Abstract
During open-heart surgery, the status of hemostasis has to be constantly monitored to quickly and reliably detect bleeding or coagulation disorders. In this study, a novel optimized piezo-based measuring system (PIEZ) for rheological monitoring of hemostasis was established. The applicability of the PIEZ for the evaluation of nucleic acid-based drugs influencing coagulation was analyzed. Thrombin aptamers such as NU172 might be used during extracorporeal circulation (ECC) in combination with a reduced heparin concentration or for patients with heparin-induced thrombocytopenia (HIT). Therefore, the effect of the coagulation inhibiting thrombin aptamer NU172 and the abrogation by its complementary antidote sequence (AD) were investigated by this rheological PIEZ system. After the addition of different NU172 concentrations, the coagulation of fresh human blood was analyzed under static conditions and using an in vitro rotation model under dynamic conditions (simulating ECC). The clotting times (CTs) detected by PIEZ were compared to those obtained with a medical reference device, a ball coagulometer. Additionally, after the circulation of blood samples for 30 min at 37 °C, blood cell numbers, thrombin markers (thrombin-antithrombin III (TAT) and fibrinopeptide A (FPA)) and a platelet activation marker (β-thromboglobulin (β-TG)) were analyzed by enzyme-linked immunosorbent assays (ELISAs). The increase of NU172 concentration resulted in prolonged CTs, which were comparable between the reference ball coagulometer and the PIEZ, demonstrating the reliability of the new measuring system. Moreover, by looking at the slope of the linear regression of the viscous and elastic components, PIEZ also could provide information on the kinetics of the coagulation reaction. The shear viscosity at the end of the measurements (after 300 s) was indicative of clot firmness. Furthermore, the PIEZ was able to detect the abrogation of coagulation inhibition after the equimolar addition of NU172 aptamer´s AD. The obtained results showed that the established PIEZ is capable to dynamically measure the hemostasis status in whole blood and can be applied to analyze nucleic acid-based drugs influencing the coagulation.
Highlights
Worldwide, about one million heart surgeries are performed annually, which require extracorporeal circulation (ECC) using the heart-lung machine [1]
The coagulation activation was initiated by the addition of the activators pathromtin and CaCl2 from the activated partial thromboplastin time (aPTT) assay and the change of η0 and η”
These results demonstrated that the piezo-based measuring system (PIEZ) system is capable to measure the coagulation inhibitory measure the coagulation inhibitory effect of NU172 and the abrogation of the aptamer by its effect of NU172 and the abrogation of the aptamer by its complementary antidote sequence (AD) sequence
Summary
About one million heart surgeries are performed annually, which require extracorporeal circulation (ECC) using the heart-lung machine [1]. The ECC includes various methods, such as dialysis, extracorporeal membrane oxygenation (ECMO) for respiratory support, extracorporeal life support (ECLS), and ventricular assist devices (VAD) for cardiac support [2,3,4]. During ECC, the contact of blood with foreign surfaces can lead to life-threatening activation of coagulation. Anticoagulants, such as heparin, are used to prevent coagulation activation. Heparin binds to the enzyme inhibitor antithrombin III (AT) and leads to its activation due to conformational change. The activated AT interacts with the exosite II of thrombin and results in the inactivation of thrombin [5]
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