Magnetically Templated Regeneration Scaffolds for Nerve Injury Repair

 描述（由申请人提供）：尽管在开发生物材料以指导轴突生长方面做出了重大努力，但脱细胞神经同种异体移植物和神经自体移植物仍然是修复2-12 cm横断神经间隙的周围神经损伤的唯一临床替代方案。我们认为，这是因为许多用于神经再生的生物材料不能忠实地再现天然神经细胞外基质的管状微观结构。具体而言，脱细胞神经同种异体移植物在修复~5 cm神经缺损方面的成功在很大程度上是由于保留了定向轴突生长和神经重新连接的对齐的~10 µm直径基底板管。不幸的是，神经同种异体移植物需要昂贵的处理程序，由于高成本限制了广泛的患者访问，并造成疾病传播的风险。另一方面，自体神经移植导致供体部位发病率和只有40- 50%的成功率。因此，迫切需要新的方法来工程再生支架，可以取代异体移植物和自体移植物在周围神经损伤修复。 该探索性/开发项目的目标是开发和测试一种新方法，以获得神经再生支架，该支架由天然衍生的交联水凝胶组成，具有模拟神经基底层的嵌入式管状微结构。所提出的方法，磁性模板，由分散的磁性藻酸盐微粒在预水凝胶溶液，对准的微粒成跨越间隙的柱状结构与磁场，水凝胶交联的领域，和溶解的磁性藻酸盐微粒，leavin后面对齐，连续和互连的跨越间隙的通道，使它们适合于指导轴突生长的直径。磁性模板具有以下优点：（i.）在直径和长度上模仿神经基底板管的对齐的连续管状微结构;（ii.）与天然水凝胶的相容性，导致支架具有最小的免疫原性或毒性;（iii.）与生物分子的相容性，使得未来能够并入化学和生物线索以进一步引导神经生长;（iv.）可扩展到以厘米为单位的长度;以及（v.）过程简单性和可扩展性，这将降低成本并扩大患者基础。 我们将通过两个特定的目标来实现该项目的目标，这两个目标旨在测试我们的假设：（AIM 1）管状结构的排列、直径和连通性由磁性藻酸盐微粒的总浓度、直径和磁性纳米颗粒含量以及在模板化过程中施加的磁场的大小和方向决定;和（目的2）通过磁性模板结合线性取向的通道将在体外和体内增加轴突延伸到透明质酸/胶原水凝胶中。这些研究的完成将为未来的研究阶段提供信息和动力，以开发和转化磁模板再生支架作为周围神经损伤修复中神经同种异体移植物和自体移植物的替代品。这种方法也具有广泛的适用性，用于其他组织修复应用。

 DESCRIPTION (provided by applicant): Despite significant efforts developing biomaterials to direct axon growth, decellularized nerve allografts and nerve autografts remain the only clinical alternatives for repairing peripheral nerve injuries with transected nerve gaps of 2-12 cm. It is our belief that this is because many biomaterials for nerve regeneration do not faithfully reproduce the tubular microstructure of natural nerve extracellular matrix. Specifically, success of decellularized nerve allografts in repairing nerve gaps of ~5 cm is in large part due to preservation of aligned ~10 µm diameter basal lamina tubes that direct axon growth and nerve reconnection. Unfortunately, nerve allografts require expensive processing procedures, limiting broad patient access due to high cost, and pose the risk of disease transmission. On the other hand, nerve autografts result in donor site morbidity and only 40- 50% success rates. Hence, there is a critical need for novel approaches to engineer regeneration scaffolds that may replace allografts and autografts in peripheral nerve injury repair. The goal of this exploratory/development project is to develop and test a new approach to obtain nerve regeneration scaffolds consisting of naturally derived crosslinked hydrogels with embedded tubular microstructure mimicking the nerve basal lamina. The proposed approach, magnetic templating, consists of dispersion of magnetic alginate microparticles in a pre-hydrogel solution, alignment of the microparticles into gap-spanning columnar structures with a magnetic field, hydrogel crosslinking in the field, and dissolution of the magnetic alginate microparticles, leavin behind aligned, continuous and interconnected gap-spanning channels with diameters that make them suitable for directing axon growth. Magnetic templating has the advantages of: (i.) aligned continuous tubular microstructure that mimics nerve basal lamina tubes in diameter and length; (ii.) compatibility with natural-based hydrogels, resulting in scaffolds with minimal immunogenicity or toxicity; (iii.) compatibility with biomolecules, enabling future incorporation o chemical and biological cues to further guide nerve growth; (iv.) scalability to lengths in centimeters; and (v.) process simplicity and scalability that will reduce cost and broaden patient base. We will achieve the project's goal through two specific aims designed to test our hypotheses: (AIM 1) that tubular structure alignment, diameter, and connectivity are determined by overall concentration, diameter and magnetic nanoparticle content of the magnetic alginate microparticles, and the magnitude and direction of the magnetic field applied during the templating process; and (AIM 2) that incorporation of linearly oriented channels through magnetic templating will increase axonal extension into hyaluronan/collagen hydrogels in vitro and in vivo. Completion of these studies will inform and motivate future phases of research to develop and translate magnetically templated regeneration scaffolds as alternatives for nerve allografts and autografts in peripheral nerve injury repair. This approach also has broad applicability for other tissue repair applications.