MULTIPRONGED APPROACH TO PROMOTE FUNCTIONAL AXONAL REGENERATION AFTER SCI

多管齐下促进 SCI 后功能性轴突再生

• 批准号: 8720393
• 负责人: Veronica Jean Tom
• 金额: $ 33.8万
• 依托单位: DREXEL UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2014
• 资助国家: 美国
• 起止时间: 2014-05-01 至 2019-04-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8720393
• 关键词: Address; Adult; Affect; American; Astrocytes; Axon; Behavioral; Cerebral Ischemia; Chondroitin ABC Lyase; Cicatrix; Clinical; Complex; Data; Distal; Embryonic Nervous System; Environment; Excitatory Synapse; Exogenous Factors; Extracellular Matrix; Fiber; Glypican; Goals; Growth; Guanosine Triphosphate Phosphohydrolases; Heparan Sulfate Proteoglycan; Histologic; In Vitro; Injury; Lead; Lesion; Mediating; Modeling; Motor; Natural regeneration; Nerve Degeneration; Nervous system structure; Neuraxis; Neurons; Pathway interactions; Peripheral Nerves; Persons; Physiological; Population; Property; Protein Biosynthesis; Public Health; Quality of life; Ras homolog enriched in brain; Recovery; Recovery of Function; Sensory; Site; Spinal Cord; Spinal cord injury; Synapses; Testing; Tissues; Translating; Work; axon growth; axon regeneration; clinical application; improved; improved functioning; in vivo Model; mTOR protein; neurotrophic factor; novel; novel strategies; novel therapeutics; postsynaptic; presynaptic; public health relevance; relating to nervous system; repaired; research study; response; synaptogenesis

DESCRIPTION (provided by applicant): While the mature central nervous system has an overall diminished capacity for regrowth compared to an embryonic nervous system, axonal regeneration of some populations is possible when they are provided with a potently growth-permissive environment, such as one conferred by a peripheral nerve graft (PNG). Still, axons that are capable of regenerating into the graft fail to grow beyond the PNG to reinnervate spinal cord, at least partly because of the presence of the inhibitory glial scar that is present at the graft-host interface. Digesting the inhibitory extracellular matrix within the scar with chondroitinase ABC (ChABC) allows some axons to traverse the distal interface, synapse upon distal neurons, and mediate some behavioral recovery. Nonetheless, most of the axons remain in the graft. Thus it is important to develop strategies that enhance the ability of axons to regenerate out of a graft in order to increase their potential to improve function. We have preliminary data indicating that expressing constitutively active Rheb (caRheb) - a GTPase that is a critical regulatory component of protein synthesis - in adult neurons results in robust axonal outgrowth in an in vitro glial scar model and in vivo after SCI. In Aim 1, we will test the hypothesis that expressing caRheb after SCI will enhance regeneration into and beyond a PNG. We will use histological, physiological, and behavioral analyses to examine if caRheb augments axonal regeneration - especially following ChABC treatment of the distal graft interface - and if these regenerated axons form functional synapses that facilitate behavioral recovery. Any regeneration is irrelevant if these axons do not integrate into circuits. Though ChABC enhances plasticity, ChABC-induced sprouted/regenerated fibers do not always form synapses to impact function. Thus, it is also important to devise strategies to improve integration of these axons (i.. synaptogenesis) in order to exploit regrowth that we encourage. We recently demonstrated the proof-of-principle that providing a single exogenous factor enhances the integration of axons that regenerate out of a PNG. Recent work indicates that secreted glypican is sufficient to promote functional, excitatory synapse formation in vitro and behavioral recovery in a cerebral ischemia model in vivo. In Aim 2, we will test the hypothesis that providing exogenous glypican will enhance synaptogenesis of regenerated axons following SCI. We will graft a PNG into a SCI site that has been treated with ChABC to promote axonal regeneration. We will determine if infusing exogenous glypican into tissue surrounding the SCI site enhances synaptogenesis of these regenerated axons upon neurons distal to the PNG. We will gauge improvements in functional synapse formation physiologically and histologically by examining the colocalization of pre- and postsynaptic markers. We will also assess if enhanced synapse formation correlates with behavioral recovery. Because the strategies to be tested in Aims 1 and 2 take different approaches - enhancing the growth response and synaptogenesis, respectively - to promote functional repair after SCI, it is possible that even if the results in the previous Aims are incremental, combining the two approaches will lead to greater recovery than either alone. In Aim 3, we will use a novel, multipronged strategy to fill the lesion cavity with a growth-promoting substrate (PNG), enhance the growth response (caRheb), modulate the inhibitory properties of the glial scar (ChABC) and promote synaptogenesis (glypican). We will use histological and physiological analyses to examine if glypican enhances the functional integration of axonal regeneration beyond a ChABC-treated PNG interface that is induced by expressing caRheb and if this results in more robust behavioral recovery than what occurs with either caRheb or glypican treatment separately. These data will identify new therapeutic strategies that may eventually be translated to clinical use to improve the quality of life of persons with SCI.

描述(申请人提供)：尽管与胚胎神经系统相比，成熟的中枢神经系统的再生能力总体上有所减弱，但当为某些人群提供一个强大的生长允许环境时，如周围神经移植物(PNG)提供的环境，轴突再生是可能的。尽管如此，能够再生到移植物中的轴突无法生长到PNG之外，无法重新支配脊髓，至少部分原因是移植物-宿主界面存在抑制性胶质瘢痕。用软骨素酶ABC(ChABC)消化瘢痕内抑制的细胞外基质，可以使一些轴突穿过远端界面，突触到远端神经元，并介导一些行为恢复。尽管如此，大部分轴突仍留在移植物中。因此，重要的是制定策略，提高轴突再生的能力，以增加他们的潜力，以改善功能。我们有初步数据表明，在成年神经元中表达结构性活性Rheb(CaRheb)-一种蛋白质合成的关键调节成分-GTPase-会导致强大的轴突 脊髓损伤后在体外胶质瘢痕模型和体内生长的研究。在目标1中，我们将检验这样一个假设，即在脊髓损伤后表达caRheb将促进PNG的再生。我们将使用组织学、生理学和行为学分析来检查caRheb是否促进轴突再生--特别是在ChABC处理远端移植物界面之后--以及这些再生的轴突是否形成促进行为恢复的功能性突触。如果这些轴突没有整合到回路中，任何再生都是无关紧要的。虽然ChABC增强了可塑性，但ChABC诱导的出芽/再生纤维并不总是形成突触来影响功能。因此，制定策略以改善这些轴突的整合也是很重要的。突触发生)，以利用我们鼓励的再生。我们最近证明了一个原理证明，提供单一的外源性因子可以增强从PNG再生出来的轴突的整合。最近的工作表明，分泌型Glypcan在体外足以促进功能性、兴奋性突触的形成，并在体内促进脑缺血模型的行为恢复。在目标2中，我们将验证这样的假设，即提供外源性Glypcan将促进脊髓损伤后再生轴突的突触发生。我们将PNG移植到用CHABC治疗的脊髓损伤部位，以促进轴突再生。我们将确定将外源性Glypcan注入脊髓损伤部位周围组织是否增强了这些再生轴突在PNG远端神经元上的突触生成。我们将通过检查突触前标记和突触后标记的共存来评估功能性突触形成在生理学和组织学上的改善。我们还将评估增强的突触形成是否与行为恢复相关。因为在AIMS 1和AIMS 2中测试的策略采取了不同的方法--分别增强生长反应和突触生成--来促进脊髓损伤后的功能修复，所以即使之前的AIMS的结果是渐进的，两种方法结合起来也可能比单独使用这两种方法带来更大的恢复。在目标3中，我们将使用一种新颖的、多管齐下的策略来用促进生长的药物填充病变的空洞。 底物(PNG)，增强生长反应(CaRheb)，调节胶质瘢痕的抑制特性(ChABC)，促进突触形成(Glypcan)。我们将使用组织学和生理学分析来检验Glypcan是否增强了由表达caRheb诱导的ChABC处理的PNG界面以外的轴突再生的功能整合，以及这是否导致了比单独使用caRheb或Glypcan处理更强劲的行为恢复。这些数据将确定新的治疗策略，最终可能转化为临床使用，以改善脊髓损伤患者的生活质量。