Immobilizing Gradients of Neurotrophic Factors On An Aligned Biomaterial Scaffold

将神经营养因子的梯度固定在对齐的生物材料支架上

• 批准号: 8398526
• 负责人: Nicholas Stephanopoulos
• 金额: $ 4.92万
• 依托单位: NORTHWESTERN UNIVERSITY AT CHICAGO
• 依托单位国家: 美国
• 财政年份: 2012
• 资助国家: 美国
• 起止时间: 2012-06-01 至 2015-05-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8398526
• 关键词: Acute; Adhesives; Afferent Neurons; American; Apoptosis; Axon; Binding; Biocompatible; Biocompatible Materials; Brain-Derived Neurotrophic Factor; Cell Adhesion; Cells; Charge; Chemistry; Chronic; Cicatrix; Diffusion; Drug Formulations; Effectiveness; Encapsulated; Environment; Epitopes; Equipment; Fiber; Gel; Generations; Goals; Growth; Growth Factor; Hydrogels; In Situ; In Vitro; Injectable; Injury; Length; Lesion; Life; Liquid substance; Measures; Medical; Methods; Modeling; Modification; Motor Neurons; Muramidase; Natural regeneration; Nature; Neurites; Neurons; Peptides; Property; Proteins; Recovery of Function; Regenerative Medicine; Reporting; Sensory; Signal Transduction; Site; Solutions; Spinal Cord; Spinal Ganglia; Spinal cord injury; Structure; Surface; System; Work; axon growth; axon guidance; axon regeneration; base; chemical property; improved; instrumentation; motor control; nanofiber; neurotrophic factor; novel; physical property; research study; restoration; scaffold

DESCRIPTION (provided by applicant): Biomaterials for promoting neuron regeneration and directing axon growth following spinal cord injury (SCI) represent a highly promising field for treatment of this devastating condition. In particular, a material that mimics the highly aligned nature of the spinal cord will be particularly effective at directing axon regeneration through the site of injury. A number of studies have shown the effectiveness of gradients of growth factors NGF (for sensory neurons) and NT-3 or BDNF (for motor neurons), at both stimulating and directing axon regrowth following SCI. The proposed work outlines a strategy for functionalizing a highly aligned biomaterial hydrogel with gradients of these growth factors in order to direct and promote axon regeneration. The biomaterial will be composed of peptide amphiphile (PA) molecules that self-assemble into nanofibers and can be used to form a biodegradable hydrogel with the fibers aligned over macroscopic distances. Preliminary work by the applicant has demonstrated that aligned PAgels can efficiently entrap a number of proteins for several weeks, regardless of size and charge, including lysozyme (which has the same size and charge as most neurotrophins). In addition, a stable gradient of protein can be constructed along the aligned axis by using a simple diffusion-based method that allows for direct generation of the gradient immediately prior to biomaterial gelation. Building on this work, the ability of the gel t retain and create a stable gradient of growth factors will be investigated. The gel's ability to immobilize well-defined gradients of neurotrophins, in concentration ranges previously shown to promote bioactivity, will be investigated in detail. Following construction of the gel, neurons wil be incorporated into the material in order to determine its effectiveness at promoting and directing axon growth. Both dorsal root ganglia neurons (which respond to NGF), and corticospinal motor neurons (which respond to NT-3) will be incorporated into PA gels bearing the appropriate neurotrophin gradients. The length and number of axons, as well as their directionality and rate of growth will be determined, and the gradient parameters will be tuned to optimize these measures of axon growth. If successful, the work proposed will create the first biocompatible, degradable, and easily injectable biomaterial that possesses a long-lived gradient of growth factors on a highly aligned and cell-adhesive scaffold. In the long term, this material could be injected and gelled in the injury site following either acute or chronic SCI in order to stimulate axon growth and functional connectivity, reversing or at least mitigating the effects of the injury. PUBLIC HEALTH RELEVANCE: The proposed project, which seeks to synthesize a highly aligned and injectable scaffold bearing long-lived gradients of neuroactive growth factors, will create a novel biomaterial for neuron regeneration in spinal cord injury. The gradients of growth factors immobilized on the material will help stimulate axon growth, as well as direct it in the proper direction. The long term application of this material will be as a highly translatable medical treatment to help promote axon regeneration in order to reestablish functional connectivity following spinal cord injury (acute or chronic), restoring both sensory and motor control and mitigating the deleterious effects of the injury.

描述（由申请人提供）：用于促进神经元再生和指导脊髓损伤后轴突生长（SCI）的生物材料代表了治疗这种毁灭性状况的高度有希望的领域。特别是，一种模拟脊髓高度排列性质的材料将特别有效地指导轴突再生 受伤部位。许多研究表明，在SCI之后，在刺激和指导轴突再生时，生长因子NGF（用于运动神经元）和NT-3或BDNF（对于运动神经元）的有效性。拟议的工作概述了一种用这些生长因子的梯度来使高度对准的生物材料水凝胶功能功能化的策略，以指导和 促进轴突再生。生物材料将由自组装成纳米纤维的肽两亲物（PA）分子组成，可用于形成可生物降解的水凝胶与在宏观距离上排列的纤维的可生物降解水凝胶。申请人的初步工作表明，对齐的Pagels可以有效地捕集许多蛋白质的蛋白质数周，而不论大小和电荷，包括溶菌酶（溶菌酶的大小和电荷与大多数神经营养蛋白具有相同的大小和电荷）。此外，可以使用简单的基于扩散的方法沿对齐轴构建稳定的蛋白质梯度，该方法可以在生物材料凝胶化之前立即直接生成该梯度。在这项工作的基础上，将研究凝胶T保留并创建稳定的增长因素的能力。凝胶固定固定明确的神经营养剂梯度的能力，以先前显示的促进生物活性的浓度范围，将详细研究。凝胶构造后，神经元将被纳入材料中，以确定其在促进和指导轴突生长方面的有效性。双背神经元神经元（对NGF反应），皮质脊髓运动神经元（对NT-3反应）将掺入具有适当的神经营养剂梯度的PA凝胶中。将确定轴突的长度和数量及其方向性和生长速率，并将调整梯度参数以优化轴突生长的这些度量。如果成功的话，提出的工作将创建第一个生物相容性，可降解且易于注射的生物材料，该生物材料具有长期寿命的生长因子梯度，以高度排列和细胞粘附的脚手架。从长远来看，急性或慢性SCI后可以将该材料注入并在损伤部位注入并凝胶，以刺激轴突的生长和功能连通性，逆转或至少减轻损伤的影响。 公共卫生相关性：拟议的项目旨在综合具有长期的神经活性生长因子寿命长梯度的高度对齐和可注射的脚手架，将为脊髓损伤中的神经元再生带来新的生物材料。固定在材料上的生长因子的梯度将有助于刺激轴突的生长，并将其指向正确的方向。该材料的长期应用将是一种高度可翻译的医学治疗，以帮助促进轴突再生，以便在脊髓损伤（急性或慢性）后重建功能连通性，恢复感觉和运动控制并减轻损伤的有害影响。