Antithrombotic Effects and Bleeding Time Prolongation with Synthetic Platelet GPIIb/llla Inhibitors in Animal Models of Platelet-Mediated Thrombosis

1994 ◽  
Vol 71 (01) ◽  
pp. 095-102 ◽  
Author(s):  
Désiré Collen ◽  
Hua Rong Lu ◽  
Jean-Marie Stassen ◽  
Ingrid Vreys ◽  
Tsunehiro Yasuda ◽  
...  
Keyword(s):  
Platelet Aggregation ◽  
Bleeding Time ◽  
Bolus Injection ◽  
Cell Injury ◽  
Ex Vivo ◽  
Thrombus Formation ◽  
Femoral Vein ◽  
Thrombotic Occlusion ◽  
Antithrombotic Effects

SummaryCyclic Arg-Gly-Asp (RGD) containing synthetic peptides such as L-cysteine, N-(mercaptoacetyl)-D-tyrosyl-L-arginylglycyl-L-a-aspartyl-cyclic (1→5)-sulfide, 5-oxide (G4120) and acetyl-L-cysteinyl-L-asparaginyl-L-prolyl-L-arginyl-glycyl-L-α-aspartyl-[0-methyltyrosyl]-L-arginyl-L-cysteinamide, cyclic 1→9-sulfide (TP9201) bind with high affinity to the platelet GPIIb/IIIa receptor.The relationship between antithrombotic effect, ex vivo platelet aggregation and bleeding time prolongation with both agents was studied in hamsters with a standardized femoral vein endothelial cell injury predisposing to platelet-rich mural thrombosis, and in dogs with a carotid arterial eversion graft inserted in the femoral artery. Intravenous administration of G4120 in hamsters inhibited in vivo thrombus formation with a 50% inhibitory bolus dose (ID50) of approximately 20 μg/kg, ex vivo ADP-induccd platelet aggregation with ID50 of 10 μg/kg, and bolus injection of 1 mg/kg prolonged the bleeding time from 38 ± 9 to 1,100 ± 330 s. Administration of TP9201 in hamsters inhibited in vivo thrombus formation with ID50 of 30 μg/kg, ex vivo platelet aggregation with an ID50 of 50 μg/kg and bolus injection of 1 mg/kg did not prolong the template bleeding time. In the dog eversion graft model, infusion of 100 μg/kg of G4120 over 60 min did not fully inhibit platelet-mediated thrombotic occlusion but was associated with inhibition of ADP-induccd ex vivo platelet aggregation and with prolongation of the template bleeding time from 1.3 ± 0.4 to 12 ± 2 min. Infusion of 300 μg/kg of TP9201 over 60 min completely prevented thrombotic occlusion, inhibited ex vivo platelet aggregation, but was not associated with prolongation of the template bleeding time.TP9201, unlike G4120, inhibits in vivo platelet-mediated thrombus formation without associated prolongation of the template bleeding time.

Antithrombotic Effect of a Recombinant von Willebrand Factor, VCL, on Nitrogen Laser-Induced Thrombus Formation in Guinea Pig Mesenteric Arteries

1995 ◽  
Vol 73 (02) ◽  
pp. 318-323 ◽  
Author(s):  
K Azzam ◽  
L I Garfinkel ◽  
C Bal dit Sollier ◽  
M Cisse Thiam ◽  
L Drouet
Keyword(s):  
Platelet Aggregation ◽  
Bleeding Time ◽  
Ex Vivo ◽  
Thrombus Formation ◽  
Mesenteric Arteries ◽  
Antithrombotic Effects ◽  
Von Willebrand ◽  
Willebrand Factor

SummaryTo assess the antithrombotic effectiveness of blocking the platelet glycoprotein (GP) Ib/IX receptor for von Willebrand factor (vWF), the antiaggregating and antithrombotic effects were studied in guinea pigs using a recombinant fragment of vWF, Leu 504-Lys 728 with a single intrachain disulfide bond linking residues Cys 509-Cys 695. The inhibitory effect of this peptide, named VCL, was tested in vitro on ristocetin- and botrocetin-induced platelet aggregation and compared to the ADP-induced platelet aggregation. In vivo, the antithrombotic effect of VCL was tested in a model of laser-injured mesentery small arteries and correlated to the ex vivo ristocetin-induced platelet aggregation. In this model of laser-induced thrombus formation, five mesenteric arteries were studied in each animal, and the number of recurrent thrombi during 15 min, the time to visualization and time to formation of first thrombus were recorded.In vitro, VCL totally abolished ristocetin- and botrocetin-induced platelet aggregation, but had no effect on ADP-induced platelet aggregation. Ex vivo, VCL (0.5 to 2 mg/kg) administered as a bolus i. v. injection inhibits ristocetin-induced platelet aggregation with a duration of action exceeding 1 h. The maximum inhibition was observed 5 min after injection of VCL and was dose related. The same doses of VCL had no significant effect on platelet count and bleeding time. In vivo, VCL (0.5 to 2 mg/kg) had no effect on the appearance of the thrombi formed but produced dose-dependent inhibition of the mean number of recurrent thrombi (the maximal effect was obtained at 5 min following i. v. injection of the highest dose: 0.8 ± 0.2 thrombi versus 4 ± 0.4 thrombi in controls). The three doses of VCL increased the time in which the first thrombus in a concentration-dependent manner was formed. However, the time to visualize the first thrombus was only prolonged in the higher dose-treated group.These in-vivo studies confirm that VCL induces immediate, potent, and transient antithrombotic effects. Most importantly, this inhibition was achieved without inducing thrombocytopenia nor prolongation of the bleeding time.

Antiplatelet and Antithrombotic Effects of YM337, the Fab Fragment of a Humanized Anti-GPIIb/IIIa Monoclonal Antibody in Monkeys

1996 ◽  
Vol 75 (04) ◽  
pp. 679-684 ◽  
Author(s):  
Seiji Kaku ◽  
Tomihisa Kawasaki ◽  
Nami Hisamichi ◽  
Yumiko Sakai ◽  
Yuta Taniuchi ◽  
...  
Keyword(s):  
Monoclonal Antibody ◽  
Arachidonic Acid ◽  
Platelet Aggregation ◽  
Bleeding Time ◽  
Bolus Injection ◽  
Ex Vivo ◽  
Thrombus Formation ◽  
Fab Fragment ◽  
Inhibition Of Platelet Aggregation ◽  
Antithrombotic Effects

SummaryThe antiplatelet and antithrombotic effects of the Fab fragment of the humanized antiplatelet glycoprotein (GP) IIb/IIIa monoclonal antibody C4G1 (YM337) were investigated in monkeys. First, the relationship between the inhibition of platelet aggregation and the prolongation of bleeding time was studied in rhesus monkeys. YM337 dose-dependently inhibited ex vivo platelet aggregation, with complete inhibition at doses higher than 0.25 mg/kg intravenous injection or 1.5 μg/kg/min infusion. At 0.25 mg/kg bolus injection followed by 1.5 μg/kg/min infusion, YM337 immediately and continuously inhibited platelet aggregation during the 6-h infusion period with platelet aggregation rapidly returning to over 50% of baseline within 1 h after the cessation of infusion. Template-bleeding time was significantly prolonged during the period of complete inhibition of platelet aggregation.Second, the antithrombotic effects of YM337 were investigated in a photochemically-induced thrombosis model in squirrel monkeys. YM337 at a dose of 1 mg/kg intravenous injection followed by 6 μg/kg/min infusion for 60 min prevented occlusive thrombus formation in all 4 monkeys. In contrast, time to occlusive thrombus formation did not change on intravenous bolus injection of aspirin 17 mg/kg (11.3 ± 5.2 min) or sodium ozagrel (9.4 ± 3.0 min) compared with saline (13.3 ± 4.0 min). YM337 but not aspirin or sodium ozagrel significantly inhibited ex vivo ADP-induced platelet aggregation, while all drugs completely inhibited arachidonic acid-induced platelet aggregation. However, while aspirin and sodium ozagrel inhibited the thromboxane B2 generation accompanying arachidonic acid-induced platelet aggregation, YM337 had no effect on this variable. Platelet counts and bleeding time showed no significant change in any group in this squirrel monkey model.These results indicate that YM337, with a short half-life, may be a useful therapeutic agent in patients with thrombotic disorders.

scholarly journals Calin from Hirudo medicinalis, an inhibitor of platelet adhesion to collagen, prevents platelet-rich thrombosis in hamsters

Blood ◽  
1995 ◽  
Vol 85 (3) ◽  
pp. 712-719 ◽  
Author(s):  
H Deckmyn ◽  
JM Stassen ◽  
I Vreys ◽  
E Van Houtte ◽  
RT Sawyer ◽  
...  
Keyword(s):  
Platelet Adhesion ◽  
Bleeding Time ◽  
Ex Vivo ◽  
Thrombus Formation ◽  
Femoral Vein ◽  
Video Recording ◽  
Hirudo Medicinalis ◽  
Thrombosis Model

Interaction between exposed collagen and platelets and/or von Willebrand factor is believed to be one of the initiating events for thrombus formation at sites of damaged endothelium. Interference with this mechanism may provide an anti-thrombotic potential. Calin, a product from the saliva of the leech Hirudo medicinalis, was tested in vitro and for its in vivo activity in a thrombosis model in hamsters. Calin specifically and dose dependently (IC50:6.5 to 13 micrograms/mL) inhibited human platelet aggregation induced by collagen. In addition, specific platelet adhesion onto microtiter wells coated with collagen and detected with a monoclonal antiglycoprotein IIb/IIIa antibody- conjugated with horseradish peroxidase, could be completely prevented with Calin (IC50:22 micrograms/mL). A dose-response curve was constructed in groups of six hamsters in whom a standardized trauma was induced on the femoral vein. Thrombus formation was followed continuously using video recording and processing of the image obtained upon transillumination of the vessel. Intravenous Calin dose- dependently inhibited platelet-rich thrombus formation in this model with an ED50 of 0.07 mg/kg and complete inhibition with 0.2 mg/kg. No effects were seen on coagulation tests or bleeding times, whereas ex vivo aggregation induced by collagen was inhibited dose dependently. Local application of leech saliva, Calin, hirudin, or the combination of the latter two into the bleeding time wound of hamsters resulted in a mild prolongation of the bleeding time (twofold to threefold). A similar experiment in baboons did not cause any prolongation of the bleeding time. This is in sharp contrast with the long-lasting bleeding after a leech bite itself in both species. Calin from the leech Hirudo medicinalis is able, by binding to collagen, to effectively interfere with platelet-collagen interaction, which results in an antithrombotic effect observed in a platelet-rich thrombosis model in hamsters.

Prevention of Canine Coronary Artery Thrombosis with Echistatin, a Potent Inhibitor of Platelet Aggregation from the Venom of the Viper, Echis carmatus

1990 ◽  
Vol 64 (04) ◽  
pp. 576-581 ◽  
Author(s):  
Ronald J Shebuski ◽  
Denise R Ramjit ◽  
Gary R Sitko ◽  
Patricia K Lumma ◽  
Victor M Garsky
Keyword(s):  
Coronary Artery ◽  
Platelet Aggregation ◽  
Bleeding Time ◽  
Ex Vivo ◽  
Platelet Rich Plasma ◽  
Thrombus Formation ◽  
Artery Thrombosis ◽  
Coronary Artery Thrombosis ◽  
Canine Coronary Artery

SummaryA model of acute, platelet-dependent canine coronary artery thrombosis was utilized to assess the antithrombotic effect of a synthetic, RGD-containing 49-residue protein termed echistatin. This protein is derived from the venom of the viper, Echis carinatus. In vitro, echistatin inhibited ADP (10 ΜM)-induced platelet aggregation with IC50 values in human and canine platelet-rich plasma of 101 ± 4 and 127 ± 32 nM, respectively. In vivo, in the dog, infusion of echistatin for 30 min at 20 pg kg−1 min−1 or 2.6 nM kg−1 min−1 resulted in total abolition of acute platelet-dependent coronary thrombus formation in all dogs tested (n = 5). Infusion of a lower dose (10 pg kg−1 min−1) was not effective in prevention of thrombus formation. Blood samples were taken before and after infusion of echistatin in order to determine ex vivo platelet aggregatory responses. Echistatin (20 pg kg−1 min−1, i.v.) attenuated ex vivo platelet aggregation elicited by ADP, U-46619 and collagen and increased bleeding time by 2.9 ± 0.5-fold over control. Thus, in the dog, echistatin is an effective antithrombotic agent inhibiting both platelet aggregation in vivo in the coronary artery as well as ex vivo with a concomitant increase in bleeding time. Furthermore, the effects of echistatin on platelet aggregation and bleeding time are reversible with restoration to control levels occurring 30-60 min after termination of the infusion.

The Effect of Prostacyclin (PGI2) on Platelet Behaviour. Thrombus Formation in Vivo and Bleeding Time

1979 ◽  
Vol 41 (02) ◽  
pp. 425-435 ◽  
Author(s):  
Fernando B Ubatuba ◽  
Salvador Moncada ◽  
John R Vane
Keyword(s):  
Platelet Aggregation ◽  
Prostaglandin E1 ◽  
Bleeding Time ◽  
Potent Inhibitor ◽  
Ex Vivo ◽  
Thrombus Formation ◽  
Phosphodiesterase Inhibitor ◽  
Concomitant Administration ◽  
Prostaglandin D2

SummaryProstacyclin (PGI2) infused intravenously into anaesthetized rabbits inhibited electrically-induced thrombus formation in the carotid artery, increased bleeding time and inhibited ex vivo platelet aggregation induced by ADP or arachidonic acid. The increase in bleeding time and the inhibition of ex vivo platelet aggregation lasted for as long as the infusion of PGI2 was maintained but rapidly disappeared after infusion was stopped.Prostacyclin is a more potent inhibitor of platelet function, in vivo than prostaglandin E1 (PGE1) or prostaglandin D2 (PGD2).The effects of prostacyclin on all parameters studied except blood pressure were potentiated by the concomitant administration of theophylline, a phosphodiesterase inhibitor.

Anti-Human VWF Monoclonal Antibody SZ-123 Prevents Arterial Thrombus Formation by Inhibiting VWF–collagen and VWF-Platelet Interactions in Rhesus Monkeys

Blood ◽  
2012 ◽  
Vol 120 (21) ◽  
pp. 5194-5194
Author(s):  
Yiming Zhao ◽  
Changgeng Ruan
Keyword(s):  
Monoclonal Antibody ◽  
Platelet Aggregation ◽  
Bleeding Time ◽  
Conflicts Of Interest ◽  
Ex Vivo ◽  
Thrombus Formation ◽  
Significant Prolongation ◽  
Arterial Thrombus

Abstract Abstract 5194 Objective: To investigate the in vivo antithrombotic efficacy of an anti-VWF monoclonal antibody SZ-123, and its potential underlying mechanism. Methods and Results: Cyclic flow reductions (CFRs) were measured in the femoral artery of monkeys before and after intravenous administration of SZ-123. Ex vivo VWF binding to collagen, platelet aggregation, platelet count and template bleeding time were performed as measurements of antithrombotic activity. In addition, plasma VWF, SZ-123 levels, and VWF occupancy were measured by ELISA. Administration of 0. 1, 0. 3, and 0. 6 mg/kg SZ-123 resulted in 45. 3%, 78. 2%, and 100% reduction in CFRs, respectively. When 0. 3 and 0. 6 mg/kg SZ-123 were administrated, 100% of VWF was occupied by the antibody. Moreover, 100% ex vivo inhibition of VWF-collagen binding and 60–95% inhibition of platelet aggregation were observed from 15 min to 1h. None of the doses resulted in significant prolongation of bleeding time. In vitro experiment also revealed that SZ-123 not only blocks collagen-VWF A3 interaction but also inhibits indirectly VWF A1 binding to GPIba induced by ristocetin. Conclusions: SZ-123 prevents in vivo arterial thrombus formation under high shear conditions by inhibiting VWF A3–collagen and VWF A1-platelet interactions and does not prolong bleeding time. Disclosures: No relevant conflicts of interest to declare.

The Antiaggregating and Antithrombotic Activity of Clopidogrel Is Potentiated by Aspirin in Several Experimental Models in the Rabbit

1998 ◽  
Vol 80 (09) ◽  
pp. 512-518 ◽  
Author(s):  
Frédérique Dol ◽  
André Bernat ◽  
Robert Falotico ◽  
Alain Lalé ◽  
Pierre Savi ◽  
...  
Keyword(s):  
Platelet Aggregation ◽  
Carotid Artery ◽  
Ex Vivo ◽  
Thrombus Formation ◽  
Experimental Models ◽  
Arteriovenous Shunt ◽  
Thrombotic Occlusion ◽  
Antithrombotic Activity ◽  
Rabbit Carotid Artery ◽  
Antithrombotic Efficacy

SummaryIt is unknown whether the addition of aspirin might increase both the efficacy and the potency of clopidogrel, a potent and selective ADP blocker. For that purpose, the efficacy of clopidogrel (1–20 mg/kg, p.o.) administered orally to rabbits alone or in combination with aspirin (0.1–10 mg/kg, p.o.) was determined in several experimental models. A potent synergistic effect of the clopidogrel/aspirin association was demonstrated with regard to collagen-induced platelet aggregation measured ex vivo. Similarly, aspirin potentiated the antithrombotic activity of clopidogrel measured with regard to experimental thrombosis induced by a silk thread or on stents placed in an arteriovenous shunt, thrombus formation following electrical stimulation of the rabbit carotid artery and with regard to 111In-labeled platelet deposition on a stent implanted in an arteriovenous shunt or on the subendothelium following air drying injury of the rabbit carotid artery. A similar potentiating effect of aspirin was obtained with regard to myointimal proliferation (restenosis) in the femoral arteries of atherosclerotic rabbits which occurred as a consequence of stent placement. The clopidogrel/aspirin combination showed only additive-type effects on bleeding time prolongation induced by ear transection in the rabbit, therefore showing that combined inhibition of cyclooxygenase and ADP‘s effects provide a marked enhanced antithrombotic efficacy. Such a combination may provide substantial protection against platelet aggregation leading to thrombotic occlusion at sites of endothelial injuries and coronary artery stenosis in humans.

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.

scholarly journals Antithrombotic Effect of Crotalin, a Platelet Membrane Glycoprotein Ib Antagonist From Venom of Crotalus atrox

Blood ◽  
1998 ◽  
Vol 91 (5) ◽  
pp. 1582-1589
Author(s):  
Mei-Chi Chang ◽  
Hui-Kuan Lin ◽  
Hui-Chin Peng ◽  
Tur-Fu Huang
Keyword(s):  
Platelet Aggregation ◽  
Latent Period ◽  
Bleeding Time ◽  
Thrombus Formation ◽  
Platelet Membrane ◽  
Dependent Manner ◽  
Glycoprotein Ib ◽  
Platelet Surface ◽  
Dose Dependent

A potent platelet glycoprotein Ib (GPIb) antagonist, crotalin, with a molecular weight of 30 kD was purified from the snake venom ofCrotalus atrox. Crotalin specifically and dose dependently inhibited aggregation of human washed platelets induced by ristocetin with IC50 of 2.4 μg/mL (83 nmol/L). It was also active in inhibiting ristocetin-induced platelet aggregation of platelet-rich plasma (IC50, 6.3 μg/mL). 125I-crotalin bound to human platelets in a saturable and dose-dependent manner with a kd value of 3.2 ± 0.1 × 10−7 mol/L, and its binding site was estimated to be 58,632 ± 3,152 per platelet. Its binding was specifically inhibited by a monoclonal antibody, AP1 raised against platelet GPIb. Crotalin significantly prolonged the latent period in triggering platelet aggregation caused by low concentration of thrombin (0.03 U/mL), and inhibited thromboxane B2formation of platelets stimulated either by ristocetin plus von Willebrand factor (vWF), or by thrombin (0.03 U/mL). When crotalin was intravenously (IV) administered to mice at 100 to 300 μg/kg, a dose-dependent prolongation on tail bleeding time was observed. The duration of crotalin in prolonging tail bleeding time lasted for 4 hours as crotalin was given at 300 μg/kg. In addition, its in vivo antithrombotic activity was evidenced by prolonging the latent period in inducing platelet-rich thrombus formation by irradiating the mesenteric venules of the fluorescein sodium-treated mice. When administered IV at 100 to 300 μg/kg, crotalin dose dependently prolonged the time lapse in inducing platelet-rich thrombus formation. In conclusion, crotalin specifically inhibited vWF-induced platelet agglutination in the presence of ristocetin because crotalin selectively bound to platelet surface receptor-glycoprotein Ib, resulting in the blockade of the interaction of vWF with platelet membrane GPIb. In addition, crotalin is a potent antithrombotic agent because it pronouncedly blocked platelet plug formation in vivo.

scholarly journals Antithrombotic Effect of Crotalin, a Platelet Membrane Glycoprotein Ib Antagonist From Venom of Crotalus atrox

Blood ◽  
1998 ◽  
Vol 91 (5) ◽  
pp. 1582-1589 ◽  
Author(s):  
Mei-Chi Chang ◽  
Hui-Kuan Lin ◽  
Hui-Chin Peng ◽  
Tur-Fu Huang
Keyword(s):  
Platelet Aggregation ◽  
Latent Period ◽  
Bleeding Time ◽  
Thrombus Formation ◽  
Platelet Membrane ◽  
Dependent Manner ◽  
Glycoprotein Ib ◽  
Platelet Surface ◽  
Dose Dependent

AbstractA potent platelet glycoprotein Ib (GPIb) antagonist, crotalin, with a molecular weight of 30 kD was purified from the snake venom ofCrotalus atrox. Crotalin specifically and dose dependently inhibited aggregation of human washed platelets induced by ristocetin with IC50 of 2.4 μg/mL (83 nmol/L). It was also active in inhibiting ristocetin-induced platelet aggregation of platelet-rich plasma (IC50, 6.3 μg/mL). 125I-crotalin bound to human platelets in a saturable and dose-dependent manner with a kd value of 3.2 ± 0.1 × 10−7 mol/L, and its binding site was estimated to be 58,632 ± 3,152 per platelet. Its binding was specifically inhibited by a monoclonal antibody, AP1 raised against platelet GPIb. Crotalin significantly prolonged the latent period in triggering platelet aggregation caused by low concentration of thrombin (0.03 U/mL), and inhibited thromboxane B2formation of platelets stimulated either by ristocetin plus von Willebrand factor (vWF), or by thrombin (0.03 U/mL). When crotalin was intravenously (IV) administered to mice at 100 to 300 μg/kg, a dose-dependent prolongation on tail bleeding time was observed. The duration of crotalin in prolonging tail bleeding time lasted for 4 hours as crotalin was given at 300 μg/kg. In addition, its in vivo antithrombotic activity was evidenced by prolonging the latent period in inducing platelet-rich thrombus formation by irradiating the mesenteric venules of the fluorescein sodium-treated mice. When administered IV at 100 to 300 μg/kg, crotalin dose dependently prolonged the time lapse in inducing platelet-rich thrombus formation. In conclusion, crotalin specifically inhibited vWF-induced platelet agglutination in the presence of ristocetin because crotalin selectively bound to platelet surface receptor-glycoprotein Ib, resulting in the blockade of the interaction of vWF with platelet membrane GPIb. In addition, crotalin is a potent antithrombotic agent because it pronouncedly blocked platelet plug formation in vivo.

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