On the Use of the Platelet Activity State Assay for the In Vitro Quantification of Platelet Activation in Blood Recirculating Devices for Extracorporeal Circulation

Abstract

Abstract:We designed an experimental setup to characterize the thrombogenic potential associated with blood recirculating devices (BRDs) used in extracorporeal circulation (ECC). Our methodology relies on in vitro flow loop platelet recirculation experiments combined with the modified-prothrombinase platelet activity state (PAS) assay to quantify the bulk thrombin production rate of circulated platelets, which correlates to the platelet activation (PA) level. The method was applied to a commercial neonatal hollow fiber membrane oxygenator. In analogous hemodynamic environment, we compared the PA level resulting from multiple passes of platelets within devices provided with phosphorylcholine (PC)-coated and noncoated (NC) fibers to account for flow-related mechanical factors (i.e., fluid-induced shear stress) together with surface contact activation phenomena. We report for the first time that PAS assay is not significantly sensitive to the effect of material coating under clinically pertinent flow conditions (500 mL/min), while providing straightforward information on shear-mediated PA dynamics in ECC devices. Being that the latter is intimately dependent on local flow dynamics, according to our results, the rate of thrombin production as measured by the PAS assay is a valuable biochemical marker of the selective contribution of PA in BRDs induced by device design features. Thus, we recommend the use of PAS assay as a means of evaluating the effect of modification of specific device geometrical features and/or different design solutions for developing ECC devices providing flow conditions with reduced thrombogenic impact.

Platelet activation is a preoperative risk factor for the development of thromboembolic complications in patients with continuous‐flow left ventricular assist device

“…Over the last few years, the PAS assay has been utilized extensively for in vitro pre‐clinical studies of device‐associated SMPA . However, no studies have utilized the PAS assay for monitoring SMPA in the clinical setting.…”

“…The platelet activity state (PAS) assay is a unique assay that has been developed specifically to assess SMPA. In previous pre‐clinical studies, we reported that PAS assay is a sensitive tool to monitor in vitro the progression of SMPA over consecutive/cyclic exposure of platelets to haemodynamic hypershear stress patterns pertinent to mechanical blood therapeutic recirculating devices, such as prosthetic heart valves, blood oxygenators, LVADs, and the total artificial heart …”

Microfluidic Approaches for the Assessment of Blood Cell Trauma: A Focus on Thrombotic Risk in Mechanical Circulatory Support Devices

“…In last few years, the PAS assay has been utilized extensively for in vitro studies of PA, characterizing devices and situations with a wide range of imposed shear stress (19,(52)(53)(54)(55)(56)(57)(58)(59), where the non-physiological blood flow patterns mediate the platelets response. The PAS assay has been exploited through three different approaches.…”

Assessment of Thrombelastography and Platelet Life Span in Ovines

“…One of the primary endpoints of preclinical testing of blood contacting cardiovascular devices is to ensure adequate blood biocompatibility . Previously, flow cytometric assays to quantify activated ovine platelets have been reported and shown to be sensitive to blood pump complications and when there was subsequent evidence of thromboembolism .…”