A Novel Self-Renewing Heparin-Binding Anti-microbial Device Surface Coating

描述(由申请人提供)：血栓和感染仍然是任何与血液接触的医疗设备的性能和寿命长期面临的主要挑战。长期的心血管插管，就像血液透析和血管通路一样，在这方面提出了一个重大的临床挑战。值得注意的是，血栓形成和基于感染性生物膜的植入物感染经常密不可分地联系在一起，有效地用治疗药物对抗消退，使感染和血栓形成有增无减。已经发表了许多解决生物材料相关血栓形成的药物和材料方法。然而，很少有人积极寻求组合方法来同时解决血栓形成和感染问题，同时作为生物材料或涂层提供持久的机械弹性。这些观察结果为我们的总体工作假设奠定了基础：一种基于重组蛋白的聚合物含有一个用于遗传编码肝素结合基序的盒，与MaSp2丝蛋白骨架连接在一起，提供了一种“自我更新”的富含肝素的聚合物材料，在表面涂层中既具有血液相容性，又具有抗菌性能。这种生物材料的构建将基于已知的重组丝蛋白表达，与已知的哺乳动物蛋白质的肝素结合模仿相结合，以产生一种新的基于嵌合体的生物材料，它以高亲和力主动结合循环肝素。所提议的医疗器械涂层的制造将根据以下特定目标进行：1)在基于血浆的分析中确定在体外提供非血栓形成和抗微生物活性的ARKAAKA的临界密度。2)确定MaSp2丝基序的临界密度(GGYGPGQGPGGYGPGQGPSGPGSAAAAAAA)n，以提供在血流诱导的剪切应力下具有适当的机械和抗血栓形成性能的血液透析导管表面涂层；3)在受控结构中生产双盒生物聚合物材料，将肝素结合肽(ARKKAAKA)n和MaSp2丝基序(GGYGPGQQGPGGYGPGQGPSGPGSAAAAAAA)n(其中n在特定目标1和2中确定)相结合，以提供机械完整性、血液相容性和微生物抗性。在这项提案的结论中，我们将在血浆、全血或其他生物相关环境中结合严格的肝素结合、抗菌和机械完整性分析，生产并验证一种新型蛋白质血液相容性、抗菌、机械接触血液坚固的表面涂层的耐用性和活性。 公共卫生相关性：改进血液接触和血液透析导管的性能将使数百万患者受益。本提案中描述的方法将寻求通过生产：(1)具有多种控制和设计特征的新型生物聚合物生物材料，(2)从宿主捕获循环肝素的内在能力，(3)可再生的肝素化表面带来的相关血液接触性能好处，(4)使用行业测试标准评估血液透析导管的血栓形成和抗菌性能，以及(5)已知的大规模生产和当前丝质生物材料的成本结构，以满足这一需求。最终，希望将这种新的生物材料快速转化为商业用途，作为目前医疗器械使用的肝素化涂层阵列的替代品。

DESCRIPTION (provided by applicant): Thrombosis and infection remain long-standing major challenges to the performance and longevity of any blood-contacting medical device. Long-term cardiovascular catheterization, as in the context of hemodialysis and vascular access, presents a significant clinical challenge in this regard. Significantly, thrombus formation and infectious biofilm-based implant infection are frequently inextricably connected, effectively countering resolution with therapeutics, allowing infections and thrombosis to proceed unabated. Many pharmaceutical and materials-based methods addressing biomaterial-associated thrombogenesis have been published. Yet few actively seek combinatorial approaches to address both thrombosis and infection simultaneously while concurrently providing durable mechanical resilience as a biomaterial or coating. These observations frame our overall working hypothesis: a recombinant protein-based polymer containing a cassette for genetically encoding heparin-binding motifs, concatenated with a MaSp2 silk protein backbone, provides a "self- renewing" heparin-enriched polymer material, yielding both hemocompatibility and antimicrobial properties in a surface coating. This biomaterial construct will be based on known recombinant silk-based protein expression, combined with known heparin-binding mimicry for mammalian proteins to yield a new chimera-based biomaterial that actively binds circulating heparin with high affinity. Fabrication of the proposed medical device coating will proceed according to the following specific aims: 1) Determine the critical density of ARKKAAKA that provides both non-thrombogenic and antimicrobial activity in vitro in plasma-based assays.; 2) Determine the critical density of the MaSp2 silk motif, (GGYGPGQQGPGGYGPGQQGPSGPGSAAAAAAAA)n, required to provide a hemodialysis catheter surface coating with appropriate mechanical and antithrombogenic properties under blood flow-induced shear stress; 3) Produce a dual cassette biopolymer-based material combining the heparin-binding peptide (ARKKAAKA)n and the MaSp2 silk motif (GGYGPGQQGPGGYGPGQQGPSGPGSAAAAAAAA)n (where n is determined in Specific Aims 1 and 2), in controlled architectures to provide mechanical integrity, hemocompatibility, and microbial resistance. At the conclusion of this proposal, we will have produced and verified the durability and activity of a novel proteinaceous hemocompatible, antimicrobial, mechanically robust blood-contacting surface coating using a combination of rigorous heparin-binding, antimicrobial, and mechanical integrity assays in either plasma, whole blood or another biologically relevant milieu. PUBLIC HEALTH RELEVANCE: Improved performance for blood-contacting and hemodialysis catheters will benefit millions of patients. The approach described in this proposal will seek to address this need by producing: (1) a new biopolymer biomaterial with versatile control and design features, (2) an intrinsic capability to capture circulating heparins from the host, (3) associated blood-contacting performance benefits from renewable heparinized surfaces, (4) assessment of hemodialysis catheter thrombogenic and antimicrobial properties using industry test standards, and (5) known mass production and cost structures from current silk-based biomaterials efforts. Eventually, rapid translation of the new biomaterial to commercial use as an alternative to the array of heparinized coatings in medical device use currently is desired.