Oligodendrocyte Genesis after Spinal Cord Injury

描述（由申请人提供）：脊髓损伤（SCI）后发生前少突胶质细胞（OL）死亡。因为这些细胞使轴突髓鞘化，它们的缺失导致轴突功能障碍，并导致SCI后的功能丧失。虽然许多研究的特点是脊髓损伤后OL死亡，很少有研究是否发生内源性OL替代。我们最近注意到，SCI后在病变腔周围的组织边缘产生了大量新的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是否有助于轴突髓鞘再生并检查其形成所涉及的机制来跟进。具体来说，我们将测试的假设，即在创伤性损伤的成人脊髓OL成因导致脊髓轴突髓鞘再生，并依赖于星形胶质细胞衍生的CNTF。在目标1中，我们将通过描述SCI后OL髓鞘再生的时空范围来扩展初步数据。因为只有新生成的OL才能使轴突髓鞘再生，所以该数据将提供关于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OL和髓鞘成鞘轴突。这些研究将在目标2中通过检查SCI后新的OL发生和OL髓鞘再生依赖于CNTF存在的程度来跟踪。慢病毒-siRNA技术将用于沉默CNTF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。基于我们的初步数据，我们预测沿着沿着病变边界的OL的数量将显著减少，从而导致脊髓轴突髓鞘再生的减少。我们还将研究CNTF的缺失和减少对寡聚化的功能影响。在目标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刺激FGF-2的产生，并且我们和其他人表明SCI后FGF-2上调，我们还将评估CNTF是否对SCI后FGF-2的表达至关重要。总的来说，所产生的数据将提供新的信息，在受伤的成年中枢神经系统和这些细胞的能力，以帮助修复创伤性SCI引起的损伤的新的OL形成的调节。 这项建议的相关性在于，这些数据将揭示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。通过了解是什么控制了新细胞的形成，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.