Construction And Functional Evaluation Of Hirudin Derivatives With Low-bleeding Risk

Although hirudin is better than heparin at preventing recurrent ischemia in patients with unstable angina, hirudin causes more bleeding. Thus, the purpose of this study was to design four derivatives (TH, FH, GH and EH) of hirudin to shut down the bleeding side-effect of hirudin, in which thrombin recognition sites LGPR, FXa recognition sites IEGR, both thrombin and FXa recognition sites GVYAR, and both FXa and FXIa recognition sites EPR were linked to the N-terminal of hirudin respectively for blocking its anticoagulation temporarily. Because the hinidin could be released only at clots where the blood coagulation factors are rich, the derivatives can be used to privent the systemic bleeding complications. The anti-artery thrombosis activities of the derivatives have been studied in a rat model of electrically induced carotid artery injury. In this model, the time to occlusion (TTO) of the derivatives at 4mg/kg dose was almost the same to that of hirudin at 2mg/kg dose, and TT and APTT of the derivatives were only about half of hirudin. In another rat model of inferior vena cava thrombosis, the antithrombotic activity of the derivatives with almost is the same to hirudin at the same dose 0.5mg/kg, while TT and APTT are not increased compared with control. To assess safety, the bleeding time of tail-cut mouse was measured. The bleeding time of derivatives with 6mg/kg dose displayed a statistically significant bleeding effect, which was only a third of hirudin at 1.5mg/kg dose. Thus, the derivatives cause no bleeding at effective doses and show better anti-thrombotic activity than hirudin with the same acceptable bleeding side-effect.