Factors Affecting Regeneration Through the Glial Scar

描述（由申请人提供）：我们开发了一种新的胶质瘢痕体外模型，其中粗梯度的抑制性CS-PG更接近于损伤后体内发生的模型。典型的营养不良性端球形成于成年感觉轴突的尖端，这些轴突被困在梯度内。我们现在可以第一次提出关于营养不良生长锥生物学的各种基本问题。我们希望在目标1中探讨的三个重要问题是：（A）营养不良状态是否是成年神经元的特性，（B）CNS神经元是否会对PG梯度环境做出类似的反应，以及（C）树突对抑制梯度的反应是否与轴突不同。最后，（D）我们想知道在通过新的组合再生刺激策略诱导跨过梯度的有效抑制边缘再生的可能营养不良的轴突中发生了什么分子变化。我们的最终目标是设计一个最佳的策略，在体外，可用于克服生长锥营养不良和刺激轴突再生过去的胶质瘢痕在体内。在目标2中，基于使用我们的体外梯度模型的成功再生促进策略的初步体内结果已经显示出证据，即在根挤压之前在DRG中诱导的慢性无菌炎症加上在挤压时向根进入区施加软骨素酶的组合可以促进感觉轴突稳健地再生到脊髓中。我们推测，类似的策略可能会促进感觉纤维再生在一个更临床相关的损伤后模型。我们建议研究这些纤维的功能功效。在目标3中，我们将利用一种新的扣带回微损伤模型，在该模型中，可以使最小的损伤成为可能，但仍然可以清楚地识别那些已经被切断并可能再生的轴突。在微损伤模型中，我们可以使用切割轴突的微吸管，在从大脑中取出吸管时注入桥接细胞或其他因子。初步证据表明，注射软骨素酶结合未成熟的星形胶质细胞可以刺激再生明显过去的病变。然而，一旦穿过病变，纤维只会长出很短的距离。使用这个模型，我们假设，通过也驱动其细胞体附近的再生神经元的内在生长潜力，再生将显着增强。

DESCRIPTION (provided by applicant): We have developed a new in vitro model of the glial scar in which inhibitory CS-PG in a crude gradient more closely resembles that which occurs in vivo after injury. Classic dystrophic endballs form at the tips of adult sensory axons that become trapped within the gradient. We can now ask, for the first time, a variety of basic questions concerning the biology of the dystrophic growth cone. Three important questions we wish to pursue in aim 1 are: (A) whether the dystrophic state is a peculiarity of adult neurons, (B) whether CNS neurons would respond similarly to the PG gradient environment and, (C) whether dendrites respond differently to the inhibitory gradient than do axons. Finally, (D) we would like to know what molecular changes occur in would- be dystrophic axons that are induced to regrow across the potently inhibitory rim of the gradient via a new combinatorial regeneration stimulating strategy. Our ultimate goal is to devise an optimal strategy in vitro that can be used to overcome growth cone dystrophy and stimulate axon regeneration past the glial scar in vivo. In aim 2, preliminary in vivo results based on a successful regeneration promoting strategy using our in vitro gradient model, have shown evidence that a combination of chronic sterile inflammation induced in the DRG prior to root crush, plus chondroitinase application to the root entry zone at the time of crush, can foster robust regeneration of sensory axons into the spinal cord. We hypothesize that a similar strategy may foster sensory fiber regeneration in a more clinically relevant post-injury model. We propose to study the functional efficacy of these fibers. In aim 3, we will utilize a novel microlesion model of the cingulum in which one can make the smallest lesion possible but still clearly identify only those axons that have been severed and have potentially regenerated. With the microlesion model, we can use the micropipette, that cuts the axons, to inject bridge building cells or other factors upon withdrawal of the pipette from the brain. Preliminary evidence shows that injection of chondroitinase combined with immature astroglia can stimulate regeneration clearly past the lesion. None-the-less, once past the lesion the fibers only grow short distances. Using this model we hypothesize that by also driving the intrinsic growth potential of the regenerating neurons at the vicinity of their cell body, regeneration will be significantly enhanced.