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Yu-Bin Liu,1,2 Yun Liu,1,3 Lin Zhang,1 Xing-Chen Zhou,1 Bo-Yuan Ren,1 Can Zheng,1 Chun-Hua Hao,4 Wei-Ting Wang,4 Xia Xia,5 Gang-Qiao Zhou,1,3 Chu-Tse Wu,1 Ji-De Jin1 1Department of Experimental Hematology and Biochemistry, Beijing Institute of Radiation Medicine, Beijing, People’s Republic of China; 2Division of (Bio) Pharmaceutics, Institute of Zhejiang University - Quzhou, Zhejiang, People’s Republic of China; 3School of Medicine, Guizhou University, Guiyang, People’s Republic of China; 4Center for Pharmacodynamic Research, Tianjin Institute of Pharmaceutical Research, Tianjin, People’s Republic of China; 5Beijing SH Biotechnology Co., Ltd., Beijing, People’s Republic of ChinaCorrespondence: Chu-Tse Wu; Ji-de Jin, Email wuct@bmi.ac.cn; jinjide505@163.comBackground: Whether anticoagulant therapy should be used after spinal-cord injury (SCI) surgery was controversial. The anticoagulation characteristics of a newly developed anticoagulant, recombinant neorudin (EPR-hirudin (EH)), were explored using a rat model of SCI to provide a basis for clinical anticoagulation therapy of SCI.Methods: A rat model of SCI was developed by Allen’s method. Then, thrombosis in the inferior vena cava was induced by ligation. The low-bleeding characteristics of EH were explored by investigating dose–response and time–effect relationships, as well as multiple administration of EH, on thrombus formation complicated with SCI.Results: EH inhibited thrombosis in a dose-dependent manner by reducing the wet weight and dry weight of the thrombus. An inhibiting action of EH on thrombosis was most evident in the group given EH 2 h after SCI. After multiple intravenous doses of EH, thrombosis inhibition was improved to that observed with low molecular weight heparin (LMWH) (87% vs 90%). EH administration after SCI neither increased bleeding in the injured spine nor damaged to nerve function. Bleeding duration and activated partial thromboplastin time were increased in the high-dose

Yu-Bin Liu,1 Lin Zhang,1 Xing-Chen Zhou,1 Ying Zhou,1 Yun Liu,1 Can Zheng,1 Xiao Xu,1 Pan-Pan Geng,1 Chun-Hua Hao,2 Zhuan-You Zhao,2 Chu-Tse Wu,1 Ji-De Jin1 1Department of Experimental Hematology and Biochemistry, Beijing Institute of Radiation Medicine, Beijing, 100850, People’s Republic of China; 2Center for Pharmacodynamic Research, Tianjin Institute of Pharmaceutical Research, Tianjin, 300462, People’s Republic of ChinaCorrespondence: Chu-Tse Wu; Ji-De Jin, Department of Experimental Hematology and Biochemistry, Beijing Institute of Radiation Medicine, No. 27 Taiping Road, Beijing, People’s Republic of China, Tel +86 1086-68158312 ; +86 1086-66931425, Email wuct@bmi.ac.cn; jinjide505@163.comIntroduction: Recombinant neorudin (EPR-hirudin, EH) was developed through the addition of an EPR (Glu-Pro-Arg) peptide to the amino terminus of hirudin, which can be recognized and cut by coagulation factors XIa (FXIa) and/or Xa (FXa). In this study, the low-bleeding antithrombotic effects of EH were evaluated utilizing experimental models of thrombosis in rabbits and rats to provide a test basis for clinical trials.Methods: The bleeding risks of EH and hirudin were first compared in mice by the tail-clipping method, and then the antithrombotic activity of EH was investigated in a rabbit model of arteriovenous bypass thrombosis and a rat model of thrombotic cerebral infarction.Results: In mice, intravenous administration of EH at 1.5 mg/kg and 3 mg/kg did not affect the bleeding time compared with normal saline, while the administration of hirudin at 1.5 mg/kg prolonged the bleeding time by over 3 times the administration of normal saline. Furthermore, intravenous administration of EH had a significant dose-dependent inhibitory effect on the formation and development of arteriovenous bypass thrombosis and thrombotic cerebral infarction. Compared with an equimolar dose of hirudin, the antithrombotic effect of EH was similar, while the bleeding si