紫杉醇调控的神经元分化在脊髓损伤修复中的谱系示踪研究

Spinal cord injury (SCI) repair is still a thorny problem of regenerative medicine. The regulation of neural stem cells (NSCs) at the injured region differentiating into neurons is one of the important challenges of reconstruction of spinal cord neural networks. Our recent studies have shown that the clinical anti-tumor drug paclitaxel, as a microtubule-stabilized drug, can promote the differentiation of NSCs into neurons in vitro when used in small doses and enhance the functional recovery of completely transected SCI animals in vivo, but its specific repair mechanism is unknown. On the basis of the above work, this project intends to use Nestin-CreERT2/pCAG-iDTR-EGFP conditional knockout mice to deeply study the role and mechanism of paclitaxel in SCI repair, verifying whether paclitaxel can improve the functional recovery of injured spinal cord by promoting endogenous neuron differentiation and further integration into the neural circuits. In addition, combined with single-cell sequencing technology, screening and functional verification of key genes of paclitaxel mediating endogenous NSCs differentiation into neurons, so as to elucidate the molecular regulatory mechanism of paclitaxel promoting endogenous NSCs differentiation into neurons after SCI.

脊髓损伤（SCI）修复目前仍是再生医学面临的一大难题。调控损伤区神经干细胞（NSCs）向神经元分化是重建脊髓神经网络的重要挑战之一。我们最近的研究表明，临床抗肿瘤药物紫杉醇作为微管稳定药物，在小剂量使用下可促进体外NSCs向神经元分化，并在体内促进全横断SCI动物功能恢复，但其具体修复机制不明。本项目拟在此基础上，利用Nestin-CreERT2/pCAG-iDTR-EGFP条件性基因敲除小鼠深入研究紫杉醇在SCI修复中的作用及机理，验证紫杉醇是否通过促进内源NSCs向神经元分化及进一步整合入神经环路提高受损脊髓功能恢复；并采用单细胞测序技术，筛选介导紫杉醇促进内源NSCs向神经元分化的关键基因并进行功能验证，从而阐明SCI后紫杉醇促进内源NSCs向神经元分化的分子调控机制。

脊髓损伤后NSCs是补充损伤部位丢失神经元的种子细胞，但无论是外源移植的NSCs还是损伤激活的内源性NSCs很少分化为神经元，而主要在损伤部位分化为星形胶质细胞，这大大影响了NSCs治疗脊髓损伤的效果。紫杉醇作为微管稳定药物不仅能促进神经轴突生长，我们前期发现它还能诱导体外NSCs定向分化为神经元，并在体内促进完全性横断脊髓损伤动物功能恢复。本课题采用转基因小鼠，可以精确追踪内源NSCs在损伤部位的分化，直接证明紫杉醇通过促进NSCs向神经元分化及进一步整合入神经环路促进完全横断脊髓损伤动物功能恢复，从而客观评价紫杉醇调控的NSCs分化在脊髓损伤修复中的作用。紫杉醇移植后在促进NSCs向神经元分化修复脊髓损伤过程中可能会触发一些相关基因表达变化，我们通过测序技术筛选并鉴定差异表达的关键基因，初步揭示了紫杉醇促进NSCs向神经元分化的分子机制。