Growth Factor Coated Sutures for Improved Tendon Repair

描述（由申请人提供）：在美国每年因肌腱疼痛就诊的近500万患者中，约有20万人继续进行手术修复。虽然手术修复的症状缓解率很高，但恢复中的患者通常要固定几个月。在动物模型中，使用生长因子局部递送和手术肌腱修复，在较短的时间内增加肌腱强度。特别地，生长和分化因子5和7（GDF 5和GDF 7）是适当的肌腱形成所需的，并且已经显示当应用于受损的肌腱组织时显著改善愈合。在这里，我们提出了一种基于肽的涂层的制造，允许这些生长因子的加载到肌腱组织的手术修复过程中使用的缝合线，以促进其持续释放。利用噬菌体展示技术，Affinergy筛选了表达数十亿肽序列的文库，寻找那些结合生物治疗剂和合成材料的肽。从先前鉴定的肽中，鉴定出几种与缝合材料结合的肽，然而，GDF 7/5结合肽不能从已经合成的肽中立即获得。因此，用固定化的GDF 7作为靶标进行新一轮噬菌体展示生物淘选。对于这一轮的噬菌体展示，使用了一个集中的噬菌体文库，最初设计用于寻找对BMP-2特异的肽，BMP-2是另一个TGF-β超家族成员。该文库揭示了几种能够以亚M亲和力结合GDF 7的肽序列。在鉴定这些序列后，使用缀合策略，通过生物素：链霉亲和素系统连接缝线结合肽和GDF 7结合肽，以测试其作为双功能接头分子的潜在功效。这些缀合物能够将生物活性GDF 7保留在缝合线表面，以及维持其释放到周围细胞。最后，将这些肽合成为一个连续的线性肽，以产生双功能肽，其与链霉亲和素缀合物接头相比没有表现出相似的亲和力。因此，提出了新的IFBM制剂，其复制了链霉亲和素缀合分子的肽组成和取向。使用新的连接化学和方向的IFBM的早期优化已经产生了双功能肽，其增强了GDF 7与缝合线表面的附着。因此，我们渴望启动额外的优化活动，以进一步增强这些肽。这些数据提供了初步的概念验证证据，表明生物活性GDF 7可以通过一种新的GDF 7：缝线结合肽在缝线表面递送。探索体内功能，并启动产品开发，现在是必不可少的，以确定这种生长因子输送平台的治疗效果和商业可行性。 公共卫生相关性：随着历史上最活跃的老年人迅速出现，对治疗有问题的关节和肌腱的创新疗法的需求不断增长。在这里，我们提供了成功完成I期研究项目的数据，该项目开发了一种基于肽的缝线涂层，用于向手术修复的肌腱控制输送生长和分化因子（GDF）。在第一阶段开发的原型涂层将在第二阶段进一步优化，使用Affinergy设计的新肽缀合和连接化学。我们还将进一步验证我们的肽涂层，为手术肌腱修复的体内动物模型做准备。这些动物研究将为我们的肽在手术修复后在缝合线上局部递送GDF的功效和可行性提供第一个证据。

DESCRIPTION (provided by applicant): Of the nearly 5 million patients who visit a physician for tendon pain each year in the US, approximately 200,000 go on to have a surgical repair. And while surgical repair has a high-rate of symptom relief, recovering patients are routinely immobilized for several months. Increased tendon strength, during shorter time courses has been reported in animal models using the localized delivery of growth factors with surgical tendon repair. In particular, the growth and differentiation factors 5 and 7 (GDF5 and GDF7) are required for proper tendon formation, and have been shown to dramatically improve healing when applied to damaged tendon tissue. Here we propose the manufacture of a peptide-based coating, permitting the loading of these growth factors to the sutures used during surgical repair of tendon tissue to promote their sustained release. Using phage display technology, Affinergy has screened libraries expressing billions of peptide sequences, searching for those peptides which bind biologic therapeutics and synthetic materials. From previously identified peptides, several were identified which bind to suture materials, however GDF7/5 binding peptides were not immediately available from those already synthesized. Therefore a new round of phage display biopanning was performed with immobilized GDF7 as a target. For this round of phage display, a focused phage library was used, originally designed to find peptides specific for BMP-2, another TGF-¿ superfamily member. This library revealed several peptide sequences capable of binding GDF7 with sub ¿M affinity. After identifying these sequences, a conjugation strategy, attaching suture- and GDF7-binding peptides through a biotin:streptavidin system, was used to test their potential efficacy as a bifunctional linker molecule. These conjugates were capable of retaining bioactive GDF7 to a suture surface, as well as sustaining its release to surrounding cells. Finally, these peptides were synthesized as one continuous linear peptide, to generate a bifunctional peptide, which did not exhibit similar affinity compared to the streptavidin conjugate linkers. New IFBM formulations are therefore proposed, which replicate the peptide composition and orientation of the streptavidin conjugated molecules. Early optimization of IFBMs using new linkage chemistries and orientations have resulted in bifunctional peptides which enhance GDF7 attachment to suture surfaces. We are therefore eager to initiate additional optimization activities to further enhance these peptides. These data provide initial proof-of-concept evidence that bioactive GDF7 can be delivered on the surface of sutures through a novel GDF7:suture binding peptide. Exploring the in vivo function, and initiating product development is now essential to determine the therapeutic efficacy and commercial viability of this growth factor delivery platform. PUBLIC HEALTH RELEVANCE: With the most active senior generation in history rapidly emerging, the need for innovative therapeutics to treat problematic joints and tendons continues to grow. Here we present data from the successful completion of our Phase I research program, developing a peptide-based suture coating for the controlled delivery of growth and differentiation factors (GDFs) to surgically repaired tendons. The prototype coating developed in Phase I will be further optimized in Phase II, using new peptide conjugation and ligation chemistries devised by Affinergy. We will also further validate our peptide coatings in preparation for an in vivo animal model of surgical tendon repair. These animal studies will provide the first evidence for the efficacy and feasibility of our peptides for the localized delivery of GDF on suture after surgical repair.