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Updated: Mar 14, 2026
Routine Screening Method for Microparticles in Platelet Transfusions
Published on: January 31, 2018
Antiplatelet Agents Inhibit the Generation of Platelet-Derived Microparticles
Abstract:
Platelet microparticles (PMPs) contribute to thrombogenesis but the effects of antiplatelet drugs on PMPs generation is undefined. The present study investigated the cellular events regulating PMPs shedding, testing in vitro platelet agonists and inhibitors. Platelet-rich plasma from healthy subjects was stimulated with arachidonic acid (AA), U46619, collagen type-I (10 and 1.5 μg/mL), epinephrine, ADP or TRAP-6 and pre-incubated with acetylsalicylic acid (ASA, 100 and 10 μmol/L), SQ-29,548, apyrase, PSB-0739, or eptifibatide. PMPs were detected by flow-cytometry using CD61 and annexin-V as fluorescent markers. Platelet agonists induced annexin V-positive PMPs shedding. The strongest response was to high concentration collagen. ADP-triggered PMPs shedding was dose-independent. ASA reduced PMPs induced by AA- (645, 347-2946 vs. 3061, 446-4901 PMPs/μL; median ad range, n = 9, P < 0.001), collagen 10 μg/mL (5317, 2027-15935 vs. 10252, 4187-46316 PMPs/μL; n = 13, P < 0.001), collagen 1.5 μg/mL (1078, 528-2820 vs. 1465, 582-5948 PMPs/μL; n = 21, P < 0.001) and TRAP-6 (2008, 1621-2495 vs. 2840, 2404-3031 PMPs/μL; n = 3, P < 0.01) but did not affect the response to epinephrine or ADP. The ADP scavenger apyrase reduced PMPs induced by U46619 (1256, 395-2908 vs. 3045, 1119-5494 PMPs/μL, n = 6, P < 0.05), collagen 1.5 μg/mL (1006, 780-1309 vs. 2422, 1839-3494 PMPs/μL, n = 3, P < 0.01) and TRAP-6 (904, 761-1224 vs. 2840, 2404-3031 PMPs/μL, n = 3, P < 0.01). The TP receptor antagonist SQ-29,548 and the P2Y12 receptor antagonist PSB-0739 markedly inhibited PMPs induced by low doses of collagen. Except for high-dose collagen, eptifibatide abolished agonist-induced PMPs release. Both TXA2 generation and ADP secretion are required as amplifiers of PMP shedding. The crucial role of the fibrinogen receptor and the collagen receptor in PMPs generation, independently of platelet aggregation, was identified.
Insights
Antiplatelet drugs like aspirin significantly reduce platelet microparticle (PMP) generation induced by various agonists. This study reveals that both thromboxane A2 generation and ADP secretion amplify PMP shedding, highlighting key receptors involved.
Area of Science:
- Hematology
- Pharmacology
- Cardiovascular Research
Background:
- Platelet microparticles (PMPs) are implicated in thrombogenesis.
- The impact of antiplatelet medications on PMP generation remains incompletely understood.
Purpose of the Study:
- To investigate the cellular mechanisms regulating PMP shedding.
- To evaluate the effects of various antiplatelet agents on PMP generation in vitro.
Main Methods:
- Platelet-rich plasma from healthy donors was stimulated with agonists (arachidonic acid, U46619, collagen, epinephrine, ADP, TRAP-6).
- Platelets were pre-incubated with inhibitors including acetylsalicylic acid (ASA), SQ-29,548, apyrase, PSB-0739, and eptifibatide.
- PMPs were quantified using flow cytometry with CD61 and annexin-V markers.
Main Results:
- Platelet agonists induced annexin V-positive PMP shedding, with high-dose collagen showing the strongest response.
- Acetylsalicylic acid (ASA) significantly reduced PMPs induced by arachidonic acid, collagen, and TRAP-6, but not epinephrine or ADP.
- Apyrase, SQ-29,548, and PSB-0739 also inhibited PMP generation, suggesting roles for ADP and specific receptor pathways.
- Eptifibatide abolished agonist-induced PMP release, except for high-dose collagen.
- Thromboxane A2 generation and ADP secretion act as amplifiers of PMP shedding.
Conclusions:
- Platelet agonists stimulate PMP shedding through pathways involving thromboxane A2 and ADP.
- Antiplatelet drugs, particularly ASA, effectively inhibit PMP generation.
- The fibrinogen and collagen receptors play critical roles in PMP generation, independent of platelet aggregation.
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