Thromboresistant Polymers via Catalytic Generation of NO

描述（由申请人提供）：提出了旨在制备和测试体内血栓电阻率/生物相容性的新型聚合物材料，该材料能够从血液中的内源性亚硝基硫醇物种仿生地产生一氧化氮（NO）。最近在这些实验室中发现，当浸泡在含有亚硝酸盐和/或各种亚硝基硫醇的溶液中时，掺杂某些亲脂性Cu（II）配体复合物的有机聚合物通过催化反应在其界面产生生理相关水平的NO。众所周知，一氧化氮是一种有效的、天然存在的血小板粘附和活化以及平滑肌细胞增殖抑制剂。Pi实验室正在进行的研究已经证明，合成聚合物极大地增强了血栓电阻率，这些聚合物从新型NO加合物（重氮二酸酯）中释放NO，其通量=正常内皮细胞（1 × 10-10 mol/cm2min）。然而，现有的NO释放聚合物用于长期生物医学植入物（例如，作为分流器、移植物、支架等的涂层）的使用受到可以加载在薄聚合物涂层内的相对较小的NO加合物储存器的限制。相比之下，正常血液已经拥有大量亚硝基硫醇形式的一氧化氮前体；由一氧化氮合酶（NOS）产生的内源性NO氧化形成。据信，这些物种可用于在体内具有Cu（II）配合物（环素衍生物）的聚合物界面上产生局部增强的NO水平，该聚合物要么掺杂在某些生物医学级聚氨酯（PU）聚合物中，要么与它们共价相连。血液中的硫酸盐（如谷胱甘肽、半胱氨酸等）和抗坏血酸盐可以很容易地将络合铜（II）还原为Cu(I)。然后Cu(I)能够将亚硝基硫醇还原为NO。该项目的主要目标是制备和检查各种Cu（II/I）配体/聚氨酯材料，这些材料可以进行这种新的氧化还原化学反应，并进一步测试所得到的材料在小动物中的毒性/热原性/炎症反应，以及由辛辛那提大学医学中心的合作研究人员在长期（28 d）的动静脉分流（猪）植入模型中血栓电阻率/生物相容性。如果提出的含有Cu（II）复合物的PU聚合物的体内研究产生了预期的证据，表明由于局部NO生成而减少血栓形成（与对照涂层相比），预计这些新的仿生材料将立即应用于制备/涂层大量生物医学植入物。

DESCRIPTION (provided by applicant): Studies aimed at preparing and testing the in vivo thromboresistivity/biocompatibility of novel polymeric materials capable of biomimetically generating nitric oxide (NO) from endogenous nitrosothiol species in blood are proposed. It has been discovered recently in these laboratories that organic polymers doped with certain lipophilic Cu(II)-ligand complexes generate, via a catalytic reaction, physiologically relevant levels of NO at their interface, when bathed in solutions containing nitrite and/or various nitrosothiols. Nitric oxide is known to be a potent, naturally occurring inhibitor of platelet adhesion and activation as well as smooth muscle cell proliferation. Ongoing studies in the Pi's laboratories have already demonstrated the greatly enhanced thromboresisitivity of synthetic polymers that liberate NO from novel NO adducts (diazeniumdiolates) with fluxes = to normal endothelial cells (1 x 10-10 mol/cm2min). However, use of existing NO release polymers for long-term biomedical implants (e.g., as coatings on shunts, grafts, stents, etc.) is limited by the relatively small reservoir of NO adduct that can be loaded within thin polymeric coatings. In contrast, normal blood already possesses a substantial reservoir of NO precursors in the form of nitrosothiols; formed from the oxidation of endogenous NO produced by nitric oxide synthase (NOS). It is believed that these species can be used to generate locally enhanced NO levels for extended time periods in vivo at the interface of polymers possessing Cu(II) complexes (cyclen derivatives) either doped within or covalently linked to certain biomedical grade polyurethane (PU) polymers. Complexed copper(II) can be readily reduced to Cu(I) by thiolates (e.g., glutathione, cysteine, etc.) and ascorbate in blood. The Cu(I) is then capable of reducing nitrosothiols back to NO. The principal objectives of this program will be to prepare and examine a variety of Cu(II/I)-ligand/polyurethane materials that can carry out this novel redox chemistry and further test the resulting materials for toxicity/pyrogenicity/inflammatory response in small animals, as well as thromboresistivity/biocompatibility in a longer term (28 d) implant model for arteriovenous shunts (in pigs) by co-investigators at the University of Cincinnati Medical Center. If the proposed in vivo studies with PU polymers containing Cu(II) complexes yield the expected evidence of reduced thrombosis (vs. control coatings) due to local NO generation, it is anticipated that these new biomimetic materials would have immediate applications for preparing/coating a host of biomedical implants.