New abstract created on Tuesday September 29, 2015 Immobilization of a novel anti-thrombotic drug on a metallic vascular stent

Abstract

Event Abstract Back to Event New abstract created on Tuesday September 29, 2015 Immobilization of a novel anti-thrombotic drug on a metallic vascular stent Nicolas Bricout1, Jonathan Sobocinki1, 2, Adrien Hertault1, 2, William Laure3, Feng Chai1, Stéphan Haulon1, 2, Joel Lyskawa3 and Nicolas Blanchemain1 1 University of Lille, INSERM U1008 - Biomaterial Research Group, France 2 CHU de Lille, Aortic centre, Vascular Surgery, France 3 University of Lille, UMET, CNRS UMR 8207 Polymer Systems Engineering, France Introduction: In-stent restenosis (ISR) is promoted by platelet aggregation and thrombus formation occurring after stent implantation[1]. Drug-eluting stents have reduced the rate of ISR, but are associated with high risk of late acute stent thrombosis. Highly bioadhesive polydopamine (PDA) coating on Chromium-Cobalt (CrCo) substrate represents an interesting platform, which enables the immobilization of various relevant drugs promoting vascular wall healing[2] and may also directly improve endothelial cells proliferation[3]. This study aimed at developing and optimizing a PDA-coated CrCo stent functionalized with EP (224283, Endotis Pharma SA), a molecule that combines GPIIbIIIa antagonist and factor Xa inhibitor to reduce acute thrombosis and ISR[4]. Materials and Methods: CrCo substrates were coated by PDA as previously reported[3], and immersed in a polyethylenimine solution (PEI, pH8.5) overnight to react with PDA (by Michael addition and Schiff base reaction) in order to increase the amount of amine functions on the surface. This PDA-PEI coating enabled covalent immobilization of N-hydroxysuccinimide Biotin[5]. This key step permitted Avidin immobilization (via its high affinity for biotin), which can further interact with the biotin moiety of EP. The amount of amino groups formed on the PDA-coated surface before and after PEI addition was determined by orange acid II (OAII) colorimetric titration. Surface of samples was further characterized by Surface Plasmon Resonance (SPR) and Scanning Electron Microscopy (SEM). Cytocompatibility of functionalized surface was evaluated with human umbilical vein endothelial cells (HUVECs). The antithrombotic and antiplatelet activities of samples were evaluated by anti-factor Xa (anti-Xa) assay, lactate dehydrogenase (LDH) assay and SEM, respectively. Degradation kinetics of the EP-functionnalized samples in phosphate buffered saline (PBS) was studied under semi-dynamic condition and evaluated by monitoring anti-Xa activity. Results: OAII assay proved a significant increase in amino groups available on PDA-PEI surface (36.0 nM/cm2) compared to PDA ones (10.4 nM/cm2). The successive grafting of PEI, Biotin, and Avidin on PDA-coated samples was well evidenced by SPR (Figure 1) and SEM. Moreover, the immobilized EP on functionalized substrates exhibited a higher anti-Xa activity ( >1.81 U/mL) than that of control (0.09 U/mL), as depicted in Figure 2. These findings highlighted that EP was effectively grafted on the functionalized CrCo surface and preserved its biological activity. No alterations of HUVECs cell vitality were found on EP-functionalized samples. Degradation property of functionalized surface is under study. Conclusions: This study developed an innovative grafting process of an antithrombotic and antiplatelet molecule - EP(224283) on a PDA/PEI-coated CrCo via Biotin-Avidin interaction. This functionalized stent may offer a promising solution to reduce ISR and late acute thrombosis. AbbottVascular (Santa Clara, CA., USA) for providing vascular stents used for the purpose of the study; Endotis Pharma SA for generous supply of the EP224283; Alexandre Ung for his kind help in haematological analysis; French Society of Radiology (SFR) for providing financial support to this project