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3‐O Sulfation of Heparin is Required for Hepatic Accumulation
Author(s) -
Harris Edward N,
Liu Jian,
Miller Colton,
Xu Yongmei,
Blank Emma
Publication year - 2016
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.30.1_supplement.943.3
Subject(s) - heparin , sulfation , fondaparinux , chemistry , glucuronic acid , low molecular weight heparin , pharmacology , biochemistry , thrombosis , medicine , polysaccharide , surgery , venous thromboembolism
Heparin is the most common and widely used anti‐coagulant in use for surgery, dialysis, and treatment of thrombosis. Heparin, which is a polysaccharide composed of glucuronic/iduronic acid and N‐acetylglucosamine sugars that are highly sulfated, comes in three forms: unfractionated heparin (UFH) having a polydispersity of 3000–30,000 Da, low‐molecular weight heparin (2000–8000 Da), and the synthetic pentasaccharide, Fondaparinux. Due to size, UFH accumulates in liver, is degraded and then filtered out by the kidneys. In contrast, LMWHs do not accumulate in liver and are eliminated by the kidneys, thus, LMWHs may not be suitable for renal impaired patients. LMWHs are the most commonly prescribed form of the drug since it may be self‐injected by the patient at home for post‐surgical treatment. Since heparin comes from a porcine source, its availability is dependent on a healthy swine herd. The side‐effects of heparin include bleeding and heparin‐induced thrombocytopenia (HIT) which affects 2–4% of patients. The development of synthetic heparins will potentially eliminate dependence on the swine source and the monodisperse preparations will give the physician more control over the side‐effects. In this study, we used a monodisperse dodecamer (12mer) LMWH with and without specific 3‐O sulfation. Methods 4–6 week old CD‐1 mice were subcutaneously injected with 1 mg/kg of either 35 S‐12mer (containing one 3‐O sulfation) or 35 S‐n12mer (not containing 3‐O sulfation) and placed in metabolic cages for a duration of up to 26 hrs. Urine was collected at various times during the incubation phase. At each time point, mice were anesthetized and blood, liver, and kidney tissue was collected and evaluated for content of the radiolabeled material. Results The n12mer had a shorter half‐life in blood and was excreted faster than the 12mer. The hepatic accumulation of the n12mer was low and brief, suggesting that the polymer briefly bound to the sinusoidal endothelial cells due to static charge rather than being internalized by receptors. In contrast, the 12mer had a much higher and longer duration in the liver and the amount in urine was lower and more prolonged. Degradation of the 12mer was also higher in the urine in the 3–7 hr range post‐injection, whereas, most of the n12mer was still intact. Conclusion Synthetic 12mer containing 3‐O sulfation, which represents only a 6% increase in overall charge of the polymer, binds to specific receptors (Stabilin‐2/HARE) in the liver sinusoidal endothelium and is degraded before release in the blood and filtered out by the kidneys. Support or Funding Information NIH/NHLBI 5R01HL094463‐07