Analysing responses to aspirin and clopidogrel by measuring platelet thrombus formation under arterial flow conditions

2013 ◽  
Vol 109 (01) ◽  
pp. 102-111 ◽  
Author(s):  
Kazuya Hosokawa ◽  
Tomoko Ohnishi ◽  
Hisayo Sameshima ◽  
Naoki Miura ◽  
Takashi Ito ◽  
...  
Keyword(s):  
Platelet Aggregation ◽  
Antiplatelet Therapy ◽  
Dual Antiplatelet Therapy ◽  
Thrombus Formation ◽  
Healthy Controls ◽  
Vascular Events ◽  
Shear Rates ◽  
Platelet Thrombus ◽  
Flow Pressure ◽  
Induced Aggregation

SummaryHigh residual platelet aggregability and circulating platelet-monocyte aggregates in patients administered aspirin and clopidogrel are associated with ischaemic vascular events. To determine the relevance of these factors with residual thrombogenicity, we measured platelet thrombus formation using a microchip-based flow-chamber system in cardiac patients receiving aspirin and/or clopidogrel, and evaluated its correlation with agonist-inducible platelet aggregation and platelet-monocyte aggregates. Platelet thrombus formation was analysed by measuring flow pressure changes due to the occlusion of micro-capillaries and was quantified by calculating AUC10 (area under the flow pressure curve). The growth and stability of platelet thrombi that formed inside microchips at shear rates of 1000, 1500, and 2000 s-1 were markedly reduced in patients receiving aspirin and/or thienopyridine compared to healthy controls (n=33). AUC10 values of aspirin therapy patients (n=20) were significantly lower and higher than those of healthy controls and dual antiplatelet therapy patients (n=19), respectively, and showed relatively good correlations with collagen-induced platelet aggregation and platelet-monocyte aggregates at 1000 and 1500 s-1 (r s >0.59, p<0.01). In contrast, AUC10 in dual antiplatelet therapy patients was significantly correlated with ADP-induced platelet aggregation at all examined shear rates (r s >0.59, p<0.01), but did not correlate with collagen-induced aggregation. Aspirin monotherapy patients with high residual platelet thrombogenicity also exhibited significant elevations in both collagen-induced platelet aggregation and platelet-monocyte aggregates. Our results, although preliminary, suggest that residual platelet thrombogenicity in aspirin-treated patients is associated with either collagen-induced platelet aggregation or circulating platelet-monocyte aggregates, but it is predominantly dependent on ADP-induced platelet aggregation in patients receiving dual antiplatelet therapy.

Abstract W P114: Assessment of Platelet Thrombus Formation in Patients with Carotid Disease Administered Clopidogrel

Stroke ◽  
2014 ◽  
Vol 45 (suppl_1) ◽  
Author(s):  
Masako Yamazaki ◽  
Tomoko Ohnishi ◽  
Kazuya Hosokawa ◽  
Yoshikazu Okada ◽  
Akitsugu Kawashima ◽  
...  
Keyword(s):  
Ischemic Stroke ◽  
Platelet Aggregation ◽  
Carotid Stenosis ◽  
Platelet Function ◽  
Thrombus Formation ◽  
The Other ◽  
Flow Conditions ◽  
Carotid Disease ◽  
Platelet Thrombus ◽  
Flow Pressure

Background: Many studies have demonstrated that high residual platelet function in patients administered clopidogrel is associated with cardiovascular events, although, the majority of those studies examined the patients with coronary artery disease. We studied platelet function in patients with ischemic stroke treated by clopidogrel, and compared residual platelet function according to the severity of carotid disease. Methods: We measured platelet aggregation induced by ADP, VerifyNow P2Y12 assay (PRU), phosphorylation of vasodilator-stimulated phosphoprotein (PRI), platelet-leukocyte complex (PLC), and platelet p-selectin expression (PS) in 30 patients with ischemic stroke administered clopidogrel (21 males and 9 females, mean age was 65 years). We also measured platelet thrombus formation under arterial flow conditions using newly developed microchip-based flow chamber system. In this system, platelet thrombus formation was analyzed by measuring flow pressure changes due to occlusion of microchip and was quantified by calculating area under the flow pressure curve (AUC). Each marker was compared between patients with severe carotid stenosis (15 cases) and those with mild to moderate carotid stenosis (15 cases). Results: Platelet function tests such as percentages of platelet aggregation induced by ADP, PRU, PRI, and PS was not significantly different between different severities of carotid stenosis. On the other hand, AUC values and PLC of patients with severe major carotid stenosis were significantly higher than those with mild to moderate stenosis. Conclusions: These results suggested that clopidogrel inhibits platelet aggregation irrespective of the severity of carotid stenosis. On the other hand, platelet thrombus formation under arterial flow conditions and platelet leukocyte interactions were higher in patients with severe carotid stenosis than those with mild to moderate stenosis.

scholarly journals Relative antithrombotic effects of monoclonal antibodies targeting different platelet glycoprotein-adhesive molecule interactions in nonhuman primates

Blood ◽  
1994 ◽  
Vol 83 (11) ◽  
pp. 3218-3224 ◽  
Author(s):  
Y Cadroy ◽  
SR Hanson ◽  
AB Kelly ◽  
UM Marzec ◽  
BL Evatt ◽  
...  
Keyword(s):  
Platelet Aggregation ◽  
Ex Vivo ◽  
Thrombus Formation ◽  
Platelet Glycoprotein ◽  
Venous Flow ◽  
Shear Rates ◽  
Platelet Deposition ◽  
Antithrombotic Effects ◽  
Induced Aggregation

Abstract The relative antithrombotic effectiveness of targeting glycoprotein (GP) Ib-dependent versus GPIIb-IIIa-dependent platelet interactions has been determined in baboons by measuring thrombus formation after infusing comparable antihemostatic doses of anti-von Willebrand factor (vWF) monoclonal antibody (MoAb) BB3-BD5, anti-GPIb MoAb AP1, and anti- GPIIb-IIIa MoAb LJ-CP8 under conditions of arterial and venous flow (shear rates of 750 to 1,000 seconds-1 and 100 seconds-1, respectively). Thrombus formation was quantified as 111In-platelet deposition and 125I-fibrin accumulation on segments of collagen-coated tubing interposed in chronic exteriorized arteriovenous (AV) shunts for 40 minutes. In vitro, anti-vWF MoAb BB3 BD5 (IgG) and anti-GPIb MoAb AP1 [IgG or F(ab)2 fragments] inhibited ristocetin-induced platelet aggregation (IC50 50 nmol/L and 1 mumol/L, respectively), but neither of these MoAbs blocked platelet aggregation induced by adenosine diphosphate (ADP) (P > .5). Conversely, anti-GPIIb-IIIa MoAb LJ-CP8 inhibited platelet aggregation induced by ADP (IC50 1 mumol/L, but failed to block ristocetin-induced platelet aggregation (P > .5). In vivo, the intravenous infusion of anti-vWF MoAb BB3 BD5 or anti-GPIIb- IIIa MoAb LJ-CP8 into baboons at doses that abolished corresponding agonist-induced aggregation ex vivo (bolus injections of 0.5 mg/kg and 10 mg/kg, respectively) prolonged template bleeding times from baseline values of 4.0 +/- 0.3 minutes to > 27 +/- 4 minutes, and to > 26 +/- 4 minutes, respectively (P 3 .001 in both cases), without affecting the peripheral platelet count (P > .5). However, injection of anti-GPIb MoAb AP1 [10 mg/kg as IgG or 1 mg/kg as F(ab)2 fragments] produced immediate irreversible thrombocytopenia (< 40,000 platelets/microL). Anti-GPIIb-IIIa MoAb LJ-CP8 abolished platelet deposition and fibrin accumulation on collagen segments under both arterial and venous flow conditions (P < .01 in all cases), whereas MoAb BB3 BD5 produced minimal inhibition of platelet deposition and no decrease in fibrin accumulation at arterial shear rates and undetectable antithrombotic outcomes at low shear. Thus, inhibiting GPIIb-IIIa-dependent platelet recruitment abrogates both thrombus formation and platelet hemostatic function at both venous and arterial shear rates. By contrast, interfering with GPIb-vWF-dependent platelet interactions abolishes platelet hemostatic function without producing corresponding antithrombotic effects.

scholarly journals Relative antithrombotic effects of monoclonal antibodies targeting different platelet glycoprotein-adhesive molecule interactions in nonhuman primates

Blood ◽  
1994 ◽  
Vol 83 (11) ◽  
pp. 3218-3224 ◽  
Author(s):  
Y Cadroy ◽  
SR Hanson ◽  
AB Kelly ◽  
UM Marzec ◽  
BL Evatt ◽  
...  
Keyword(s):  
Platelet Aggregation ◽  
Ex Vivo ◽  
Thrombus Formation ◽  
Platelet Glycoprotein ◽  
Venous Flow ◽  
Shear Rates ◽  
Platelet Deposition ◽  
Antithrombotic Effects ◽  
Induced Aggregation

The relative antithrombotic effectiveness of targeting glycoprotein (GP) Ib-dependent versus GPIIb-IIIa-dependent platelet interactions has been determined in baboons by measuring thrombus formation after infusing comparable antihemostatic doses of anti-von Willebrand factor (vWF) monoclonal antibody (MoAb) BB3-BD5, anti-GPIb MoAb AP1, and anti- GPIIb-IIIa MoAb LJ-CP8 under conditions of arterial and venous flow (shear rates of 750 to 1,000 seconds-1 and 100 seconds-1, respectively). Thrombus formation was quantified as 111In-platelet deposition and 125I-fibrin accumulation on segments of collagen-coated tubing interposed in chronic exteriorized arteriovenous (AV) shunts for 40 minutes. In vitro, anti-vWF MoAb BB3 BD5 (IgG) and anti-GPIb MoAb AP1 [IgG or F(ab)2 fragments] inhibited ristocetin-induced platelet aggregation (IC50 50 nmol/L and 1 mumol/L, respectively), but neither of these MoAbs blocked platelet aggregation induced by adenosine diphosphate (ADP) (P > .5). Conversely, anti-GPIIb-IIIa MoAb LJ-CP8 inhibited platelet aggregation induced by ADP (IC50 1 mumol/L, but failed to block ristocetin-induced platelet aggregation (P > .5). In vivo, the intravenous infusion of anti-vWF MoAb BB3 BD5 or anti-GPIIb- IIIa MoAb LJ-CP8 into baboons at doses that abolished corresponding agonist-induced aggregation ex vivo (bolus injections of 0.5 mg/kg and 10 mg/kg, respectively) prolonged template bleeding times from baseline values of 4.0 +/- 0.3 minutes to > 27 +/- 4 minutes, and to > 26 +/- 4 minutes, respectively (P 3 .001 in both cases), without affecting the peripheral platelet count (P > .5). However, injection of anti-GPIb MoAb AP1 [10 mg/kg as IgG or 1 mg/kg as F(ab)2 fragments] produced immediate irreversible thrombocytopenia (< 40,000 platelets/microL). Anti-GPIIb-IIIa MoAb LJ-CP8 abolished platelet deposition and fibrin accumulation on collagen segments under both arterial and venous flow conditions (P < .01 in all cases), whereas MoAb BB3 BD5 produced minimal inhibition of platelet deposition and no decrease in fibrin accumulation at arterial shear rates and undetectable antithrombotic outcomes at low shear. Thus, inhibiting GPIIb-IIIa-dependent platelet recruitment abrogates both thrombus formation and platelet hemostatic function at both venous and arterial shear rates. By contrast, interfering with GPIb-vWF-dependent platelet interactions abolishes platelet hemostatic function without producing corresponding antithrombotic effects.

Platelet Reactivity in Patients with Coronary Stenting Treated with Dual Antiplatelet Therapy and after Withdrawal of Clopidogrel: Impact of Bioactive Titanium Stent versus Everolimus-coated Stent

2019 ◽  
pp. 65-82
Author(s):  
Amparo Hernandiz ◽  
Jose Luis Díez ◽  
Antonio Moscardo ◽  
Ana Latorre ◽  
Maria Dolores Domenech ◽  
...  
Keyword(s):  
Platelet Aggregation ◽  
Antiplatelet Therapy ◽  
Dual Antiplatelet Therapy ◽  
Platelet Reactivity ◽  
Coronary Intervention ◽  
Diabetic Patients ◽  
Platelet Response ◽  
One Year ◽  
Induced Aggregation ◽  
Bioactive Stent

Objective:To study platelet reactivity at different times while on dual antiplatelet therapy (DAPT) with aspirin (ASA) and clopidogrel in patients treated with bioactive stents (TITAN2®) or everolimus-coated stents (XIENCE V®) and one month afterclopidogrel cessation. Background: Coronary intervention damages the endothelium and causes platelet response leading to thrombotic occlusion, which is prevented with DAPT. Methods:We studied 20 patients with bioactive stent and stable ischemia (BAS-SI group); 31 patients with bioactive stent and acute coronary syndrome (BAS-ACS group) and 31 patients with stable ischemia and everolimus-coated stent (EVE group). DAPT was administered (ASA 100 mg/day and clopidogrel 75 mg/day) for one year in BAS-ACS and EVE groups and for 1 month in BAS-SI group. Platelet aggregation induced by different agonists and platelet recruitment were analyzed at different times of DAPT and 1 month after clopidogrel cessation. Results: After one month of DAPT, platelet aggregation showed no difference between groups; at 12 months of DAPT, the response to collagen and ADP increased in EVE group. Platelet recruitment at 1 month was higher in the BAS-ACS than the other groups; after 12 months, recruitment increased in the EVE group with respect to BASACS. Platelet aggregation and recruitment in diabetics were significantly higher in all situations than in non-diabetic patients. Clopidogrel withdrawal increased ADPinduced aggregation and collagen-induced aggregation and recruitment. Conclusion: Platelet reactivity in patients with DAPT varies with time, depending on the subset of patients, the type of the stent implanted and the time after implantation.

scholarly journals Antithrombotic effect of a monoclonal antibody to the platelet glycoprotein IIb/IIIa receptor in an experimental animal model

Blood ◽  
1986 ◽  
Vol 68 (3) ◽  
pp. 783-786 ◽  
Author(s):  
BS Coller ◽  
JD Folts ◽  
LE Scudder ◽  
SR Smith
Keyword(s):  
Monoclonal Antibody ◽  
Animal Model ◽  
Platelet Aggregation ◽  
Ex Vivo ◽  
Thrombus Formation ◽  
Platelet Glycoprotein ◽  
Antithrombotic Effect ◽  
Antithrombotic Agent ◽  
Antithrombotic Effects ◽  
Platelet Thrombus

A murine monoclonal antibody directed at the platelet glycoprotein IIb/IIIa complex, which blocks platelet aggregation ex vivo, was tested for its antithrombotic effects in an established animal model of acute platelet thrombus formation in partially stenosed arteries. Infusion of 0.7 to 0.8 mg/kg of the F(ab')2 fragment of the antibody completely blocked new thrombus formation despite multiple provocations, making it the most potent antithrombotic agent tested in this model.

Supplemental Fibrinogen Restores Platelet Inhibitor-Induced Reduction in Thrombus Formation without Altering Platelet Function: An In Vitro Study

2020 ◽  
Vol 120 (11) ◽  
pp. 1548-1556
Author(s):  
Thomas Bärnthaler ◽  
Elisabeth Mahla ◽  
Gabor G. Toth ◽  
Rufina Schuligoi ◽  
Florian Prüller ◽  
...  
Keyword(s):  
Antiplatelet Therapy ◽  
Platelet Activation ◽  
Platelet Function ◽  
Dual Antiplatelet Therapy ◽  
Thrombus Formation ◽  
In Vitro Study ◽  
Coronary Intervention ◽  
Calcium Flux ◽  
Major Surgery

Abstract Background For patients treated with dual antiplatelet therapy, standardized drug-specific 3-to-7 day cessation is recommended prior to major surgery to reach sufficient platelet function recovery. Here we investigated the hypothesis that supplemental fibrinogen might mitigate the inhibitory effects of antiplatelet therapy. Methods and Results To this end blood from healthy donors was treated in vitro with platelet inhibitors, and in vitro thrombus formation and platelet activation were assessed. Ticagrelor, acetylsalicylic acid, the combination of both, and tirofiban all markedly attenuated the formation of adherent thrombi, when whole blood was perfused through collagen-coated microchannels at physiological shear rates. Addition of fibrinogen restored in vitro thrombus formation in the presence of antiplatelet drugs and heparin. However, platelet activation, as investigated in assays of P-selectin expression and calcium flux, was not altered by fibrinogen supplementation. Most importantly, fibrinogen was able to restore in vitro thrombogenesis in patients on maintenance dual antiplatelet therapy after percutaneous coronary intervention. Conclusion Thus, our in vitro data support the notion that supplementation of fibrinogen influences the perioperative hemostasis in patients undergoing surgery during antiplatelet therapy by promoting thrombogenesis without significantly interfering with platelet activation.

Lp-PLA2 and dual antiplatelet agents in intracranial arterial stenosis

Neurology ◽  
2019 ◽  
Vol 94 (2) ◽  
pp. e181-e189 ◽  
Author(s):  
Ming Yang ◽  
Anxin Wang ◽  
Jiejie Li ◽  
Xingquan Zhao ◽  
Liping Liu ◽  
...  
Keyword(s):  
High Risk ◽  
Antiplatelet Therapy ◽  
Proportional Hazards ◽  
Dual Antiplatelet Therapy ◽  
Cox Proportional Hazards ◽  
Arterial Stenosis ◽  
Minor Stroke ◽  
Activity Levels ◽  
Intracranial Arterial Stenosis ◽  
Vascular Events

ObjectiveTo evaluate the interaction effect of lipoprotein-associated phospholipase A2 (Lp-PLA2) activity on the efficacy and safety of dual/single antiplatelet therapy in patients with and without intracranial arterial stenosis (ICAS) by the Clopidogrel in High-Risk Patients with Acute Non-disabling Cerebrovascular Events trial.MethodsPatients with both MRI analysis and Lp-PLA2 testing results were included in the current subanalysis. The interaction of Lp-PLA2 activity with the effects of dual and single antiplatelet therapy were analyzed through Cox proportional hazards regressions model.ResultsAmong the 797 patients, the mean age was 63.1 ± 10.8 years, 518 (65%) were men, 356 (44.7%) had ICAS, and 441 (55.3%) did not. There were significantly more patients with elevated Lp-PLA2 activity in the ICAS group than in the non-ICAS group (43.8% vs 35.4%, p = 0.02). There was significant interaction between Lp-PLA2 activity levels and the 2 antiplatelet therapies for prevention of stroke recurrences and combined vascular events even after adjustment for confounding factors exclusively for patients with ICAS (p = 0.017, 0.017, respectively), but not for those without (p = 0.332, 0.674, respectively). Compared with aspirin alone, dual antiplatelet therapy significantly reduced the risk of stroke recurrences and combined vascular events (adjusted hazard ratio 0.33 [0.12–0.89], p = 0.028; 0.33 [0.12–0.89], p = 0.028, respectively) for patients with ICAS and nonelevated Lp-PLA2 activity.ConclusionsPresence of both ICAS and nonelevated Lp-PLA2 activity may predict better response to dual antiplatelet therapy in prevention of recurrent strokes and combined vascular events for patients with minor stroke or high-risk TIA.Clinicaltrials.gov identifierNCT00979589.

Ex vivo evaluation of anti-GPVI antibody in Cynomolgus monkeys: Dissociation between anti-platelet aggregatory effect and bleeding time

2006 ◽  
Vol 96 (08) ◽  
pp. 167-175 ◽  
Author(s):  
Yutaka Matsumoto ◽  
Hisao Takizawa ◽  
Kazuhiro Nakama ◽  
Xiaoqi Gong ◽  
Yoshihisa Yamada ◽  
...  
Keyword(s):  
Platelet Aggregation ◽  
Bleeding Time ◽  
Ex Vivo ◽  
Thrombus Formation ◽  
Inhibitory Effect ◽  
Bleeding Tendency ◽  
Fab Fragment ◽  
Dose Escalation Study ◽  
Cynomolgus Monkeys ◽  
Induced Aggregation

SummaryRecent progress in the understanding of thrombus formation has suggested an important role of glycoprotein (GP)VI. In contrast to its pivotal role in collagen-induced platelet activation, it has been suggested that its blockade does not induce massive bleeding tendency. To demonstrate the dissociation between inhibitory effect on platelet aggregation and bleeding by GPVI blockade, we examined the effects of Fab fragment of OM2, an anti-human GPVI monoclonal antibody on ex vivo collagen-induced platelet aggregation and skin bleeding time after intravenous injection in cynomolgus monkeys. In a dose-escalation study, OM2 potently (>80%) inhibited collagen-induced platelet aggregation at the cumulative dose of 0. 2 mg/kg with a slight prolongation of bleeding time (1. 3 times baseline value). Furthermore, at 18. 8 mg/kg, the highest dose tested, prolongation of bleeding time was still mild (1. 9 times). In contrast, abciximab, Fab fragment of anti-GPIIb/IIIa antibody prolonged bleeding time by 5. 0 times at 0. 35 mg/kg, the lowest effective dose on platelet aggregation. Ina pharmacodynamic study,a bolus injection of OM2 at 0. 4 mg/kg produced potent inhibition of collagen-induced aggregation up to six hours after injection, showing longer half-life than that of abciximab. The injection of OM2 Fab did not induce thrombocytopenia and GPVI depletion in monkeys. These results suggest that blockade of GPVI by antibody can exerta potent inhibitory effect on collagen-induced platelet aggregation with a milder prolongation of bleeding time than blockade of GPIIb/IIIa. This study indicates that OM2 has the potential to be developed as a new class of therapeutic tool.

Adrenergic receptor polymorphisms and platelet reactivity after treatment with dual antiplatelet therapy with aspirin and clopidogrel in acute coronary syndrome

2010 ◽  
Vol 103 (04) ◽  
pp. 774-779 ◽  
Author(s):  
Thomas Cuisset ◽  
Michalis Hamilos ◽  
Leen Delrue ◽  
Corinne Frere ◽  
Katia Verhamme ◽  
...  
Keyword(s):  
Acute Coronary Syndrome ◽  
Platelet Aggregation ◽  
Antiplatelet Therapy ◽  
Adrenergic Receptor ◽  
Dual Antiplatelet Therapy ◽  
Platelet Reactivity ◽  
Individual Variability ◽  
Platelet Response ◽  
Coronary Syndrome ◽  
Β2 Adrenergic Receptor

SummaryPlatelet response to clopidogrel shows inter-individual variability that is partially explained by genetic polymorphisms. This variability affects clinical outcome when clopidogrel is administered in patients with acute coronary syndrome (ACS). Catecholamines, released during ACS, contribute to platelet aggregation through platelet α2A- (α2A-AR) and β2-adrenergic receptor (β2-AR) stimulation. It was the objective of this study to assess the potential influence of α2A-AR and β2-AR gene polymorphisms on platelet reactivity after dual antiplatelet therapy with aspirin and clopidogrel in ACS. We screened 641 ACS patients for 6.3/6.7 kb α2A-AR polymorphism, and for Arg16Gly and Gln27Glu β2-AR polymorphism. After 600 mg clopidogrel, we assessed ADP 10 μmol-induced platelet aggregation (ADP-Ag) and vasoactive stimulated phosphoprotein (VASP). All single nucleotide polymorphisms were in Hardy-Weinberg equilibrium. A slight though negligible association was found between 6.3 kb allele of α2A-AR with platelet reactivity ADPAg induced (beta: –2.91 [-5.68;-0.14], p=0.04). A borderline not significant reduction in PRI VASP was observed in 6.3 kb α2A-AR carriers (beta: –3.81 [-0.09;7.72], p=0.06). No significant effect on platelet parameters was observed for the other tested polymorphisms. Common α2A- and β2-adrenergic receptor polymorphisms do not show any major impact on residual platelet reactivity in non-ST-elevation ACS when a dual antiplatelet therapy with 250 mg aspirin and 600 mg clopidogrel is administered.

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