title: In vitro and in vivo characterization of a reversible synthetic heparin analog.
abstract: BACKGROUND
  The global supply of unfractionated heparin (UFH) and all commercially available low molecular weight heparins (LMWH) remain dependent on animal sources, such as porcine intestine or bovine lung. Recent experience has shown that contamination of the supply chain (with over-sulfated chondroitin sulfates) can result in lethal toxicity. Fondaparinux is currently the only commercially available synthetic analog of heparin. We recently described a new class of chemoenzymatically synthesized heparin analogs. One of these compounds (S12-mer) is a dodecasaccharide consisting of an antithrombin-binding moiety with repeating units of IdoA2S-GlcNS6S and two 3-O-sulfate groups that confer the ability to bind protamine.
  
  
  OBJECTIVE
  We sought to further characterize this new compound in vitro using biochemical and global coagulation assays and in vivo using thrombosis and hemostasis assays.
  
  
  RESULTS
  The anticoagulant activities of the Super 12-mer (S12-mer) and Enoxaparin in anti-factor Xa and plasma-based thrombin generation assays were roughly equivalent with a 50% reduction in peak thrombin generation occurring at approximately 325nM. When protamine was titrated against a fixed concentration of S12-mer in plasma or blood, the S12-mer displayed a significant restitution of thrombin generation and clot formation. In vivo, S12-mer inhibited venous thrombosis to a similar extent as Enoxaparin, with similar bleeding profiles.
  
  
  CONCLUSIONS
  These data show that the S12-mer has almost identical efficacy to Enoxaparin in terms of FXa inhibition, while displaying significant reversibility with protamine. Taken together with the ability to ensure purity and homogeneity from batch to batch, the S12-mer is a promising new synthetic heparin analog with a potentially enhanced safety profile.
authors.affiliation: Department of Medicine, The University of North Carolina at Chapel Hill, Chapel Hill, NC, United States; McAllister Heart Institute, The University of North Carolina at Chapel Hill, Chapel Hill, NC, United States.
authors.forename: Matthew F
authors.initials: MF
authors.lastname: Whelihan
authors.affiliation: Department of Pathology and Laboratory Medicine, The University of North Carolina at Chapel Hill, Chapel Hill, NC, United States; McAllister Heart Institute, The University of North Carolina at Chapel Hill, Chapel Hill, NC, United States.
authors.forename: Brian
authors.initials: B
authors.lastname: Cooley
authors.affiliation: Division of Chemical Biology and Medicinal Chemistry, Eshelman School of Pharmacy, The University of North Carolina at Chapel Hill, NC, United States.
authors.forename: Yongmei
authors.initials: Y
authors.lastname: Xu
authors.affiliation: Department of Medicine, The University of North Carolina at Chapel Hill, Chapel Hill, NC, United States; McAllister Heart Institute, The University of North Carolina at Chapel Hill, Chapel Hill, NC, United States.
authors.forename: Rafal
authors.initials: R
authors.lastname: Pawlinski
authors.affiliation: Division of Chemical Biology and Medicinal Chemistry, Eshelman School of Pharmacy, The University of North Carolina at Chapel Hill, NC, United States.
authors.forename: Jian
authors.initials: J
authors.lastname: Liu
authors.affiliation: Department of Medicine, The University of North Carolina at Chapel Hill, Chapel Hill, NC, United States; Department of Pathology and Laboratory Medicine, The University of North Carolina at Chapel Hill, Chapel Hill, NC, United States; McAllister Heart Institute, The University of North Carolina at Chapel Hill, Chapel Hill, NC, United States. Electronic address: Nigel_key@med.unc.edu.
authors.forename: Nigel S
authors.initials: NS
authors.lastname: Key
mesh_terms: D000818:Animals; D000925:Anticoagulants / Q000494:pharmacology; D001777:Blood Coagulation / Q000187:drug effects*; D017984:Enoxaparin / Q000494:pharmacology; D015951:Factor Xa / Q000378:metabolism; D065427:Factor Xa Inhibitors / Q000737:chemistry* / Q000494:pharmacology*; D006493:Heparin / Q000031:analogs & derivatives* / Q000494:pharmacology*; D006494:Heparin Antagonists / Q000494:pharmacology; D006801:Humans; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D011479:Protamines / Q000494:pharmacology; D013917:Thrombin / Q000378:metabolism
chemical_list: D000925:Anticoagulants; D017984:Enoxaparin; D065427:Factor Xa Inhibitors; D006494:Heparin Antagonists; D011479:Protamines; D006493:Heparin; D013917:Thrombin; D015951:Factor Xa