Platelet aggregation impacts thrombin generation assessed by calibrated automated thrombography

Abstract

A calibrated automated thrombogram (CAT) is performed usually with human platelet-free plasma (PFP) but may be more relevant with platelet-rich plasma (PRP). In this case, platelets are not stimulated by subendothelial molecules like collagen. Our aim was to assess the consequence of strong (collagen) or weak (ADP) induction of platelet release and aggregation on thrombin generation. Platelet aggregation in PRP was triggered with 10 µg/mL collagen or 10 µM ADP using a lumi-aggregometer. Thrombin generation curves were monitored by CAT in different conditions: PRP, PRP with activated platelets (actPRP), aggregated PRP (agPRP), aggregated platelets resuspended in autologous PFP (resPRP), PFP and PFP obtained after aggregation (agPFP). We found a 3-fold shortening of the lag time and time to peak and a marked increase in velocity and thrombin peak without changes in endogenous thrombin potential (ETP) in agPRP with both agonists compared with PRP. The same holds true in agPFP but with a marked increase in ETP compared with PFP. Similar changes in the kinetics of thrombin generation were observed with actPRP-collagen and to a lesser extent in resPRP-collagen compared with PRP. By contrast, there were no modifications of the thrombin generation curves in actPRP-ADP. Alpha-2-macroglobin-thrombin complexes were unchanged in the different PRP conditions but were increased in PFP prepared from agPFP compared to control PFP. Platelet aggregation during activation by agonists other than thrombin did not increase thrombin generation but accelerated its kinetics mainly via platelet content release and platelet-derived extracellular vesicules formation. In diseases characterized by altered platelet granule content or release as well as altered platelet activation, a platelet aggregation step prior to CAT analysis may be clinically relevant to improve laboratory estimation of the bleeding/thrombotic balance.

Thrombin generation abnormalities in Quebec platelet disorder

“…We found that QPD is associated with significant PRP but not PPP TG abnormalities, with strong associations between QPD platelet (but not plasma) FV levels and QPD PRP ETP and peak thrombin concentration. Interestingly, platelet-activating agonists improved PRP TG, as anticipated, 29 without accentuating the QPD PRP TG defect.…”

Rivaroxaban Effects Illustrate the Underestimated Importance of Activated Platelets in Thrombin Generation Assessed by Calibrated Automated Thrombography

“…Platelet aggregation was triggered by 2 µg/mL equine collagen fibrils type I (Chrono-log Corp, Havertown, PA, USA). Aggregated PRP was used directly after aggregation for CAT measurement [14].…”

“…In the present work, we aimed to explore the origin and determinants of camel-back shaped TG curves in the presence of new oral anticoagulants, in particular rivaroxaban. We took advantage of the use of aggregated platelet rich plasma (PRP/agPRP) in the CAT [14] which fully includes platelet procoagulant activity since modified TG kinetics in particular faster TG could compensate the slow TG often observed after rivaroxaban treatment.…”

Human Cancer and Platelet Interaction, a Potential Therapeutic Target

“…Clinical evidence and mouse models demonstrate that platelet-cancer cell interaction is crucial for cancer metastasis [ 23 ]. Platelets, originally derived from megakaryocytes in the bone marrow [ 24 ], are the key regulator of thrombosis [ 25 , 26 ]. The major function of platelets is to prevent bleeding and reduce blood loss in case of vascular injury [ 27 ].…”