Magnetically Templated Regeneration Scaffolds for Nerve Injury Repair

 描述(申请人提供)：尽管在开发引导轴突生长的生物材料方面做出了巨大努力，但脱细胞同种异体神经移植和自体神经移植仍然是修复周围神经损伤的唯一临床替代方案，周围神经损伤的横断神经间隙为2-12厘米。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复制天然神经细胞外基质的管状微结构。具体地说，脱细胞同种异体神经移植修复约5 cm的神经间隙的成功在很大程度上是由于保留了直径约10微米的排列整齐的基板管，这些管子指导轴突生长和神经重新连接。不幸的是，同种异体神经移植需要昂贵的处理程序，由于成本高，限制了患者的广泛接触，并构成了疾病传播的风险。另一方面，自体神经移植导致供区并发症，成功率仅为40-50%。因此，迫切需要新的方法来设计再生支架，以取代周围神经损伤修复中的同种异体移植物和自体移植物。这一探索性/开发性项目的目标是开发和测试一种新的方法来获得神经再生支架，该支架由天然的交联水凝胶组成，其嵌入的管状微结构模仿神经基底膜。所提出的方法，即磁性模板，包括将磁性海藻酸盐微粒分散在预水凝胶溶液中，在磁场的作用下将微粒排列成跨越间隙的柱状结构，在现场进行水凝胶交联，以及溶解磁性海藻酸盐微粒，留下排列的、连续的和相互连接的跨越间隙的通道，其直径适合指导轴突生长。磁性模板具有以下优点：(I)在直径和长度上与神经基板管相似的排列的连续管状微结构；与天然水凝胶的配伍性，导致支架的免疫原性或毒性最低；与生物分子的兼容性，使未来能够纳入化学和生物线索，以进一步指导神经生长；(Iv)可扩展到以厘米为单位的长度；以及(V)流程简单性和可扩展性，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，这些目标旨在验证我们的假设：(目标1)管状结构的排列、直径和连通性由磁性海藻酸盐微粒的总浓度、直径和磁性纳米颗粒的含量以及模板过程中施加的磁场的大小和方向决定；以及(目的2)通过磁性模板将线性取向的通道掺入透明质酸/胶原蛋白水凝胶中，将增加体外和体内的轴突延伸。这些研究的完成将为未来的研究阶段提供信息和激励，开发和转化磁性模板再生支架，作为周围神经损伤修复中同种异体神经移植和自体移植的替代品。该方法对其他组织修复应用也具有广泛的适用性。

 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.