A Rational Approach to Stimulating Peripheral Nerve Regeneration Across Criticall

描述（由申请人提供）：严重创伤性损伤和肿瘤切除等外科手术通常会造成周围神经间隙，每年在美国造成超过250，000例损伤。临床修复的“金标准”是自体移植，40~50%的患者恢复了有用的功能。自体移植物的有效性和使用受到可用性有限和供体部位附带损害等问题的限制。因此，关键是要开发替代的生物工程方法，匹配或超过自体移植的性能。我们最近报道了一个突破性的桥接临界尺寸的神经毒气（= 15毫米）在大鼠使用薄膜为基础的腔内支架进行标准的神经引导通道。这一发现引出了两个重要问题。(1)最小薄膜线索（仅占腔内体积的0.3%）的腔内呈现如何对再生产生显著影响？(2)如果我们理解了这种效应的机制，我们是否可以影响这一过程，并进一步增强再生，以匹配或超过自体移植物的性能？了解聚合物纤维为基础的地形（什么可以被称为内源性的“再生过程/序列”）之间的相互作用机制是必要的合理设计的腔内支架。这一过程自发地发生在短间隙（大鼠中<10 mm）的成功桥接期间，但在较长间隙（大鼠中= 15 mm）的桥接中未能发生。它涉及纤维蛋白缆形成、细胞外基质沉积/重塑（例如，纤维连接蛋白）、胶质/支持细胞（成纤维细胞和雪旺细胞）和轴突浸润到差距中。我们的中心假设是，具有地形线索的薄膜增强再生的机制是通过充当施旺细胞浸润、施旺细胞定向、细胞外基质沉积/组织和轴突浸润的物理“组织模板”，这反过来又导致成功的再生。我们的具体目标如下：目的1：研究在体内修复临界尺寸神经间隙过程中，聚合物纤维基薄膜形貌与纤维蛋白电缆/ECM组织和胶质细胞迁移之间的相互作用。目标二：确定影响再生顺序的可扩散生化因子的局部递送的效果，以在与地形线索结合时协同增强再生。这里的创新之处在于，我们将研究以前未充分探索的再生/伤口愈合序列的早期事件和呈现地形线索的腔内薄膜支架之间的相互作用。除了这种调节再生序列的物理模板之外，我们还提出通过持续局部递送神经营养素-3来给予其“生化增强”[目的2]。因此，我们通过合理设计极简的基于腔内膜的支架来解决重要的临床问题，该支架应a）增强我们对腔内支架设计的理解，并且B）在桥接临界尺寸的神经间隙中产生比先前从神经引导通道可获得的性能显著更好的性能。 公共卫生相关性：仅在美国，每年就有超过250，000 - 300，000例外周神经损伤。这项研究将促进我们对腔内支架促进周围神经再生机制的理解，并将开发可能改善周围神经损伤后临床结果的技术。

DESCRIPTION (provided by applicant): Severe traumatic injuries and surgical procedures like tumor resection often create peripheral nerve gaps, accounting for over 250,000 injuries in the US annually. The clinical "gold standard" for repair is autografts, with which 40~50% of patients regain useful function. The effectiveness and use of autografts is limited by issues including limited availability and collateral damage at the donor site. So, it is critical to develop alternative bioengineered approaches that match or exceed autograft performance. We recently reported a breakthrough in bridging critically sized nerve gas (=15mm) in rats using a thin film-based intra-luminal scaffold carried in a standard nerve guidance channel. This finding gives rise to two important questions. (1) How does intra-luminal presentation of minimal thin film-based cues (occupying just 0.3% of intra-luminal volume) have a dramatic effect on regeneration? (2) If we understood the mechanism underlying this effect, could we influence the process, and further enhance regeneration to match or exceed autograft performance? An understanding of the mechanistic interplay between polymer fiber-based topography (what may be termed the endogenous 'regenerative processes/sequence') is necessary for the rational design of intra-luminal scaffolds. This process spontaneously occurs during the successful bridging of short gaps (< 10mm in rats), but fails to occur in the bridging of longer gaps (=15mm in rats). It involves a fibrin cable formation, extracellular matrix deposition/remodeling (e.g., fibronectin), glial/support cell (fibroblasts and Schwann cells) and axonal infiltration into the gap. Our central hypothesis is that the mechanism by which thin films with topographical cues enhance regeneration is by serving as physical 'organizing templates' for Schwann cell infiltration, Schwann cell orientation, extra-cellular matrix deposition/organization, and axon infiltration, which in turn leads to successful regeneration. Our specific aims are as follows: Aim 1: Investigate the interplay between polymer fiber-based thin film topographyand fibrin cable/ECM organization and glial cell migration during repair of critically sized nerve gaps in vivo. Aim 2: Determine the effect of local delivery of diffusible biochemical factors that influence the regenerative sequence to synergistically enhance the regeneration when combined with topographical cues. The innovation here is that we will investigate the previously under-explored interplay between early events of the regenerative/wound healing sequence and intra-luminal thin-film scaffolds that present topographical cues. In addition to this physical template that modulates the regenerative sequence, we further propose to give it a 'biochemical boost' with the sustained local delivery of neurotrophin-3 [Aim 2]. We therefore address a significant clinical problem through the rational design of minimalist, intra-luminal film-based scaffolds that should a) enhance our understanding of intra-luminal scaffold design and b) result in significantly better performance than previously attainable from nerve guidance channels in bridging critically sized nerve gaps. PUBLIC HEALTH RELEVANCE: Over 250,000-300,000 peripheral nerve injuries occur every year in the US alone. This research will advance our understanding of the mechanisms of peripheral nerve regeneration that is promoted by intra-luminal scaffolds, and will develop technologies that are likely to improve clinical outcomes after peripheral nerve injury.