Thromboresistant Polymers Via Catalytic Generation of NO

描述（由申请人提供）：建议继续研究旨在制备，表征和测试能够从血液中内源性S-亚硝基硫醇（RSNO）物种催化生成一氧化氮（NO）的新型聚合物材料的体内血栓电阻率/生物相容性。I期研究的结果表明，用给定的Cu（II）复合物修饰的聚合物以及有机硒（RSe）物种，在含有5M水平的RSNOs（新鲜血液中发现的RSNOs浓度）的溶液中浸泡时，能够产生生理上相关水平的NO。此外，使用相同的催化聚合物化学来设计新型电化学RSNO传感器已经产生了响应全血中RSNO浓度的装置，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，一氧化氮是血小板活化和粘附以及平滑肌细胞增殖的有效抑制剂。因此，在聚合物/血液界面处局部生成NO将显著降低聚合物涂层医疗器械（包括支架、血管移植物、植入式导管和传感器等）表面血栓形成的风险。正在进行的研究（包括本项目一期和其他研究的结果）清楚地表明，早期开发的NO释放聚合物以及较新的NO生成聚合物确实抑制了植入装置表面血栓的形成。我们第二阶段的目标现在将集中在：1)进一步合成一系列生物医学级聚氨酯（pu），其共价附着的Cu(II)-环环复合物作为催化位点，以及制备/评估嵌入Cuo微/纳米颗粒的pu，这些微/纳米颗粒也可以从RSNOs中产生NO；2)开发将RSe催化位点附着在pu上的方法，并研究一种新的逐层（LbL）聚电解质沉积方法，以固定任何生物医学聚合物或设备表面（包括钛和不锈钢）上的RSe位点；3)研究(1)和(2)中设计的聚合物涂层在与各种RSNOs物种接触时催化生成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)采用ISO标准规程，用小动物（小鼠和家兔）检测新型铜和铼基涂层的毒性；5)在由辛辛那提大学医学院的合作者开发的猪周围血管移植动物模型中，测试最有前途的新型NO生成涂层的长期体内血栓抵抗性。我们预计，本申请中描述的研究将导致各种新型仿生材料，这些材料将立即应用于制备/涂层大量医疗植入物，以降低体内血栓形成的风险。公共卫生相关性：生物医学界非常需要新型聚合物涂层，以增强各种医疗器械的生物相容性和功能，包括导管、血管移植物、支架、体内化学传感器、体外电路等。事实上，这些血液接触装置表面存在威胁生命的血栓形成风险，这对接受此类干预的患者来说仍然是一个严重的危险。拟议的研究将立即产生影响，为设备制造商提供新的涂层，可以通过从血液中已经存在的内源性s -亚硝基硫醇中自发产生一氧化氮（一种有效的抗血小板剂）来防止医疗植入物表面形成血栓。

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.