Urokinase-coated chitosan nanoparticles for thrombolytic therapy: preparation and pharmacodynamics in vivo

Blood reperfusion of affected limbs is the most effective therapy for peripheral vascular thrombotic disease, restoring nutrition and blood flow to threatened tissues. Because it is more cost-effective than other thrombolytics, urokinase (UK) is widely used to treat venous thrombosis in China. However, its use is limited because of the risk of UK-related hemorrhagic complications. UK-coated nanoparticles (NPs) may decrease adverse effects while simultaneously increasing thrombolytic benefits. The aim of this study was to combine the sustained-release properties of NPs with the clinical benefits of catheter-directed thrombolysis (CDT) to create a promising new therapy. NPs were prepared via self-assembled chitosan and tripolyphosphate, introduced into a thrombosis model in New Zealand white rabbits, and the ratio of the residual thrombus cross-sectional area to the vascular cross-sectional area was calculated. The NPs had a drug-bearing efficiency of 14.5 ± 1.3 %, an encapsulation efficiency of 94.8 ± 2.1 % while the particle size of UK-coated NPs was 236 nm. Transmission electron microscopy results showed that the shape of the NPs were spherical and regular. Whether delivered by intravenation or catheter, UK-coated NPs produced a significant increase in the thrombolytic effect compared with free UK and confirmed the superiority of CDT for improving clot lysis over drug-induced systemic thrombolysis. The intravenous NPs caused an abnormal increase in fibrinogen. In conclusion, a water-soluble UK-WCS-NP suspension with good encapsulation efficiency was easily prepared UK-WCS-NPs were capable of maintaining UK activity, provided sustained-release of UK and exhibited better thrombolytic function than free UK.