Prothrombotic activity of cytokine-activated endothelial cells and shear-activated platelets in the setting of ventricular assist device support

BACKGROUND: We systematically analyzed the synergistic effect of: (i) cytokine-mediated inflammatory activation of endothelial cells (ECs) with and (ii) shear-mediated platelet activation (SMPA) as a potential contributory mechanism to intraventricular thrombus formation in the setting of left ventricular assist device (LVAD) support. METHODS: Intact and shear-activated human platelets were exposed to non-activated and cytokine-activated ECs. To modulate the level of LVAD-related shear activation, platelets were exposed to shear stress patterns of varying magnitude (30, 50, and 70 dynes/cm(2), 10 minutes) via a hemodynamic shearing device. ECs were activated via exposure to inflammatory tumor necrosis factor-alpha (TNF-alpha 10 and 100 ng/ml, 24 hours), consistent with inflammatory activation recorded in patients on LVAD circulatory support. RESULTS: Adhesivity of shear-activated platelets to ECs was significantly higher than that of intact/unactivated platelets, regardless of the initial activation level (70 dynes/cm(2) shear-activated platelets vs intact platelets: +80%, p < 0.001). Importantly, inflammatory activation of ECs amplified platelet prothrombinase activity progressively with increasing shear stress magnitude and TNF-a concentration: thrombin generation of 70 dynes/cm(2) shear-activated platelets was 2.6-fold higher after exposure and adhesion to 100 ng/ml TNF-alpha. activated ECs (p < 0.0001). CONCLUSIONS: We demonstrated synergistic effect of SMPA and cytokine-mediated EC inflammatory activation to enhance EC. platelet adhesion and platelet prothrombotic function. These mechanisms may contribute to intraventricular thrombosis in the setting of mechanical circulatory support.Fondazione CARIPLO [2015-1044, 2016-0901]; Regione Lombardia [2016-0901]; National Institutes of Health (NIH Cardiovascular Biomedical Engineering Training Grant) [T32 HL007955]; National Institute of Biomedical Imaging and Bioengineering (Quantum Grant Award) [5U01EB012487-00]; Arizona Center for Accelerated Biomedical Innovation/Tech Launch Arizona [15-035]12 month embargo; published online: 18 February 2019This item from the UA Faculty Publications collection is made available by the University of Arizona with support from the University of Arizona Libraries. If you have questions, please contact us at repository@u.library.arizona.edu