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Development of an implantable multilayer three-dimensional scaffold consisting of aligned electrospun fibers for neuronal regeneration applications.

机译：开发一种可植入的多层三维支架，该支架由对齐的电纺纤维组成，用于神经元再生应用。

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摘要

There are 11,000 new spinal cord injuries (SCI) reported every year in the United States. After injury to the central nervous system (CNS), neurons do not grow through the injury site because of the presence of a glial scar that contains various inhibitory cues. Currently, there are no effective treatments to improve regenerative outcomes following CNS damage. Compared to the CNS injury, damage to the peripheral nervous system (PNS) is considerably more common. Approximately 300,000 individuals sustain injury to the PNS every year in the U.S. Nerve autografts and synthetic alternatives are currently used to repair large gaps following peripheral nerve injury. Even with these treatments, outcomes following nerve repair remain poor, resulting in full or partial paralysis. Therefore, it is imperative to develop an implantable three dimensional conduit to guide axons through the injury site.Electrospinning is a simple and versatile technique that produces ultrafine fibers made from various polymers. In this study, the optimum conditions for electrospinning aligned poly-L-lactic acid (PLLA) fibers were determined. The rotation speed of the collection disk, the size and shape of the needle tip were varied. The rate of fiber deposition (electrospinning efficiency) was improved by wrapping an insulator around the needle tip and the effect of the syringe pump flow rate was investigated. The fiber alignment and density were analyzed. It was determined that highly aligned fibers were created when the rotation speed of a collection disk was 1000 revolutions per minute (rpm), using a 22 gauge (GA) sharp needle, and a syringe pump flow rate of 2 ml/hr. The effects of fiber density on axonal outgrowth were also evaluated in vitro using embryonic stage nine chick dorsal root ganglia (E9 chick DRGs). The cell culture showed that the aligned PLLA fibers manufactured from optimized electrospinning conditions guided axonal outgrowth along the fiber. The density of axonal outgrowth was proportional to the PLLA fiber density.Based on these experimental results, an implantable multilayered three dimensional (3D) conduit was developed for neuronal regeneration applications. The conduit consisted of a double layer of PLLA films containing aligned, electrospun PLLA fibers. Fiber alignment on the film prior to conduit fabrication was characterized. Additionally, fiber morphology within the conduit was studied following conduit fabrication. Rolling the film into a three dimensional structure did not substantially affect fiber alignment. E9 chick DRGs were also cultured on a PLLA film (2D film), a PLLA film containing aligned, electrospun PLLA fibers (2D fibers), and within a conduit that contained aligned, electrospun PLLA fibers (3D fibers). Axonal outgrowth on 2D aligned fibers and within a 3D conduit was directed along the fibers, while axonal outgrowth on just the film did not grow in a directed manner. The results suggest that this multilayered 3D conduit containing aligned, electrospun fibers is a promising implantable scaffold that may organize and guide neuronal regeneration after CNS or PNS injury.
机译：在美国，每年报告有11,000例新的脊髓损伤（SCI）。损伤中枢神经系统（CNS）后，神经元不会通过损伤部位生长，因为存在包含各种抑制信号的神经胶质瘢痕。目前，尚无有效的疗法来改善中枢神经系统损伤后的再生结果。与CNS损伤相比，对周围神经系统（PNS）的损害更为普遍。在美国，每年约有300,000个人受到PNS的伤害。神经自体移植和合成替代品目前被用于修复周围神经损伤后的大间隙。即使采用这些治疗方法，神经修复后的预后仍然很差，导致全部或部分瘫痪。因此，必须开发一种可植入的三维导管来引导轴突穿过损伤部位。静电纺丝是一种简单而通用的技术，可以生产由各种聚合物制成的超细纤维。在这项研究中，确定了静电纺丝取向聚L-乳酸（PLLA）纤维的最佳条件。收集盘的旋转速度，针尖的大小和形状均发生变化。通过将绝缘体包裹在针尖周围来提高纤维沉积速率（静电纺丝效率），并研究了注射泵流速的影响。分析纤维排列和密度。当使用22号（GA）尖头针和2ml / hr的注射泵流速确定收集盘的转速为每分钟1000转（rpm）时，确定产生高度取向的纤维。纤维密度对轴突生长的影响也用胚胎期的九个鸡背根神经节（E9鸡背根神经节）进行了体外评估。细胞培养表明，由优化的电纺丝条件制成的对齐的PLLA纤维可沿纤维引导轴突生长。轴突生长的密度与PLLA纤维密度成正比。基于这些实验结果，开发了用于神经元再生应用的可植入多层三维（3D）导管。导管由双层PLLA薄膜组成，其中包含对齐的电纺PLLA纤维。在导管制造之前，对薄膜上的纤维排列进行了表征。另外，在导管制造之后研究了导管内的纤维形态。将膜卷成三维结构基本上不会影响纤维排列。 E9小鸡DRG也被培养在PLLA膜（2D膜），包含对齐的电纺PLLA纤维（2D纤维）的PLLA膜上以及在包含对齐的电纺PLLA纤维（3D纤维）的导管内。在2D对齐的纤维上和3D导管内的轴突生长沿纤维定向，而仅在膜上的轴突生长没有定向生长。结果表明，这种包含对齐的电纺纤维的多层3D导管是一种有前途的可植入支架，可在CNS或PNS损伤后组织并指导神经元再生。

著录项

  • 作者

    Wang, Han Bing.;

  • 作者单位

    Michigan Technological University.;

  • 授予单位 Michigan Technological University.;
  • 学科 Biology Neuroscience.Chemistry Polymer.
  • 学位 Ph.D.
  • 年度 2008
  • 页码 163 p.
  • 总页数 163
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类
  • 关键词

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