Platelet aggregation impacts thrombin generation assessed by calibrated automated thrombography

Area of Science:

• Hemostasis and Thrombosis
• Platelet Physiology
• Clinical Laboratory Science

Background:

• Calibrated automated thrombogram (CAT) is typically performed with platelet-free plasma (PFP).
• Platelet-rich plasma (PRP) analysis may offer greater clinical relevance, as platelets are not stimulated by subendothelial molecules like collagen in PFP.
• The impact of platelet activation and aggregation on thrombin generation kinetics in PRP requires further investigation.

Purpose of the Study:

• To assess the effect of strong (collagen) or weak (ADP) platelet activation and aggregation on thrombin generation.
• To compare thrombin generation in various platelet-rich and platelet-free plasma conditions.

Main Methods:

• Platelet aggregation was induced in PRP using collagen (10 µg/mL) or ADP (10 µM) and measured with a lumi-aggregometer.
• Thrombin generation curves were monitored using CAT in PRP, activated PRP (actPRP), aggregated PRP (agPRP), aggregated platelets resuspended in autologous PFP (resPRP), PFP, and aggregated PFP (agPFP).

Main Results:

• Platelet aggregation significantly shortened lag time and time to peak thrombin, increased velocity and peak thrombin in agPRP (collagen and ADP) compared to PRP.
• Aggregated PFP (agPFP) showed increased endogenous thrombin potential (ETP) compared to PFP.
• Platelet aggregation accelerated thrombin generation kinetics via platelet content release and extracellular vesicle formation, without altering thrombin generation in activated PRP with ADP.

Conclusions:

• Platelet aggregation, induced by agonists like collagen or ADP, accelerates thrombin generation kinetics but does not necessarily increase the overall potential.
• The formation of platelet-derived extracellular vesicles plays a key role in this kinetic acceleration.
• Incorporating a platelet aggregation step prior to CAT analysis may enhance the laboratory assessment of bleeding and thrombotic risks in specific clinical conditions.