Synergistic Enhancement of Peripheral Nerve Defect Repair using Peptide Functionalized Aligned Nanofiber Conduits

周围神经再生经历了不同的阶段。在过去的几十年里，新的细节 关于周围神经再生的过程已经阐明。而轴突再生长过程 已经研究很久了，最近注意到再生和修复是与雪旺细胞同步进行的 (SC)渗入损伤的周围神经缺损区。SC招聘和定向迁移一直是一个话题 我们的实验室很感兴趣，重点是使用地形和ECM模拟进行有偏见的SC迁移 多肽。我们的体外初步数据显示，使用栓系可以明显诱导SC定向迁移 转化生长因子β多肽和YIGSR多肽的浓度梯度。我们在体内的初步数据进一步 证明合成纳米纤维支持SC的渗透和成熟。总而言之，这些数据具有 为我们提供了大量的动力来进一步研究模仿神经再生的机制 通过招聘SC的流程。为了追求这些目标，我们开发了功能性、可降解性 聚合物和多功能触摸纺丝制造策略，以生成空间定义的、生物活性的、排列的 纳米纤维导管，我们建议使用该平台来提高损伤周围的再生能力 太紧张了。我们认为，增强内源性修复过程的无细胞材料解决方案是 与翻译相关，并将为将这些功能管道翻译到临床提供最佳选择 在短期内。我们假设，在不同的浓度分布中，束缚的、基于多肽的生物活性因子， 与地形线索相结合，将增加SC的渗透，因此，神经再生 临界大小的差距。 我们将带着三个独立的目标来追求这一假说。具体目标1：系链层粘连蛋白多肽梯度 促进神经细胞迁移和SC的渗透。我们将调查系留的浓度梯度如何 层粘连蛋白多肽单独和在外植体(多细胞)模型中增强轴突和SC的反应。结果是 这一目标将产生最佳的纳米纤维(直径，层粘连蛋白-多肽梯度)，以推进我们的建议在体内 目标3.特定目标2：拴系的转化生长因子-β多肽梯度促进神经细胞迁移和干细胞 渗透。我们将研究拴系的转化生长因子-β多肽在体内的浓度梯度 联合应用RGD可单独或在外植体(多细胞)模型中增强神经突起和SC的反应。这个 这一目标的结果将产生最佳的纳米纤维(直径，转化生长因子-β肽梯度)，以推进到我们的 建议在体内进行特定目标研究3.特定目标3：体内神经再生结果随着 层粘连蛋白多肽梯度和转化生长因子-β梯度的组合。我们将使用最好的纳米纤维支架 在AIMS 1和2中独立确定，以研究层粘连蛋白多肽和转化生长因子-β的组合 多肽浓度梯度将协同增强神经再生的初始过程和长时间的 已建立的大鼠坐骨神经损伤模型的体内长期功能恢复。重点放在早期 内源性修复的步骤，以及长期恢复指标，这项工作将提供基础性证据 干细胞在神经再生过程中所起的作用。这一知识将转移我们对神经修复的关注 从轴突到已知支持再生过程的细胞，以促进恢复。

Peripheral nerve regeneration has moved through a variety of stages. Over the past few decades, new details regarding the process of peripheral nerve regeneration have been elucidated. While the axonal regrowth process has long been studied, it was noted recently that the regrowth and repair proceeds in tandem with Schwann cell (SC) infiltration into the injured peripheral nerve defect. SC recruitment and directed migration has been a topic of interest in our laboratories, with a focus on biased SC migration using topographical and ECM-mimicking peptides. Our in vitro preliminary data shows a clear induction of directional SC migration using tethered concentration gradients of both TGF-β peptide and YIGSR-peptide. Our in vivo preliminary data further demonstrates that synthetic nanofibers support SC infiltration and maturation. Together, these data have provided us with substantial motivation to further investigate mechanisms that mimic the neuroregenerative process through the recruitment of SC. To pursue these goals, we have developed functional, degradable polymers and versatile touch-spinning fabrication strategies to generate spatially-defined, bioactive, aligned nanofiber conduits and we propose to use this platform to improve the regenerative capacity of injured peripheral nerves. We believe that cell-free material solutions that enhance the endogenous repair process are translationally-relevant and will provide the best options for translation of these functional conduits to the clinic in the near term. We hypothesize that tethered, peptide-based bioactive factors in distinct concentration profiles, in combination with topographical cues, will increase SC infiltration, and therefore, neuroregeneration, across critical-sized gaps. We will pursue this hypothesis with three independent aims. Specific Aim 1: Tethered laminin peptide gradients to enhance neural cell migration and SC infiltration. We will investigate how concentration gradients of tethered laminin peptide enhance neurite and SC response, singly and in an explant (multicellular) model. The outcome of this Aim will yield an optimal nanofiber (diameter, laminin-peptide gradient) to advance to our proposed in vivo studies in Aim 3. Specific Aim 2: Tethered TGF-β peptide gradients to enhance neural cell migration and SC infiltration. We will investigate how concentration gradients of tethered TGF-β peptide-based growth factor in combination with RGD enhance neurite and SC response, singly and in an explant (multicellular) model. The outcome of this Aim will yield an optimal nanofiber (diameter, TGF-β peptide gradient) to advance to our proposed in vivo studies in Specific Aim 3. Specific Aim 3: In vivo neural regeneration outcomes improve with combinations of laminin peptide gradients and TGF-β gradients. We will use the best nanofiber scaffolds independently identified in Aims 1 and 2 to investigate whether combinations of laminin peptide and TGF-β peptide concentration gradients will synergistically enhance the initial process of neural regeneration and long- term functional recovery in vivo in a well-established rat sciatic nerve defect model. With a focus on the early steps in endogenous repair, along with a long-term recovery metric, this work will provide foundational evidence in the role that SC play in the nerve regeneration processes. This knowledge will shift our focus in nerve repair from the axon to cells that are known to support the regeneration process to enhance recovery.