibrinogen, platelets formed lamellipodia and spread out on top of one another. Studies with radiolabeled platelets showed similar numbers of platelets in both conditions demonstrating that the difference is one of packing and the larger size is due to absence of lamellipodia formation and spreading. The found increased thrombus size and loosely packed platelets might help to understand thrombotic complications sometimes seen in afibrinogenemia patients.

1987 ◽  
Author(s):  
E Bastida ◽  
G Escolar ◽  
R Castillo ◽  
A Ordinas ◽  
J J Sixma

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.


Blood ◽  
1987 ◽  
Vol 70 (5) ◽  
pp. 1437-1442 ◽  
Author(s):  
E Bastida ◽  
G Escolar ◽  
A Ordinas ◽  
JJ Sixma

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.


Blood ◽  
1987 ◽  
Vol 70 (5) ◽  
pp. 1437-1442
Author(s):  
E Bastida ◽  
G Escolar ◽  
A Ordinas ◽  
JJ Sixma

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.


Blood ◽  
1998 ◽  
Vol 92 (5) ◽  
pp. 1518-1525 ◽  
Author(s):  
Jean-Pierre Bossavy ◽  
Claire Thalamas ◽  
Luc Sagnard ◽  
André Barret ◽  
Kjell Sakariassen ◽  
...  

Abstract No randomized study comparing the effect of combined ticlopidine and aspirin therapy versus each drug alone in reducing poststenting thrombotic complications has been performed. To compare these three antiplatelet regimens versus placebo, we conducted a double-blind randomized study using an ex vivo model of thrombosis. Sixteen healthy male volunteers were assigned to receive for 8 days the following four regimens separated by a 1-month period: aspirin 325 mg/d, ticlopidine 500 mg/d, aspirin 325 mg/d + ticlopidine 500 mg/d, and placebo. At the end of each treatment period, native nonanticoagulated blood was drawn directly from an antecubital vein over collagen- or tissue factor (TF)-coated coverslips positioned in a parallel-plate perfusion chamber at an arterial wall shear rate (2,600 s−1 ) for 3 minutes. Thrombus, which formed on collagen in volunteers treated by placebo, were rich in platelets and poor in fibrin. As compared with placebo, aspirin and ticlopidine alone reduced platelet thrombus formation by only 29% and 15%, respectively (P &gt; .2). In contrast, platelet thrombus formation was blocked by more than 90% in volunteers treated by aspirin + ticlopidine (P &lt; .01v placebo or each treatment alone). Furthermore, the effect of the drug combination therapy was significantly larger than the sum of the two active treatments (P &lt; .05). Thrombus, which formed on TF-coated coverslips in volunteers treated by placebo, were rich in fibrin and platelets. Neither of the three antiplatelet treatments significantly inhibited fibrin deposition and platelet thrombus formation on this surface (P &gt; .2). Thus, the present study shows that combined aspirin and ticlopidine therapy dramatically potentiates the antithrombotic effect of each drug alone, but that the antithrombotic effect of the combined treatment depends on the nature of the thrombogenic surface. © 1998 by The American Society of Hematology.


Blood ◽  
2008 ◽  
Vol 112 (11) ◽  
pp. 3932-3932
Author(s):  
Ivo Cornelissen ◽  
Erica De Candia ◽  
Shaun R Coughlin

Abstract Following vascular injury, platelets are recruited and activated by adhesive proteins exposed on the subendothelium (including collagen), released agonists and locally generated thrombin. In mice, protease activated receptor 4 (PAR-4) mediates the platelet signaling response to thrombin. Previous studies showed that platelets from PAR-4 null mice do not respond to thrombin and while platelet thrombi do form at the site of injury in PAR-4 deficient animals, they do not propagate and extend into the lumen like thrombi in wild-type mice. The activation pathway responsible for this juxtamural platelet accumulation remains unknown. The collagen exposed on the subendothelium activates and recruites platelets at the site of injury by interacting with membrane glycoprotein (GP) VI. Therefore, the collagen-GP-VI pathway is a putative candidate for the platelet thrombus formation near the vessel wall. Using hirudin as a thrombin inhibitor in mice with disrupted GP-VI expression, it has been previously shown that GP-VI signaling and thrombin activation pathways may cooperate during thrombus growth. To more precisely evaluate the interplay between the thrombin/PAR-4 and collagen/GP-VI signaling pathways, we crossed mice lacking PAR-4 and GP-VI, and subsequently compared bleeding time and arterial thrombus formation in PAR-4:GP-VI double or single deficient animals. All genetic combinations were born at the expected mendelian distribution. Double deficient females carried offspring to term and no bleeding was observed during parturition. Pups lacking both receptors demonstrated transient perinatal abdominal bleeding which resolved rapidly. However, we observed prolonged tail bleeding times in double deficient animals compared to their single deficient littermates. Furthermore in a FeCl3-induced carotid thrombosis model, mice lacking both receptors were completely protected compared to their littermates. This study suggests that there is an interaction between the thrombin and collagen activating pathways in the setting of hemostasis and thrombosis. Figure Figure Figure Figure


Blood ◽  
1998 ◽  
Vol 92 (5) ◽  
pp. 1518-1525 ◽  
Author(s):  
Jean-Pierre Bossavy ◽  
Claire Thalamas ◽  
Luc Sagnard ◽  
André Barret ◽  
Kjell Sakariassen ◽  
...  

No randomized study comparing the effect of combined ticlopidine and aspirin therapy versus each drug alone in reducing poststenting thrombotic complications has been performed. To compare these three antiplatelet regimens versus placebo, we conducted a double-blind randomized study using an ex vivo model of thrombosis. Sixteen healthy male volunteers were assigned to receive for 8 days the following four regimens separated by a 1-month period: aspirin 325 mg/d, ticlopidine 500 mg/d, aspirin 325 mg/d + ticlopidine 500 mg/d, and placebo. At the end of each treatment period, native nonanticoagulated blood was drawn directly from an antecubital vein over collagen- or tissue factor (TF)-coated coverslips positioned in a parallel-plate perfusion chamber at an arterial wall shear rate (2,600 s−1 ) for 3 minutes. Thrombus, which formed on collagen in volunteers treated by placebo, were rich in platelets and poor in fibrin. As compared with placebo, aspirin and ticlopidine alone reduced platelet thrombus formation by only 29% and 15%, respectively (P > .2). In contrast, platelet thrombus formation was blocked by more than 90% in volunteers treated by aspirin + ticlopidine (P < .01v placebo or each treatment alone). Furthermore, the effect of the drug combination therapy was significantly larger than the sum of the two active treatments (P < .05). Thrombus, which formed on TF-coated coverslips in volunteers treated by placebo, were rich in fibrin and platelets. Neither of the three antiplatelet treatments significantly inhibited fibrin deposition and platelet thrombus formation on this surface (P > .2). Thus, the present study shows that combined aspirin and ticlopidine therapy dramatically potentiates the antithrombotic effect of each drug alone, but that the antithrombotic effect of the combined treatment depends on the nature of the thrombogenic surface.© 1998 by The American Society of Hematology.


Blood ◽  
2011 ◽  
Vol 117 (4) ◽  
pp. 1408-1414 ◽  
Author(s):  
Zurina Romay-Penabad ◽  
Renan Aguilar-Valenzuela ◽  
Rolf T. Urbanus ◽  
Ronald H. W. M. Derksen ◽  
Maarten T. T. Pennings ◽  
...  

Abstract Antiphospholipid (aPL)/anti-β2 glycoprotein I (anti-β2GPI) antibodies stimulates tissue factor (TF) expression within vasculature and in blood cells, thereby leading to increased thrombosis. Several cellular receptors have been proposed to mediate these effects, but no convincing evidence for the involvement of a specific one has been provided. We investigated the role of Apolipoprotein E receptor 2 (ApoER2′) on the pathogenic effects of a patient-derived polyclonal aPL IgG preparation (IgG-APS), a murine anti-β2GPI monoclonal antibody (E7) and of a constructed dimeric β2GPI I (dimer), which in vitro mimics β2GPI-antibody immune complexes, using an animal model of thrombosis, and ApoER2-deficient (−/−) mice. In wild type mice, IgG-APS, E7 and the dimer increased thrombus formation, carotid artery TF activity as well as peritoneal macrophage TF activity/expression. Those pathogenic effects were significantly reduced in ApoER2 (−/−) mice. In addition, those effects induced by the IgG-APS, by E7 and by the dimer were inhibited by treatment of wild-type mice with soluble binding domain 1 of ApoER2 (sBD1). Altogether these data show that ApoER2 is involved in pathogenesis of antiphospholipids antibodies.


Blood ◽  
2014 ◽  
Vol 124 (21) ◽  
pp. 1483-1483
Author(s):  
Yasuaki Shida ◽  
Keiji Nogami ◽  
Hiroaki Minami ◽  
Hiroaki Yaoi ◽  
Tomoko Matsumoto ◽  
...  

Abstract Background Factor VIII (FVIII) is an essential factor for coagulation system in the intrinsic pathway. Due to the short survival of FVIII in the plasma circulation, it requires von Willebrand factor (VWF) as a carrier protein to maintain the optimal level for hemostasis. VWF also plays an important role in primary hemostasis by bridging platelets to exposed subendothelial collagens, especially under high shear flow environment. Since VWF carries FVIII, it is conceivable that VWF takes FVIII to the sites of vascular injury. However, the role of FVIII at the local sites under flow conditions is not fully understood despite of the fact that increased level of FVIII is associated with the risk of venous thrombosis and the deficiency of FVIII is the pathology of the bleeding disorder, hemophilia A. The treatment of hemophilia A largely depends on the infusion of FVIII concentrates, which is often complicated by the development of the inhibitor. Recently, bispecific antibody(ACE910)that mimics the role of FVIIIa by recognizing FIXa and FX has been developed and is currently under clinical trial. This antibody theoretically works regardless of the presence of devastating inhibitors against FVIII. Furthermore, it could also improve the clinical outcome of the other bleeding disorders, such as von Willebrand disease (VWD). Aim To analyze the role of FVIII and VWF, and impact of ACE910 at the sites of vascular injury under various shear conditions, we have developed the flow-mediated thrombosis model using flow chamber system. Method Whole blood obtained from healthy donors, hemophilia A and VWD patients were perfused into the collagen coated flow chamber under high (2,500s-1) or low shear (50s-1) flow conditions with/without FVIII concentrate, FVIII/VWF concentrate and ACE910. Formed thrombus was fixed and immunostaining was performed with phalloidin (Platelet), anti-FVIII antibody (FVIII) and anti-thrombin antibody (Thrombin). For the detection of ACE910, anti-human IgG or anti-ACE antibody (rAQ8 or rAJ540) were used. Size of thrombi and distribution of platelet, FVIII, thrombin and ACE910 were analyzed. Result 1) Under high shear flow, thrombus formation of VWD blood was significantly impaired while blood from Hemophilia A demonstrated nearly normal thrombus formation. Addition of FVIII/VWF but not FVIII concentrate to the blood of these patients rescued the impaired thrombus formation. ACE910 enhanced the thrombus formation of blood from both VWD and hemophilia A. Under low shear flow, blood from both hemophilia A and VWD demonstrated decreased thrombus formation. FVIII, FVIII/VWF concentrates and ACE910 improved the size of thrombus. 2) Localization of FVIII was evaluated with thrombin as a marker for the activation of coagulation. Platelets and thrombin demonstrated complete co-localization and intensity of thrombin staining was associated with thrombus size. VWF localized mainly outer layer of thrombus and FVIII localized in and around thrombus. At high shear condition, FVIII and VWF mostly existed with platelets. By contrast, FVIII and VWF demonstrated less co-localization with platelets under low shear condition. ACE910 demonstrated similar tendency to FVIII localization although ACE910 did not appear around thrombus. Conclusion We have developed the flow chamber system to evaluate the extent of thrombogenesis under various shear environment. VWF showed dominant role under high shear conditions while FVIII plays a key role under low shear conditions. FVIII, VWF and ACE910 demonstrated distinct localization. Interestingly, the distribution of FVIII was broader than VWF and platelet. FVIII localized to platelets presumably prior to its activation and contributed for the subsequent thrombin generation at local sites. Finally, ACE910 demonstrated consistent enhancement of thrombus formation of blood from both hemophilia A and VWD and, therefore, is prompted for the treatment of these bleeding disorders. Disclosures Shida: Chugai Pharmaceutical Co., Ltd.: Research Funding. Nogami:Chugai Pharmaceutical Co., Ltd.: Membership on an entity's Board of Directors or advisory committees, Research Funding. Minami:Chugai Pharmaceutical Co., Ltd.: Research Funding. Yaoi:Chugai Pharmaceutical Co., Ltd.: Research Funding. Matsumoto:Chugai Pharmaceutical Co., Ltd.: Research Funding. Kitazawa:Chugai Pharmaceutical Co., Ltd.: Employment, Equity Ownership, Patents & Royalties. Hattori:Chugai Pharmaceutical Co., Ltd.: Employment, Equity Ownership, Patents & Royalties. Shima:Chugai Pharmaceutical Co., Ltd.: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding.


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