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

周围神经再生已经经历了不同的阶段。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。轴突再生过程 长期以来一直被研究，最近注意到再生和修复与雪旺细胞同步进行， (SC)浸润到损伤的周围神经缺损中。SC招聘和定向迁移一直是一个话题 感兴趣的在我们的实验室，重点是偏见SC迁移使用地形和ECM模拟 缩氨酸我们的体外初步数据显示，使用栓系的细胞可以明显诱导SC的定向迁移。 TGF-β肽和YIGSR-肽两者的浓度梯度。我们的体内初步数据进一步 表明合成纳米纤维支持SC浸润和成熟。总的来说，这些数据 这为我们进一步研究模拟神经再生的机制提供了巨大的动力。 为了实现这些目标，我们开发了功能性的，可降解的 聚合物和多功能的触摸旋转制造策略，以产生空间限定的，生物活性的，对齐的， 我们建议使用这个平台来提高受损外周血管的再生能力， 神经我们认为，增强内源性修复过程的无细胞材料解决方案是 与临床相关，并将为这些功能性管道的临床应用提供最佳选择 在短期内。我们假设，不同浓度分布的基于肽的生物活性因子， 结合地形学线索，将增加SC浸润，因此，神经再生， 关键的差距。 我们将以三个独立的目标来追求这个假设。具体目标1：栓系层粘连蛋白肽梯度 增强神经细胞迁移和SC浸润。我们将研究浓度梯度如何拴系 层粘连蛋白肽单独和在外植体（多细胞）模型中增强神经突和SC反应。成果 将产生最佳的直径（直径，层粘连蛋白-肽梯度），以推进我们提出的体内 目标3的研究。具体目标2：栓系TGF-β肽梯度增强神经细胞迁移和SC 浸润我们将研究栓系的TGF-β肽基生长因子的浓度梯度如何在细胞中表达。 单独和在外植体（多细胞）模型中，与RGD组合增强神经突和SC反应。的 这一目标的结果将产生一个最佳的直径（直径，TGF-β肽梯度），以推进我们的研究。 具体目标3中提出的体内研究。具体目标3：体内神经再生结果改善， 层粘连蛋白肽梯度和TGF-β梯度的组合。我们会用最好的脚手架 在目的1和2中独立鉴定，以研究层粘连蛋白肽和TGF-β的组合是否 肽浓度梯度将协同增强神经再生的初始过程和长- 在良好建立大鼠坐骨神经缺损模型中的体内长期功能恢复。专注于早期 内源性修复的步骤，沿着长期恢复指标，这项工作将提供基础证据 SC在神经再生过程中的作用。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以增强恢复的细胞。

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.