The glycosaminoglycan of recombinant human soluble thrombomodulin affects antithrombotic activity in a rat model of tissue factor-induced disseminated intravascular coagulation.
Previous studies on recombinant human soluble thrombomodulin (rsTM) from Chinese hamster ovary cells revealed that rsTM was expressed as two proteins that differed functionally in vitro due to the presence (rsTM beta) or absence (rsTM alpha) of chondroitin-4-sulfate. The current study evaluates the in vivo behavior of rsTM in rats and in a rat model of tissue factor-induced disseminated intravascular coagulation (DIC). rsTM beta was more potent than rsTM alpha for prolongation of the activated partial thromboplastin time (APTT) and their in vivo half-lives determined by ELISA were 20 min for rsTM beta and 5.0 h for rsTM alpha. Injection of a tissue factor suspension (5 mg/kg) resulted in DIC as judged by decreased platelet counts and fibrinogen concentrations, prolonged APTT, and increased fibrin and fibrinogen degradation products (FDP) levels. A bolus injection of either rsTM (0.2 mg/kg) 1 min before induction of DIC essentially neutralized effects on platelets, fibrinogen, and FDP levels, and had only a moderate effect on APTT prolongation. The dose of anticoagulant to inhibit the drop in platelet counts by 50% (ED50) was 0.2 mg/kg rsTM alpha, 0.07 mg/kg rsTM beta, and 7 U/kg heparin. The effect of increasing concentrations of rsTM and heparin on bleeding times were compared in experiments involving incision of the rat tail. Doubling of the bleeding times occurred at 5 mg/kg rsTM alpha, 3 mg/kg rsTM beta or 90 U/kg heparin. These values represent a 25-fold increase over the ED50 for rsTM alpha, 43-fold for rsTM beta and 13-fold for heparin.(ABSTRACT TRUNCATED AT 250 WORDS)
Nawa
K
K
Research Institute, Daiichi Pharmaceutical Co., Ltd., Tokyo, Japan.
Itani
T
T
Ono
M
M
Sakano
K
K
Marumoto
Y
Y
Iwamoto
M
M
D000818:Animals; D004195:Disease Models, Animal; D004211:Disseminated Intravascular Coagulation / Q000139:chemically induced / Q000503:physiopathology*; D004797:Enzyme-Linked Immunosorbent Assay; D005340:Fibrinogen / Q000378:metabolism; D005342:Fibrinolysis / Q000502:physiology*; D006025:Glycosaminoglycans / Q000502:physiology*; D006470:Hemorrhage / Q000139:chemically induced; D006493:Heparin / Q000493:pharmacokinetics / Q000494:pharmacology; D008297:Male; D010976:Platelet Count; D051381:Rats; D011919:Rats, Inbred Strains; D011956:Receptors, Cell Surface / Q000737:chemistry* / Q000378:metabolism / Q000502:physiology; D018179:Receptors, Thrombin; D011994:Recombinant Proteins / Q000737:chemistry / Q000378:metabolism / Q000502:physiology; D012995:Solubility; D013925:Thromboplastin
D006025:Glycosaminoglycans; D011956:Receptors, Cell Surface; D018179:Receptors, Thrombin; D011994:Recombinant Proteins; D005340:Fibrinogen; D006493:Heparin; D013925:Thromboplastin