Platelet Deposition Induced by Severely Damaged Vessel Wall Is Inhibited by a Boroarginine Synthetic Peptide with Antithrombin Activity

1994 ◽  
Vol 71 (04) ◽  
pp. 511-516 ◽  
Author(s):  
J J Badimon ◽  
D Weng ◽  
J H Chesebro ◽  
V Fuster ◽  
L Badimon
Keyword(s):  
Platelet Aggregation ◽  
Whole Blood ◽  
Synthetic Peptide ◽  
Ex Vivo ◽  
Thrombus Formation ◽  
Blood Platelet ◽  
Flow Conditions ◽  
Local Flow ◽  
Platelet Deposition ◽  
Damaged Vessel

SummaryThrombin plays a key role in platelet activation and thrombosis. Specific inhibition of thrombin appears to be one of the best approaches to prevent thrombus formation. We have studied the effects of a synthetic a-aminoboronic acid derivative - [Ac, (D) Phe-Pro-Boro-Arg-Hydrocloric acid] - on platelet deposition on severely damaged arterial wall. Platelet deposition was evaluated under well characterized rheological conditions in an original perfusion chamber and detected by autologous mIn-labeled platelets. The study was performed “in vivo” in a porcine model of arterial thrombosis triggered by severely damaged vessel wall at blood flow conditions mimicking mild stenosis (1690 s−1) and patent (212 s−1) vessels. In addition, ex-vivo platelet aggregation activity was evaluated by whole blood impedance aggregometry using collagen, ADP and thrombin as agonists. The synthetic a-aminoboronic peptide was intravenously administered as a bolus followed by continuous infusion. Ex vivo thrombin-induced whole blood platelet aggregation was totally abolished, while ADP- and Collagen-induced whole blood platelet aggregation was not modified. The effects of the synthetic antithrombin on platelet deposition were evaluated in native blood (non-anticoagulated) conditions and in combination with heparin. Under both experimental conditions, the synthetic peptide significantly inhibited platelet deposition at local flow conditions of both high (1690 s−1) and low (212s−1) shear rates. Our results suggest that specific inhibition of locally generated thrombin might be a good strategy to prevent platelet dependent arterial thrombus formation independently of the local flow shear rate of the area at risk.

Blockade of adenosine diphosphate receptors P2Y12 and P2Y1 is required to inhibit platelet aggregation in whole blood under flow

Blood ◽  
2001 ◽  
Vol 98 (12) ◽  
pp. 3340-3345 ◽  
Author(s):  
Nancy A. Turner ◽  
Joel L. Moake ◽  
Larry V. McIntire
Keyword(s):  
Platelet Aggregation ◽  
Whole Blood ◽  
Thrombus Formation ◽  
Direct Shear ◽  
Flow Conditions ◽  
Initial Adhesion ◽  
Platelet Deposition ◽  
Adp Receptors ◽  
Induced Aggregation ◽  
Control Samples

Abstract Using heparinized whole blood and flow conditions, it was shown that adenosine 5′-diphosphate (ADP) receptors P2Y12 and P2Y1 are both important in direct shear-induced platelet aggregation and platelet aggregation subsequent to initial adhesion onto von Willebrand factor (vWf)–collagen. In the viscometer, whole blood was subjected to shear rates of 750, 1500, and 3000 s−1 for 30 seconds at room temperature. The extent of aggregation was determined by flow cytometry. The P2Y12antagonist AR-C69 931MX (ARMX) reduced shear-induced aggregation at these rates by 56%, 54%, and 16%, respectively, compared to control samples. Adenosine 3′,5′-diphosphate (A3P5P; P2Y1antagonist) inhibited shear-induced aggregation by 40%, 30% and 29%, respectively, compared to control samples. Blockade of both ADP receptors at 3000 s−1 with ARMX plus A3P5P further reduced the platelet aggregation by 41% compared to the addition of ARMX alone (57% compared to control samples). Using a parallel-plate flow chamber, whole blood was perfused over bovine collagen type 1 at a wall shear rate of 3000 s−1 for 60 seconds. Platelet deposition was quantified with epifluorescence video microscopy and digital image processing. Blockade of P2Y12 alone or blockade of P2Y1 alone did not reduce thrombus formation on vWf–collagen. In contrast, blockade of both P2Y12 and P2Y1 reduced platelet deposition by 72%. These results indicate that combinations of antagonists of the ADP receptors P2Y12 and P2Y1 are effective inhibitors of direct shear-induced platelet aggregation and of platelet aggregation subsequent to initial adhesion under flow conditions. Inhibitors of these pathways are potentially useful as antiarterial thrombotic agents.

COMPARISON OF THE EFFECT OF ASPIRIN (ASA) AND CHOLINE MAGNESIUM TRISALICYLATE (CMT) ON PLATELET AGGREGATION IN WHOLE BLOOD EX-VIVO

1987 ◽  
Author(s):  
B J Z Danesh ◽  
A R Saniabadi ◽  
R I Russell ◽  
G D O Lowe ◽  
C D Forbes
Keyword(s):  
Platelet Aggregation ◽  
Whole Blood ◽  
Therapeutic Potential ◽  
Ex Vivo ◽  
Random Order ◽  
Blood Platelet ◽  
Bleeding Complications ◽  
Double Blind ◽  
Inhibition Of Platelet Aggregation ◽  
Spontaneous Aggregation

Suppression of platelet aggregation by ASA limits the therapeutic use of this drug as an analgesic in patients with bleeding tendencies. CMT is a non-acetylated salicylate derivative with analgesic and anti-inflammatory effect similar to that of ASA. We compared platelet aggregation in human whole blood ex-vivo, three hours after ingestion of ASA and. CMT. Using a whole blood platelet counter, platelet aggregation was quantified by measuring the fall in the number of single platelets at peak aggregation in response to collagen (lμg/ml) arachidonic acid (AA, 0.5 mM) as well as spontaneous aggregation. In double blind and random order, 12 healthy volunteers received a single oral dose of ASA and CMT containing 500 mg equivalent salicylate, on two separate occasions, 10 days apart. Despite a comparable absorption of salicylic acid from the two drugs, ingestion of ASA resulted in a marked inhibition of platelet aggregation induced by collagen, AA and spontaneous aggregation, whereas such effects were not observed after CMT ingestion.We suggest that CMT may have therapeutic potential as an alternative to aspirin when inhibition of platelet aggregation can induce bleeding complications.

Whole blood platelet deposition on extracellular matrix under flow conditions in preterm neonatal sepsis

2002 ◽  
Vol 161 (5) ◽  
pp. 270-274 ◽  
Author(s):  
Yaron Finkelstein ◽  
Boris Shenkman ◽  
Lea Sirota ◽  
Tali H. Vishne ◽  
Rima Dardik ◽  
...  
Keyword(s):  
Extracellular Matrix ◽  
Whole Blood ◽  
Neonatal Sepsis ◽  
Blood Platelet ◽  
Flow Conditions ◽  
Platelet Deposition

A Prostacyclin-sparing Effect of Indobufen vs. Aspirin

1996 ◽  
Vol 75 (03) ◽  
pp. 510-514 ◽  
Author(s):  
R De Caterina ◽  
D Giannessi ◽  
W Bernini ◽  
G Lazzerini ◽  
M Lavezzari ◽  
...  
Keyword(s):  
Arachidonic Acid ◽  
Platelet Aggregation ◽  
Whole Blood ◽  
Ex Vivo ◽  
Blood Platelet ◽  
Tolerability Profile ◽  
Double Blind ◽  
Baseline Serum ◽  
Cyclooxygenase Inhibition ◽  
Blood Platelet Aggregation

SummaryIndobufen ((±)-2-[p-(l-oxo-2-insoindolinyl)-phenyI]-butyric acid, indo) is a drug inhibiting platelet function by a reversible block of the arachidonic acid metabolism at the level of cyclooxygenase. Since tolerability profile of such drugs is mostly linked to extra-platelet cyclooxygenase inhibition, we prospectively evaluated the extent of platelet and extra-platelet cyclooxygenase inhibition by in vivo administration of indo in comparison with ASA. We assessed the effects of the two drugs on the ex vivo generation of TXB2 and 6-keto-PGFlΑ in whole blood, as indices of the production of TXA2 and PGI2 (prostacyclin), respectively, either after spontaneous clotting at 37° C for 1 h (Study 1) or after the addition of 2 Μg/ml collagen (Study 2). Generation of 6-keto-PGFlΑ in whole blood is a mixed index of platelet and extra-platelet cyclooxygenase activity, deriving from both platelet and white blood cell arachidonic acid metabolization. Fifteen patients with ischemic heart disease and baseline serum TXB2 levels > 300 ng/ml were allocated to receiving one single administration of either indobufen 200 mg (n = 6) or aspirin 500 mg (n = 9). Whole blood prostanoid generation was assessed at 0,1,2,4,6, 8,12 and 24 h after drug administration (Study 1). Ten healthy male volunteers were allocated to a double-blind, randomized crossover comparison of indo 200 mg b.i.d. vs. ASA 300 mg/d for 7 days (Study 2). Prostanoid generation and whole blood platelet aggregation were performed before and at the end of each study period (Day 0 and Day 7). At each time-point after single dose administration (Study 1), indobufen caused less % inhibition of whole blood 6-keto-PGFlΑ than of TXB2. At 2 h, TXB2 was reduced to a similar extent after ASA (98 ± 4%) and indo (97 ± 6%) (p = N.S.), while inhibition of 6-keto-PGFla was clearly different (> 98% after ASA, 81 ± 2.5% after indo, p < 0.01). After one week of ASA or indo (Study 2) the maximum extent of whole blood platelet aggregation was similarly inhibited (from 17.2 ± 1.4 ohms to 3.6 ± 1.3 ohms with ASA; from 18.3 ± 1.0 ohms to 1.6 ± 0.7 ohms with indo (p ASA vs. indo = N. S.). Despite equal inhibition of whole blood TX production after collagen (from 49.0 ± 4.3 ng/ml to 1.1 ± 0.6 ng/ml with ASA, from 49.8 ± 1.3 ng/ml to 1.4 ± 0.6 ng/ml with indo), again, however, 6-keto-PGFlΑ production was less affected by indo than by ASA (from 409 ± 30 pg/ml to 37 ± 13 pg/ml with ASA, inhibition = 91%; from 396 ± 35 to 318 ± 40 with indo, inhibition = 20%). These differential effects of indo and ASA might lead to a better platelet selectivity, tolerability and benefit/risk profile of indo vs. ASA, which are worthy of further assessment.

Matrix metalloproteinase-2 enhances platelet deposition on collagen under flow conditions

2016 ◽  
Vol 115 (02) ◽  
pp. 333-343 ◽  
Author(s):  
Stefania Momi ◽  
Philip G. de Groot ◽  
Monica Battiston ◽  
Luigi de Marco ◽  
Emanuela Falcinelli ◽  
...  
Keyword(s):  
Matrix Metalloproteinase ◽  
Platelet Activation ◽  
Whole Blood ◽  
Thrombus Formation ◽  
Vascular Wall ◽  
Matrix Metalloproteinase 2 ◽  
High Shear ◽  
Flow Conditions ◽  
Filtration System ◽  
Platelet Deposition

SummaryPlatelets contain and release matrix metalloproteinase-2 (MMP-2) that in turn potentiates platelet aggregation. Platelet deposition on a damaged vascular wall is the first, crucial, step leading to thrombosis. Little is known about the effects of MMP-2 on platelet activation and adhesion under flow conditions. We studied the effect of MMP-2 on shear-dependent platelet activation using the O’Brien filtration system, and on platelet deposition using a parallel-plate perfusion chamber. Preincubation of human whole blood with active MMP-2 (50 ng/ml, i. e. 0.78 nM) shortened filter closure time (from 51.8 ± 3.6 sec to 40 ± 2.7 sec, p< 0.05) and increased retained platelets (from 72.3 ± 2.3 % to 81.1 ± 1.8 %, p< 0.05) in the O’Brien system, an effect prevented by a specific MMP-2 inhibitor. High shear stress induced the release of MMP-2 from platelets, while TIMP-2 levels were not significantly reduced, therefore, the MMP-2/TIMP-2 ratio increased significantly showing enhanced MMP-2 activity. Preincubation of whole blood with active MMP-2 (0.5 to 50 ng/ml, i.e 0.0078 to 0.78 nM) increased dose-dependently human platelet deposition on collagen under high shear-rate flow conditions (3000 sec-1) (maximum +47.0 ± 11.9 %, p< 0.05, with 50 ng/ml), while pre-incubation with a MMP-2 inhibitor reduced platelet deposition. In real-time microscopy studies, increased deposition of platelets on collagen induced by MMP-2 started 85 sec from the beginning of perfusion, and was abolished by a GPIIb/IIIa antagonist, while MMP-2 had no effect on platelet deposition on fibrinogen or VWF. Confocal microscopy showed that MMP-2 enhances thrombus volume (+20.0 ± 3.0 % vs control) rather than adhesion. In conclusion, we show that MMP-2 potentiates shear-induced platelet activation by enhancing thrombus formation.Supplementary Material to this article is available online at www.thrombosis-online.com.

The effect of ex vivo anticoagulants on whole blood platelet aggregation

Platelets ◽  
2009 ◽  
Vol 20 (1) ◽  
pp. 7-11 ◽  
Author(s):  
Madeleine L. Kalb ◽  
Lukasz Potura ◽  
Gisela Scharbert ◽  
Sibylle A. Kozek-Langenecker
Keyword(s):  
Platelet Aggregation ◽  
Whole Blood ◽  
Ex Vivo ◽  
Blood Platelet ◽  
Blood Platelet Aggregation

General Medicine: Effects of Aspirin on Platelet Aggregation in Smokers and Nonsmokers

1997 ◽  
Vol 31 (3) ◽  
pp. 290-293 ◽  
Author(s):  
Clarence Chant ◽  
Susan C Fagan ◽  
Sheena K Aurora ◽  
Barry E Gidal ◽  
Rajiv Joseph
Keyword(s):  
Platelet Aggregation ◽  
Healthy Volunteers ◽  
Whole Blood ◽  
Ex Vivo ◽  
Smoking Status ◽  
Outcome Measurement ◽  
Tertiary Care ◽  
Atp Release ◽  
General Medicine ◽  
Blood Platelet

Objective To assess the relative antiaggregatory ability of aspirin on platelets of smoking and nonsmoking healthy volunteers. Design Prospective, randomized, crossover study. Setting Tertiary-care teaching institution. Subjects Eighteen healthy smoking and nonsmoking male volunteers. Interventions Each subject received aspirin 325 mg or ticlopidine 250 mg bid as an active control for 7 days in a crossover manner separated by a 1-month washout period. Whole blood platelet aggregation was measured on four occasions, twice at baseline and once after each drug treatment. Outcome Measurement Whole blood ex vivo platelet aggregation in terms of impedance (Ω) and adenosine triphosphate (ATP) release (nmol), as assessed using Lumi-aggregometry. Results Aspirin was associated with significantly less ATP release in both smokers (p = 0.01) and nonsmokers (p = 0.003). No significant differences in platelet aggregation were found between smokers and nonsmokers at baseline or with any treatment phases. Sixty-seven percent and 17% of volunteers receiving ticlopidine and aspirin, respectively, reported adverse effects. Conclusions Twice-daily administration of aspirin for 7 days to healthy volunteers was well tolerated and also reduced platelet aggregation significantly regardless of smoking status.

Effects of Acetylsalicylic Acid on Inhibition of Ex Vivo Platelet Aggregation and Secretion by SKF 107260, a Novel GPIIb/IIIa Receptor Antagonist

1994 ◽  
Vol 72 (04) ◽  
pp. 622-626 ◽  
Author(s):  
Martin I Freed ◽  
Steven Boike ◽  
Nevine Zariffa ◽  
Diane K Jorkasky
Keyword(s):  
Platelet Aggregation ◽  
Acetylsalicylic Acid ◽  
Whole Blood ◽  
Ex Vivo ◽  
Atp Release ◽  
Blood Platelet ◽  
Inhibition Of Platelet Aggregation ◽  
Dependent Inhibition ◽  
Platelet Secretion

SummarySKF 107260 is a potent pentapeptide antagonist of the platelet membrane glycoprotein receptor GP IIb/IIIa. The in vitro platelet inhibitory effects of SKF 107260, acetylsalicylic acid (ASA), and their combination, on collagen-induced platelet aggregation and secretion (ATP release) were assessed in human whole blood. Additionally, the con-centration-response relationships for these inhibitors were compared for males and females in order to explore gender differences in platelet responsiveness. SKF 107260 caused a concentration-dependent inhibition of platelet aggregation which was significant at concentrations ≥30 nM. ASA also caused a concentration-dependent inhibition of platelet aggregation which was significant at concentrations ≥ 1 mg/dl. The addition of ASA 1 mg/dl to increasing concentrations of SKF 107260 resulted in a more pronounced inhibition of platelet aggregation than when either agent was used alone. These data suggest a pharmacologic interaction, especially at SKF 107260 concentrations ≤30 nM. Since ATP release was significantly inhibited at concentrations ≥ 1 nM, platelet secretion appears to be more sensitive than aggregation to inhibition by SKF 107260. These data suggest that platelet secretion in response to collagen is dependent on the aggregation response mediated by GP IIb/IIIa. In conclusion, SKF 107260 is a potent inhibitor of both whole blood platelet aggregation and secretion and these anti-aggregatory effects may be augmented by concomitant ASA administration.

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