Department of Pharmacology and Cancer Biology, Duke University, Durham, North Carolina, USA.
Medical Scientist Training Program, Duke University, Durham, North Carolina, USA.
Nat Biotechnol. 2018 Aug;36(7):606-613. doi: 10.1038/nbt.4153. Epub 2018 Jun 4.
Unfractionated heparin (UFH), the standard anticoagulant for cardiopulmonary bypass (CPB) surgery, carries a risk of post-operative bleeding and is potentially harmful in patients with heparin-induced thrombocytopenia-associated antibodies. To improve the activity of an alternative anticoagulant, the RNA aptamer 11F7t, we solved X-ray crystal structures of the aptamer bound to factor Xa (FXa). The finding that 11F7t did not bind the catalytic site suggested that it could complement small-molecule FXa inhibitors. We demonstrate that combinations of 11F7t and catalytic-site FXa inhibitors enhance anticoagulation in purified reaction mixtures and plasma. Aptamer-drug combinations prevented clot formation as effectively as UFH in human blood circulated in an extracorporeal oxygenator circuit that mimicked CPB, while avoiding side effects of UFH. An antidote could promptly neutralize the anticoagulant effects of both FXa inhibitors. Our results suggest that drugs and aptamers with shared targets can be combined to exert more specific and potent effects than either agent alone.
未分级肝素（UFH）是体外循环（CPB）手术的标准抗凝剂，但在存在肝素诱导的血小板减少症相关抗体的患者中，它存在术后出血的风险，且可能有害。为了提高替代抗凝剂 RNA 适体 11F7t 的活性，我们解析了该适体与因子 Xa（FXa）结合的 X 射线晶体结构。发现 11F7t 不结合催化位点表明它可以补充小分子 FXa 抑制剂。我们证明 11F7t 和催化位点 FXa 抑制剂的组合在纯化的反应混合物和血浆中增强了抗凝作用。适体-药物组合在模拟 CPB 的体外氧合器回路中循环的人血液中与 UFH 一样有效地防止了血栓形成，同时避免了 UFH 的副作用。解毒剂可以迅速中和两种 FXa 抑制剂的抗凝作用。我们的结果表明，具有共同靶点的药物和适体可以结合起来，产生比单独使用任何一种药物更特异和更强效的作用。
