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Platelet dynamics in blood flow
Published in Annie Viallat, Manouk Abkarian, Dynamics of Blood Cell Suspensions in Microflows, 2019
Jawaad Sheriff, Danny Bluestein
The level of platelet activation under flow conditions has been defined as the percentage of β-thromboglobulin released from the α granules [233], percentage of serotonin released from the dense granules [84], or the rate of thrombin generated on the platelet surface [98, 99]. The latter is correlated with the shear “dose” - an accumulation of the shear stress and exposure time during platelet circulation through physiological and pathological conditions [13, 138, 163, 194, 205]. The Lagrangian stress accumulation history of platelets typically is presented in a power law form, with varying contributions of shear stress and exposure time, and is simplified into a linear form for computational fluid dynamics (CFD) simulations [138].
Kinetic study of NTPDase immobilization and its effect of haemocompatibility on polyethylene terephthalate
Published in Journal of Biomaterials Science, Polymer Edition, 2019
Balaji Ramachandran, Vignesh Muthuvijayan
Heparin is one of the widely studied bioactive molecules on various material surfaces to improve haemocompatibility [5]. Despite heparin-mediated inhibition of thrombin formation, researchers have explored the inhibition of early stages of thrombus formation through inhibiting platelet activation. Upon adhesion to the foreign material surfaces, platelets can lead to activation and release of pro-coagulant agonists from dense granules such as thromboxane A2, ADP, serotonin [6]. For platelet-specific improvement of haemocompatibility of material surfaces, many molecules such as nitric oxide, dipyridamole, hirudin had been explored [7,8]. Apyrase/ecto-nucleoside triphosphate diphosphohydrolase (E-NTPDase/CD39) is also one such molecule which can be used for enhancing haemocompatibility of the material surface [9,10]. NTPDase is an important transmembrane protein that phosphohydrolyses ATP to ADP and then to AMP, thereby regulating ADP-dependent platelet activation and adhesion [11,12]. Coating of modified apyrase on the material surface shows improved blood compatibility [13,14]. Clinical studies showed that the platelet adhesion and activation vary between healthy individuals and patients with cardiovascular artery disease [15]. Hence, the coating of the NTPDase should be based on the end user application. This can be only achieved by studying the kinetics of the attached biomolecules.