Thromboresistant Polymers Via Catalytic Generation of NO

描述（由申请人提供）：拟定了旨在制备、表征和测试能够从血液中内源性S-亚硝基硫醇（RSNO）物质催化生成一氧化氮（NO）的新型聚合物材料的体内抗血栓性/生物相容性的持续研究。I期研究的结果表明，用给定的Cu（II）-络合物以及有机硒（RSe）物种修饰的聚合物能够在浸泡在含有5 M水平的RSNO的溶液中时产生生理相关水平的NO，所述RSNO的浓度在新鲜血液中发现。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/血液界面处局部产生NO应显著降低聚合物涂覆的医疗装置（包括支架、血管移植物、植入的导管和传感器）表面上血栓形成的风险，正在进行的努力（包括本项目第一阶段和其他研究的结果）已经清楚地表明，较早开发的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上的血栓形成。我们的第二阶段目标现在将集中于：1）进一步合成具有共价连接的Cu（II）-大环草胺络合物作为催化位点的生物医学级聚氨酯（PU）阵列，以及制备/评估具有嵌入的CuO微米/纳米颗粒的PU，其也可以从RSNO产生NO; 2）开发将RSe催化位点连接到PU的方法，并研究新的逐层（LbL）在任何生物医学聚合物或器件表面上覆盖RSe位点的化学沉积方法（包括钛和不锈钢）; 3）研究（1）和（2）中设计的聚合物涂层在与各种RSNO物质接触时催化产生NO的能力，以及评估作为时间函数的催化NO生成的变化（由于催化位点浸出、中毒等）; 4)用小动物（小鼠和兔）使用标准ISO方案检查新的Cu和RSe基涂层的毒性;和5）在外周血管移植物的猪动物模型中测试最有前途的新的NO生成涂层的长期体内抗血栓性，所述外周血管移植物由辛辛那提大学医学院的合作者开发。我们预计，本申请中描述的研究将产生各种新型仿生材料，这些材料将立即用于制备/涂覆许多医疗植入物以降低体内血栓形成的风险。公共卫生相关性：在生物医学领域中，非常需要新型聚合物涂层，所述新型聚合物涂层可以增强广泛的医疗装置的生物相容性和功能性，所述医疗装置包括导管、血管移植物、支架、体内化学传感器、体外回路等。在这些血液的表面上存在威胁生命的血栓形成的挥之不去的风险，接触对接受此类干预的患者仍有严重危害的器械。拟议的研究将通过为设备制造商提供新的涂层来产生直接影响，这些涂层可以通过自发产生一氧化氮（一种有效的抗血小板剂）来防止在医疗植入物表面形成凝块，这些物质来自已经存在于血液中的内源性S-亚硝基硫醇物质。

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.