Combined Use of Polycarboxybetaine Coatings with a Selective FXIIa Inhibitor to Create Potent Biomaterial Anticoagulation Without Bleeding During Extracorporeal Life Support

摘要 在美国，每年有超过19万人患有急性呼吸窘迫综合征， 从30-40%的最佳治疗。此外，还有超过1200万慢性肺病患者， 6.9百万次急诊，超过18万人死亡。当机械通气不足以 为了支持这些患者，将皮质外膜氧合（ECMO）用作恢复的桥梁或 移植。不幸的是，ECMO受到出血和血栓并发症的困扰， 存活率分别约为40%和33%。混凝的原因主要是表面吸附 血浆蛋白、凝血级联的内在分支的后续激活和血小板结合 吸附纤维蛋白原。这是对抗使用全身，静脉肝素，但这抑制了两个生物材料- ECMO回路中的诱导凝血和患者组织中的组织因子诱导凝血， 出血并发症为了同时消除这两个问题，我们建议将联合收割机 选择性地抑制血液-生物材料界面处的凝结同时留下基于组织的 凝固完好。第一种是用两性离子聚羧基甜菜碱（PCB）涂覆生物材料表面。我们最初 结果表明，PCB涂层在体外显著降低了蛋白质吸附和血小板结合 以及绵羊体外膜肺氧合过程中的长期血凝块形成第二个是FXII 900，一种有效的，高选择性的双环 肽FXIIa抑制剂。FXII 900在纳摩尔浓度下抑制表面诱导的凝血激活 而不影响凝固级联的基于组织的外部分支或共同分支。在我们 初步，短期兔ECMO研究，我们证明，与标准相比， 临床肝素抗凝。同时，FXII 900 plus PCB保持正常出血时间， 肝素使出血时间增加到正常的2.9倍。该提案的目标是扩大这一点， 通过i）证明PCB + FXII 900组合的有效性， 5天体内体外生命支持期间的抗凝和ii）开发长效FXII 900 这些制剂能够每8或12小时推注给药，而不是连续静脉滴注。如果成功， 这些研究将导致临床抗凝策略，i）减少出血和血栓形成， ECMO期间的并发症，ii）降低ECMO死亡率，以及iii）简化ECMO的临床应用。这些 当这些益处结合在一起时，也可能允许在重症监护病房外安全地长期使用ECMO。

Abstract Over 190,000 people suffer from acute respiratory distress syndrome in the US each year, with mortality rates from 30-40% with the best treatment. In addition, there are over 12 million patients with chronic lung disease, 6.9 million emergency room visits, and over 180,000 deaths. When mechanical ventilation is insufficient to support these patients, extra-corporeal membrane oxygenation (ECMO) is used as a bridge to recovery or bridge to transplantation. Unfortunately, ECMO is plagued by bleeding and thrombotic complications that reduce patient survival by approximately 40 and 33%, respectively. The cause of coagulation is primarily surface adsorption of plasma proteins, subsequent activation of the intrinsic branch of the coagulation cascade, and platelet binding to adsorbed fibrinogen. This is combated using systemic, intravenous heparin, but this inhibits both biomaterial- induced coagulation in the ECMO circuit and tissue-factor induced coagulation in the patient’s tissues, resulting in bleeding complications. To eliminate both of these problems simultaneously, we propose to combine two means of selectively inhibiting coagulation at the blood-biomaterial interface while leaving tissue-based coagulation intact. The first is biomaterial surface coating with zwitterionic polycarboxybetaine (PCB). Our initial results demonstrate that the PCB coating dramatically decreases protein adsorption and platelet binding in vitro and long-term clot formation during sheep ECMO. The second is FXII900, a potent, highly-selective bicyclic peptide FXIIa inhibitor. FXII900 inhibits surface-induced activation of coagulation at nanomolar concentrations without affecting the tissue-based extrinsic branch or common branch of the coagulation cascade. In our preliminary, short-term rabbit ECMO studies, we demonstrate a 94% reduction in clot formation vs. standard clinical heparin anticoagulation. At the same time, FXII900 plus PCB maintained a normal bleeding time, while the heparin increased the bleeding time to 2.9 times normal. The goals of this proposal are to extend this technology toward clinical applications by i) proving the effectiveness of combined PCB plus FXII900 anticoagulation during 5-day in vivo extracorporeal life support and ii) developing long-acting FXII900 formulations that enable bolus dosing every 8 or 12 hours rather than a continuous intravenous drip. If successful, these studies would lead to a clinical anticoagulation strategy that i) reduces bleeding and thrombotic complications during ECMO, ii) reduces ECMO mortality, and iii) simplifies clinical application of ECMO. These benefits, when combined, might also allow safe long-term ECMO outside the intensive care unit.