Bivalirudin Emulsions Demonstrate Efficacy of a Nanoparticle Strategy for Inhibition and Imaging of Thrombosis

Abstract

A thrombin‐inhibiting perfluorocarbon nanoparticle (PFC NP), functionalized by PPACK (Phe(D)‐Pro‐Arg‐Chloromethylketone), was recently presented as a prototype for a novel class of targeted antithrombotic. Here, a NP functionalized with Bivalirudin (BVR), was compared to BVR and the PPACK NP.PPACK or BVR were covalently attached to PFC NPs. Optical assay verified that PPACK and BVR selectivity and activity against thrombin was not diminished on the NPs. In vivo activity was assessed for PPACK NPs, PPACK, BVR, BVR NPs, heparin, non‐functionalized NPs, or saline in C57BL6 mice subjected to laser injury of the carotid artery. Time to thrombotic occlusion of the injured artery was assessed via Doppler flow measurement. Selected arteries were excised to assess NP retention via 19F magnetic resonance (MR). 3T MRI of thrombosis following administration of PPACK NPs was also demonstrated in cholesterol‐fed rabbits.Previously, PPACK NPs outperformed both heparin (p=.001) and PPACK (p=.0006) in delaying occlusion of the carotid artery. PPACK or non‐functionalized NPs failed to delay occlusion of the carotid artery. BVR NPs significantly delayed occlusion (p=.02) whereas an equivalent dose of free BVR (120 mg/kg) did not (figure 1a). 19F MR captured thrombin‐specific PFC NP retention in occluded arteries of mice (figure 1b) and rabbits (figure 2).