Related Experiment Video
Updated: Jul 17, 2026
Microfluidics in Assessing Platelet Function
Published on: November 8, 2024
Normalization of platelet reactivity in clopidogrel-treated subjects
G Vilahur1, B G Choi, M U Zafar
1Cardiovascular Biology Research Laboratory, Mount Sinai School of Medicine, New York, NY 10029, USA.
Insights
Platelet transfusion can reverse antiplatelet effects of aspirin (ASA) and clopidogrel, potentially reducing surgical bleeding risks. This study quanties the platelet concentrate units needed to restore normal platelet function post-treatment.
Area of Science:
- Cardiovascular Medicine
- Hematology
- Pharmacology
Background:
- Aspirin (ASA) and clopidogrel are standard treatments for acute coronary syndrome (ACS).
- Persistent antiplatelet effects from these drugs can complicate surgical procedures.
- Effective strategies are needed to manage antiplatelet activity before surgery.
Purpose of the Study:
- To investigate the possibility of normalizing platelet reactivity after aspirin (ASA) and clopidogrel treatment.
- To quantify the amount of platelet concentrate required to reverse the antiplatelet effects.
Main Methods:
- Healthy subjects received ASA + clopidogrel loading doses (300 or 600 mg) followed by daily maintenance doses.
- Platelet reactivity was assessed using light transmittance aggregometry (LTA) and flow cytometry.
- Ex vivo transfusion of pooled volunteer platelets (V-PRP) into subject PRP (S-PRP) was used to normalize platelet function.
Main Results:
- At 4 and 72 hours post-treatment, 40% or 50% V-PRP was needed to overcome platelet disaggregation after ADP challenge, depending on the clopidogrel dose.
- An additional 10% V-PRP fully normalized aggregation, with recovery being linear.
- Similar V-PRP amounts normalized platelet function against other agonists like arachidonic acid (AA), collagen, and TRAP.
Conclusions:
- Pre-operative transfusion of 10-12.5 platelet concentrate units may reverse clopidogrel-induced platelet disaggregation, facilitating hemostasis.
- An additional 2.5 units fully normalized platelet function.
- Further in vivo clinical studies are warranted to confirm these findings in patients undergoing surgery.
Background:
Aspirin (ASA) + clopidogrel are commonly used in acute coronary syndrome (ACS), but persistent antiplatelet effects may complicate surgery.
Methods And Results:
To study the possibility of normalizing platelet reactivity after ASA + clopidogrel treatment, 11 healthy subjects received a 325-mg ASA + clopidogrel loading dose (300 or 600 mg dependent on study arm), followed by 81 mg of ASA + 75 mg of clopidogrel daily for 2 days. Platelet reactivity was assessed by light transmittance aggregometry (LTA) [challenged by adenosine diphosphate (ADP), arachidonic acid (AA), collagen, and thrombin receptor activating peptide (TRAP)] and flow cytometry for platelet activation by GPIIb/IIIa receptor exposure pretreatment, 4 and 72 h postload. To normalize platelet reactivity, increasing amounts of pooled platelets from five untreated volunteers [volunteers (V)-platelet-rich plasma (PRP)] were added ex vivo to the subject's PRP (S-PRP). At both 4 and 72 h, 40% and 50% V-PRP were needed to overcome platelet disaggregation in the 300 or 600 mg arms, respectively, after ADP challenge; an additional 10% V-PRP fully normalized aggregation. Recovery of function was linear with each incremental increase of V-PRP. ADP-induced GPIIb/IIIa activation showed the same pattern as LTA (r = 0.74). Forty percent V-PRP was required to normalize platelet function to AA, collagen, and TRAP.
Conclusion:
Our results suggest that the pre-operative transfusion of 10 platelet concentrate units (the equivalent of 40% V-PRP) after a 300-mg clopidogrel loading or 12.5 units (50% V-PRP) after a 600 mg loading may adequately reverse clopidogrel-induced platelet disaggregation to facilitate postoperative hemostasis. An additional 2.5 units fully normalized platelet function. The potential clinical implications of our observations could include shorter hospitalizations and reduced bleeding complications. But these observations should be fully explored in an in vivo clinical setting with clopidogrel-treated patients before and after surgery.
Related Concept Videos
01:20Antiplatelet Drugs: Prostaglandin Synthesis, P2Y12 and Glycoprotein IIb/IIIa Inhibitors
Prostaglandin synthesis inhibitors, exemplified by the widely known aspirin, wield their power by irreversibly acetylating...
01:22Formation of the Platelet Plug
As the injured blood vessel contracts, endothelial cells undergo contraction, revealing collagen fibers in the basement membrane and underlying connective tissue. Furthermore, the plasma membrane of endothelial cells becomes adhesive, preparing the site for platelet adhesion. Platelets...