Elongated plant virus-based nanoparticles for enhanced delivery of thrombolytic therapies.

Thrombotic cardiovascular disease, including acute myocardial infarction, ischemic stroke, and venous thromboembolic disease, is the leading cause of morbidity and mortality worldwide. While reperfusion therapy with thrombolytic agents reduces mortality from acute myocardial infarction and disability from stroke, thrombolysis is generally less effective than mechanical reperfusion and is associated with fatal intracerebral hemorrhage in up to 2-5% of patients. To address these limitations, we propose the tobacco mosaic virus (TMV)-based platform technology for targeted delivery of thrombolytic therapies. TMV is a plant virus-based nanoparticle with a high aspect ratio shape measuring 300 X 18 nm. These soft matter nanorods have favorable flow and margination properties allowing the targeting of the diseased vessel wall. We have previously shown that TMV homes to thrombi in a photochemical mouse model of arterial thrombosis. Here we report the synthesis of TMV conjugates loaded with streptokinase (STK). Various TMV-STK formulations were produced through bioconjugation of STK to TMV via intervening PEG linkers. TMV-STK was characterized using SDS-PAGE and Western blot, transmission electron microscopy, cryo-electron microscopy, and cryo-electron tomography. We investigated the thrombolytic activity of TMV-STK in vitro using static phantom clots, and in a physiologically relevant hydrodynamic model of shear-induced thrombosis. Our findings demonstrate that conjugation of STK to the TMV surface does not compromise the activity of STK. Moreover, the nanoparticle conjugate significantly enhances thrombolysis under flow conditions, which can likely be attributed to TMV's shape-mediated flow properties resulting in enhanced thrombus accumulation and dissolution. Together, these data suggest TMV to be a promising platform for the delivery of thrombolytics to enhance clot localization and potentially minimize bleeding risk.