Testing agonist-induced platelet aggregation by the Impact-R [Cone and plate(let) analyzer (CPA)]

Abstract

The Impact-R [Cone and plate(let) analyzer (CPA)] is useful to assess platelet adhesion in different diseases and to monitor antiplatelet therapy. The purpose of the present study was to adapt this system to test agonist-induced platelet aggregation. Blood samples were tested by light transmission platelet aggregometry (LTA), Impact-R regular test and Impact-R agonist-response test. In the latter, samples were pre-incubated for 1 min with an agonist leading to platelet activation, micro-aggregates formation and reduced adhesion. Impact-R regular test of ten healthy volunteers demonstrated platelet adhesion (surface coverage, SC) of 11.2 +/- 2.6% while LTA induced by ADP, ristocetin, epinephrine, collagen and arachidonic acid (AA) yielded maximal aggregation (81% to 93%). In the Impact-R agonist-response test, SC was reduced to 2.2 +/- 1.0%, 1.2 +/- 0.9%, 2.3 +/- 1.0%, 2.2 +/- 0.8% and 2.4 +/- 0.4%, respectively. Prostaglandin E(1) treatment weakened SC reduction in response to ADP and epinephrine (SC of 8.8 +/- 1.8% and 9.5 +/- 2.0%, respectively). Inhibition of P2Y(12) receptor with 2MeSAMP resulted in a dose-dependent decrease in maximal aggregation in the ADP-induced test, which inversely correlated to SC in the Impact-R ADP-response test. The Impact-R agonist-response tests detected aggregation defects in patients with storage pool disease, severe von Willebrand disease and epinephrine response deficiency, and may be useful to assess the effect of different agonists on platelet aggregation.

Thrombin-inducible platelet adhesion and regulation of the platelet seven-transmembrane thrombin receptor-1 (PAR-1): Effects of unfractionated heparin and lepirudin

“…Even though the increase was small it was significant, while no such change were observed with lepirudin. Activated platelets are likely to form microaggregates under high shear conditions, which results in a reduction of platelet adherence [13]. However, the minimal platelet activation was not discernible by the cone and plate analyzer.…”

“…The Impact-R is a commercially available development of the cone and plate analyzer. This device allows evaluation of platelet adhesion and aggregation under close to physiologic conditions in a wholeblood assay [13]. In brief, 130 mL of trisodium citrate-anticoagulated whole blood was placed on the polystyrene plate.…”

“…Thrombin-inducible platelet adherence was tested in the presence of GPRP, using the Impact-R aggregation test [13]. Alpha-thrombin (1.25 U/ml; Sigma-Aldrich) was added to the blood and shear stress was applied after 1 minute incubation, like in the screening test.…”

Ocena funkcji płytek krwi u pacjentów z endogenną hiperkortyzolemią

“…In this method, the closure time (CT) of an aperture containing a nitrocellulose membrane coated with platelet agonists is measured. ADP and collagen or collagen and epinephrine (EPI) are agonists that activate platelets in this method [24]. The measure of platelet function in the PFA system reflects their adhesion and aggregation in full blood.…”

“…Laminar flow over polystyrene surface of the wall is achieved according to the Cone and Plate principle [24,25]. Results are expressed as percentage of surface covered (SC) by platelets and average size (AS) of the adherent particles in μm 2 [24]. Tests here were performed using DiaHem (Switzerland) kit and reagents (DiaMed Impact-R test kit).…”