Thromboresistant Polymers Via Catalytic Generation of NO

描述(由申请人提供)：建议继续进行旨在制备、表征和测试新型聚合物材料的体内血栓抗性/生物相容性的研究，这些材料能够从血液中的内源性S亚硝硫醇(RSNO)催化产生一氧化氮(NO)。第一阶段研究的结果表明，用给定的铜(II)络合物和有机硒(RSe)修饰的聚合物在沐浴在含有5M水平的RSNO的溶液中时，能够产生生理上相关水平的NO，RSNO的浓度是新鲜血液中发现的RSNO浓度。此外，使用相同的催化聚合物化学方法来设计新型的电化学RSNO传感器，已经产生了响应全血中RSNO浓度的设备，进一步证明了这些材料在与血液接触时产生NO的能力。众所周知，一氧化氮是一种有效的抑制血小板活化和黏附以及平滑肌细胞增殖的药物。因此，在聚合物/血液界面局部产生NO应显著降低聚合物涂层医疗设备表面血栓形成的风险，包括支架、血管移植物、植入的导管和传感器等。正在进行的努力(包括本项目第一阶段和其他研究的结果)清楚地表明，早期开发的NO释放聚合物以及较新的产生NO的聚合物确实抑制了植入设备表面的血栓形成。我们第二阶段的目标将集中在：1)进一步合成一系列以共价连接的铜(II)-环络合物为催化中心的生物医用级聚氨酯(PU)，以及制备/评估嵌入CuO微米/纳米粒子的PU，这些微/纳米粒子也可以从RSNO产生NO；2)开发将RSe催化中心附着到PU的方法，并研究一种新的逐层聚电解质沉积方法，以将RSe位置固定在任何生物医用聚合物或器件表面(包括钛和不锈钢)上；3)研究(1)和(2)中设计的聚合物涂层与各种RSNO物种接触时催化产生NO的能力，并评估催化NO生成随时间的变化(由于催化部位浸出、中毒等)；4)使用标准ISO协议通过小动物(小鼠和兔)测试新型铜和RSe涂层的毒性；以及5)在辛辛那提大学医学院合作者开发的猪周围血管移植动物模型上，测试最有希望的新型NO生成涂层的体内血栓形成能力。我们预计，本申请中描述的研究将导致各种新型仿生材料的出现，这些材料将立即应用于制备/涂层一系列医疗植入物，以降低体内血栓形成的风险。与公共卫生相关：生物医学界非常需要新型聚合物涂层，以增强各种医疗设备的生物兼容性和功能性，包括导管、血管移植、支架、体内化学传感器、体外电路等。事实上，这些血液接触设备表面存在危及生命的血栓形成的挥之不去的风险，这仍然是接受此类干预的患者的严重危险。拟议中的研究将产生立竿见影的效果，为设备制造商提供新的涂层，这种涂层可以从血液中已存在的内源性S亚硝硫醇物种中自发产生一氧化氮，防止医疗植入物表面形成凝块。一氧化氮是一种有效的抗血小板药物。

DESCRIPTION (provided by applicant): Continued studies aimed at preparing, characterizing and testing the in vivo thromboresistivity/biocompatibility of novel polymeric materials capable of catalytically generating nitric oxide (NO) from endogenous S- nitrosothiol (RSNO) species in blood are proposed. Results from Phase I studies have demonstrated that polymers modified with given Cu(II)-complexes as well as organoselenium (RSe) species are capable of generating physiologically relevant levels of NO when bathed in solutions containing 5M levels of RSNOs, the concentrations of RSNOs found in fresh blood. In addition, use of the same catalytic polymer chemistries to devise novel electrochemical RSNO sensors has yielded devices that respond to RSNO concentrations in whole blood, further proving the capability of these materials for generating NO when in contact with blood. Nitric oxide is well known to be a potent inhibitor of platelet activation and adhesion as well as smooth muscle cell proliferation. Hence, the local generation of NO at a polymer/blood interface should significantly reduce the risk of thrombus formation on the surface of polymer coated medical devices, including stents, vascular grafts, implanted catheters and sensors, etc. Ongoing efforts (including results from Phase I of this project and other studies) have shown clearly that NO release polymers developed earlier as well as the newer NO generating polymers do inhibit thrombus formation on the surface of implanted devices. Our goals for Phase II will now focus on: 1) further synthesizing an array of biomedical grade polyurethanes (PUs) with covalently attached Cu(II)-cyclen complexes as catalytic sites, as well as preparing/evaluating PUs with embedded Cuo micro/nanoparticles that can also generate NO from RSNOs; 2) developing methods to attach RSe catalytic sites to PUs and also examining a new Layer-by-Layer (LbL) polyelectrolyte deposition method to immobilize the RSe sites on any biomedical polymer or device surface (including titanium and stainless steel); 3) studying the ability of the polymer coatings devised in (1) and (2) for producing NO catalytically when in contact with various RSNOs species, and assessing changes in catalytic NO generation as a function of time (due to catalytic site leaching, poisoning, etc.); 4) examining the toxicity of the new Cu and RSe-based coatings using standard ISO protocols with small animals (mice and rabbits); and 5) testing the longer-term in vivo thromboresistance of the most promising new NO generating coatings in porcine animal model of peripheral vascular grafts developed by collaborators at the University of Cincinnati Medical School. We anticipate that the studies described in this application will lead to a variety of novel biomimetic materials that will have immediate applications for preparing/coating a host of medical implants to reduce the risk of in vivo thrombosis. PUBLIC HEALTH RELEVANCE: There is a great need in the biomedical community for novel polymeric coatings that can enhance the biocompatibility and functionality of a wide range of medical devices including catheters, vascular grafts, stents, in vivo chemical sensors, extracorporeal circuits, etc. Indeed, there exists a lingering risk of life- threatening thrombosis on the surface of these blood-contacting devices that continues to be a serious hazard to patients who receive such interventions. The proposed research will have an immediate impact by providing device manufacturers with new coatings that can prevent clots from forming on the surface of medical implants via spontaneous generation of nitric oxide, a potent anti-platelet agent, from a pool of endogenous S-nitrosothiol species that already exists in blood.