title: Platelet function recovery following exposure to triple anti-platelet inhibitors using an in vitro transfusion model.
abstract: BACKGROUND
  Dual anti-platelet therapy (DAPT) with aspirin and a P2Y12 antagonist is standard of care to reduce risk of thrombosis, but does not directly target thrombin-dependent platelet activation. Therefore, PAR-1 antagonist addition to DAPT (i.e., triple anti-platelet therapy; TAPT) may improve the efficacy of treatment, though at the expense of an increase in bleeding risk. Using an in vitro transfusion model, we evaluated if platelet function loss associated with TAPT can be remedied by the addition of drug-naïve platelets.
  
  
  METHODS
  To mimic TAPT, platelet-rich plasma (PRP) prepared from consented DAPT patients (DPRP) was incubated with a vorapaxar at therapeutic plasma levels (TPRP). To simulate platelet transfusions, TPRP was mixed with increasing proportions of drug-naïve PRP (NPRP). Platelet function recovery was assessed by light transmission aggregometry (LTA), aggregate morphology, and P-selectin expression.
  
  
  RESULTS
  LTA results demonstrated that 20% NPRP was required to restore the ADP aggregation response in TPRP to the response observed in DPRP and 40% NPRP recovered aggregation to >65%. Higher NPRP fractions (60%) were required to restore the platelet reactivity using TRAP-6 (SFLLRN) or arachidonic acid (AA). PAR-4 aggregation was unaffected by platelet antagonists. A decrease in single, free platelets and incorporation of mepacrine-labeled naïve platelets into aggregates occurred with increasing NPRP portions. Upon agonist activation, the surface density and percent of P-selectin positive platelets increased linearly upon addition of NPRP.
  
  
  CONCLUSIONS
  This in vitro model demonstrated that administration of drug-naïve platelets can be a useful strategy for reversing overall platelet inhibition observed with TAPT.
authors.affiliation: CirQuest Labs, Memphis, TN, USA.
authors.forename: Vinay
authors.initials: V
authors.lastname: Bhal
authors.affiliation: CirQuest Labs, Memphis, TN, USA.
authors.forename: Michael J
authors.initials: MJ
authors.lastname: Herr
authors.affiliation: CirQuest Labs, Memphis, TN, USA.
authors.forename: Mason
authors.initials: M
authors.lastname: Dixon
authors.affiliation: Sutherland Cardiology Clinic, Memphis, TN, USA.
authors.forename: Steve
authors.initials: S
authors.lastname: Akins
authors.affiliation: CirQuest Labs, Memphis, TN, USA.
authors.forename: Ed
authors.initials: E
authors.lastname: Hord
authors.affiliation: CirQuest Labs, Memphis, TN, USA.
authors.forename: Melanie M
authors.initials: MM
authors.lastname: White
authors.affiliation: Merck Research Laboratories, Kenilworth, NJ, USA.
authors.forename: Dietmar
authors.initials: D
authors.lastname: Seiffert
authors.affiliation: CirQuest Labs, Memphis, TN, USA.
authors.forename: Jayaprakash
authors.initials: J
authors.lastname: Kotha
authors.affiliation: CirQuest Labs, Memphis, TN, USA.; The University of Tennessee Health Science Center, Memphis, TN, USA.. Electronic address: ljennings@cirquestlabs.com.
authors.forename: Lisa K
authors.initials: LK
authors.lastname: Jennings
mesh_terms: D051017:Apoptosis Regulatory Proteins / Q000187:drug effects; D016718:Arachidonic Acid / Q000378:metabolism; D001241:Aspirin / Q000627:therapeutic use; D001792:Blood Platelets / Q000187:drug effects; D001803:Blood Transfusion / Q000379:methods*; D000077144:Clopidogrel; D005434:Flow Cytometry; D006470:Hemorrhage; D006801:Humans; D007783:Lactones / Q000627:therapeutic use; D019007:P-Selectin / Q000378:metabolism; D010446:Peptide Fragments / Q000378:metabolism; D015539:Platelet Activation / Q000187:drug effects; D010974:Platelet Aggregation / Q000187:drug effects*; D010975:Platelet Aggregation Inhibitors / Q000737:chemistry* / Q000627:therapeutic use; D010979:Platelet Function Tests; D017713:Platelet Transfusion; D058921:Purinergic P2Y Receptor Antagonists / Q000737:chemistry; D011725:Pyridines / Q000627:therapeutic use; D044462:Receptors, Proteinase-Activated / Q000037:antagonists & inhibitors; D058925:Receptors, Purinergic P2Y12 / Q000378:metabolism; D013988:Ticlopidine / Q000031:analogs & derivatives / Q000627:therapeutic use
chemical_list: D051017:Apoptosis Regulatory Proteins; D007783:Lactones; D019007:P-Selectin; C548576:P2RY12 protein, human; D010446:Peptide Fragments; D010975:Platelet Aggregation Inhibitors; D058921:Purinergic P2Y Receptor Antagonists; D011725:Pyridines; D044462:Receptors, Proteinase-Activated; D058925:Receptors, Purinergic P2Y12; C101296:prostate apoptosis response-4 protein; C082835:thrombin receptor peptide (42-47); D016718:Arachidonic Acid; D000077144:Clopidogrel; D013988:Ticlopidine; D001241:Aspirin; C530299:vorapaxar
keywords: Aspirin;; Clopidogrel;; Platelet aggregation;; Platelet transfusion; Vorapaxar;