mNSCs overexpressing Rimkla transplantation facilitates cognitive recovery in a mouse model of traumatic brain injury

N-acetyl aspartyl-glutamate (NAAG) is easily inactivated by the hydrolysis of NAAG peptidase (GCPII) on the surface of glial cells, thereby losing the endogenous neuroprotection after traumatic brain injury. In recent years, the transplantation of genetically modified neural stem cells (NSCs) has made encouraging progress in reducing brain damage and promoting the recovery of brain function after traumatic brain injury (TBI). In this study, mouse embryonic neural stem cells (mNSCs) were used to over-express/knock out NAAG synthase (Rimkla) in vitro using lentiviral vectors and transplanted into the hippocampus of mice with controlled cortical impact (CCI). In vivo experiments showed that transplantation of mNSCs overexpressing Rimkla improved glutamine-glutamate cycling between astrocytes and neurons in the subacute phase of CCI, thereby enhancing neuronal metabolic support and promoting neuronal synaptic repair in the hippocampal CA3 region, and finally promoting the recovery of learning and memory in mice. Taken together, these findings confirm that overexpression of NAAG synthetases in neural stem cells can effectively maintain NAAG concentrations in local brain regions, which opens up new ideas for the maintenance of NAAG neuroprotective effects after TBI and provides a new strategy for the treatment of traumatic brain injury with neural stem cell transplantation.
RNA sequencing data were divided into mNSCs-Vector and mNSCs-Rimkla-OE groups. The hippocampal tissues of the injection side were taken for sequencing on the 7th day after injection of neural stem cells into the traumatic brain injury model mice. There were three samples in each group.

N-乙酰天冬氨酰谷氨酸（NAAG）可被胶质细胞表面的NAAG肽酶（GCPII）水解失活，进而在创伤性脑损伤后丧失其内源性神经保护作用。近年来，基因修饰神经干细胞（NSCs）移植在减轻创伤性脑损伤（TBI）后脑损伤、促进脑功能恢复领域取得了令人鼓舞的进展。本研究以小鼠胚胎神经干细胞（mNSCs）为研究对象，通过慢病毒载体在体外对其进行NAAG合酶（Rimkla）的过表达/敲除操作，随后将细胞移植至控制性皮质撞击（CCI）模型小鼠的海马区内。体内实验结果显示，移植过表达Rimkla的mNSCs可改善CCI亚急性期星形胶质细胞与神经元之间的谷氨酰胺-谷氨酸循环，从而增强神经元代谢支持、促进海马CA3区神经元突触修复，最终改善小鼠的学习记忆能力。综上，本研究证实于神经干细胞中过表达NAAG合酶可有效维持局部脑区的NAAG浓度，为创伤性脑损伤后维持NAAG的神经保护作用提供了新思路，也为神经干细胞移植治疗创伤性脑损伤提供了全新策略。
RNA测序（RNA sequencing）数据分为mNSCs-Vector组与mNSCs-Rimkla-OE组。将神经干细胞移植至创伤性脑损伤模型小鼠体内后第7天，采集注射侧的海马组织进行测序，每组设置3个样本。