Oligodendrocyte Genesis after Spinal Cord Injury

描述（由申请人提供）：脊髓损伤（SCI）后发生迟发性少突胶质细胞（OL）死亡。由于这些细胞对轴突形成髓鞘，它们的缺失导致轴突功能障碍，并导致脊髓损伤后功能丧失。尽管许多研究描述了脊髓损伤后的OL死亡，但很少有人研究内源性OL替代是否发生。我们最近注意到脊髓损伤后病变腔周围组织边缘产生大量新的ol。在目前的提案中，这些令人兴奋的发现将通过确定这些新的ol是否有助于轴突再髓鞘形成并检查其形成的机制来跟进。具体来说，我们将验证创伤性损伤的成人脊髓中OL的发生导致脊髓轴突的再髓鞘形成，并依赖于星形胶质细胞衍生的CNTF的假设。在Aim 1中，我们将通过描述脊髓损伤后脊髓鞘再鞘化的时空范围来扩展初步数据。由于只有新生成的OLs才能使轴突再髓鞘化，因此该数据将提供有关新细胞有助于内源性修复的程度的信息。为了补充这些数据，我们将使用gfp逆转录病毒谱系追踪来检查损伤后分裂细胞的命运，并荧光标记新衍生的OLs和髓鞘轴突。这些研究将在Aim 2中继续进行，检查脊髓损伤后新的OL发生和OL再髓鞘形成在多大程度上取决于CNTF的存在。慢病毒- sirna技术将用于沉默CNTF的表达，并检查脊髓中少突胶质细胞祖细胞增殖、新OL形成和髓鞘形成的变化。根据我们的试验数据，我们预测沿病变边界的OLs数量将显著减少，从而导致脊髓轴突髓鞘再生减少。我们还将研究CNTF缺失和寡聚发生减少的功能后果。在Aim 3中，我们将研究CNTF介导效应的作用机制，包括评估CNTF受体和细胞内信号分子的细胞表达。由于已知CNTF可以刺激FGF-2的产生，并且我们和其他人发现FGF-2在SCI后上调，我们还将评估CNTF是否对SCI后FGF-2表达至关重要。总的来说，所产生的数据将为受伤的成人中枢神经系统中新OL形成的调控以及这些细胞帮助修复创伤性脊髓损伤的能力提供新的信息。这一建议的意义在于，这些数据将阐明脊髓损伤后新细胞是如何形成的，以及新细胞是否有助于修复损伤。通过了解控制新细胞形成的因素，我们将了解细胞能够做什么以及如何操纵损伤部位以增强其修复能力。

DESCRIPTION (provided by applicant): Protracted oligodendrocyte (OL) death occurs after spinal cord injury (SCI). Because these cells myelinate axons, their loss leads to axon dysfunction and contributes to functional loss after SCI. Although many studies have characterized OL death after SCI, few have examined whether endogenous OL replacement occurs. We recently noted that a large number of new OLs are generated in the rim of tissue surrounding the lesion cavity after SCI. In the current proposal, these exciting findings will be followed up by determining if these new OLs contribute to axon remyelination and examining the mechanisms involved in their formation. Specifically, we will test the hypothesis that OL genesis in the traumatically injured adult spinal cord leads to remyelination of spinal axons and is dependent on astrocyte-derived CNTF. In Aim 1, we will expand upon preliminary data by characterizing the spatio-temporal extent of OL remyelination after SCI. Because only newly generated OLs can remyelinate axons, this data will provide information on the extent that the new cells contribute to endogenous repair. To complement this data, we will use GFP-retroviral lineage tracing to examine the fate of dividing cells after injury and to fluorescently label newly derived OLs and myelin ensheathing axons. These studies will be followed up in Aim 2 by examining the extent to which new OL genesis and OL remyelination depend on the presence of CNTF after SCI. Lentiviral-siRNA technology will be used to silence CNTF expression and spinal cords will be examined for changes in oligodendrocyte progenitor proliferation, new OL formation and myelination. Based on our pilot data, we predict that the number of OLs along lesion borders will be significantly reduced thereby leading to a decrease in remyelination of spinal axons. We will also examine the functional consequences of the absence of CNTF and reduction on oligogenesis. In Aim 3, we will examine the mechanisms of action for CNTF-mediated effects, including evaluating cellular expression of CNTF receptors and intracellular signaling molecules. Since CNTF is known to stimulate FGF-2 production and we and others show that FGF-2 is upregulated after SCI, we will also evaluate whether CNTF is essential for post-SCI FGF-2 expression. Collectively, the data generated will provide novel information on regulation of new OL formation in the injured adult CNS and the ability of these cells to help repair the damage induced by traumatic SCI. PUBLIC HEALTH RELEVANCE The relevance of this proposal is that the data will shed light on how new cells are formed after injury to the spinal cord and whether the new cells can help repair the damage. By understanding what controls the new cell formation, we will gain an understanding of what the cells are capable of doing and how to manipulate the injury site to enhance their reparative abilities.