Figure 6. Comparison of the anticoagulant activities of HP and HP-PA-NDs both ex vivo and in vivo.

(a) Ex vivo analysis with aPTT tests for serum extracted from mice treated with normal saline, NDs (2 mg/kg), HP (20 U/kg), and HP-PA-NDs (2 mg/kg) via i.v. injection. Compared to normal saline and ND, HP and HP-PA-ND clearly showed anticoagulant activities (*p < 0.05 and **p < 0.01). The experiments were repeated in triplicate. (b) In vivo analysis for the prevention of thrombus formation with HP and HP-PA-ND in a mouse model of acute thromboembolism. The analysis was made after i.v. injection of normal saline, NDs (2 mg/kg), HP (20 U/kg), and HP-PA-NDs (2 mg/kg) into hindlimb-ischemia mice with thrombosis induced by FeCl₃. At 15 min post-injection, the free HP exhibited almost no anticoagulant activity, as measured by laser Doppler flowmetry. In contrast, the HP-PA-NDs prolonged the blood flow and effectively prevented the thrombus formation up to 40 min post-injection. All the blood flow data were normalized against the corresponding reference flow rates measured for the other hindlimbs of the same mice without surgery and treatments.