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: 9057394
• 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/9057394
• 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; FRAP1 gene; Fiber; Glypican; Goals; Growth; Guanosine Triphosphate Phosphohydrolases; Health; 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; neurotrophic factor; novel; novel strategies; novel therapeutic intervention; postsynaptic; presynaptic; reinnervation; relating to nervous system; repaired; research study; response; synaptogenesis; 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; FRAP1 gene; Fiber; Glypican; Goals; Growth; Guanosine Triphosphate Phosphohydrolases; Health; 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; neurotrophic factor; novel; novel strategies; novel therapeutic intervention; postsynaptic; presynaptic; reinnervation; 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（由申请人提供）：虽然与胚胎神经系统相比，成熟的中枢神经系统的总体再生能力降低，但当某些人群获得有效的生长耐受性环境时，例如由外周神经嫁接（PNG）提供的轴突再生。尽管如此，能够再生到移植物中的轴突仍无法超越PNG而增强脊髓，至少部分是因为存在于移植物宿主界面处的抑制性神经胶质疤痕。用软骨素酶ABC（CHABC）消化疤痕内的抑制性细胞外基质，使一些轴突可以穿越远端界面，在远端神经元上突触，并介导某些行为恢复。但是，大多数轴突仍保留在移植物中。因此，重要的是制定策略，以增强轴突从移植物中再生的能力，以提高其提高功能的潜力。我们有初步数据，表明表达组成性活性Rheb（Carheb） - GTPase是蛋白质合成的关键调节成分的GTPase-在成人神经元中，我们会导致稳健的轴突 SCI后体外神经胶质疤痕模型和体内的生长。在AIM 1中，我们将测试以下假设：SCI之后表达Carheb将增强PNG的再生和之外的再生。我们将使用组织学，生理和行为分析来检查CARHEB是否增强了轴突再生 - 尤其是在CHABC治疗远端移植物界面之后 - 以及这些再生轴突是否形成促进行为恢复的功能突触。如果这些轴突不整合到电路中，则任何再生都是无关紧要的。尽管CHABC增强了可塑性，但CHABC诱导的发芽/再生纤维并不总是形成突触以影响功能。因此，制定策略以改善这些轴突的整合（I ..突触发生）也很重要，以利用我们鼓励的再生。我们最近证明了原理证明，提供单个外源因子增强了从PNG中再生的轴突的整合。最近的工作表明，分泌的Glypican足以促进体内脑缺血模型的体外和行为恢复的功能性兴奋性突触形成。在AIM 2中，我们将测试以下假设：提供外源性Glypican将增强SCI后再生轴突的突触发生。我们将把PNG移植到已接受CHABC处理的SCI部位，以促进轴突再生。我们将确定将外源性Glypican注入SCI部位周围的组织中是否会增强这些再生轴突在PNG远端的神经元上的突触发生。我们将通过研究前和突触后标记的共定位，从生理和组织学上衡量功能突触形成的改进。我们还将评估增强的突触形成是否与行为恢复相关。由于目标1和2中要测试的策略采用不同的方法 - 分别增强生长反应和突触发生，以促进SCI后的功能修复，因此，即使先前目标中的结果是增量的，结合两种方法也会导致更大的恢复。在AIM 3中，我们将使用一种新颖的多收益策略来用增长促进病变腔填充病变腔 底物（PNG），增强生长反应（CARHEB），调节神经胶质疤痕（CHABC）的抑制特性并促进突触发生（Glypican）。我们将使用组织学和生理分析来检查Glypican是否增强了通过表达Carheb诱导的CHABC处理的PNG界面以外的轴突再生的功能整合，并且是否会导致比单独进行Carheb或Glypican治疗的情况更强大的行为恢复。这些数据将确定新的治疗策略，这些策略最终可能会转化为临床用途，以改善SCI患者的生活质量。