新生儿窒息后缺氧缺血性脑损伤（HIBD）是导致新生儿死亡及伤残的主要原因之一。HIBD发病机制复杂，脑损伤引起的细胞丢失和炎症反应较难恢复。申请人一直从事新生儿脑损伤机制和治疗策略的研究，并提前完成了青年基金项目。前期研究发现，HI脑内神经元大量丢失伴随着星形胶质细胞（AST）活化增生形成胶质瘢痕并释放炎症因子，明显抑制了少突胶质前体细胞的分化及损伤脑的修复。我们拟通过体外培养AST并分别转染转录因子PAX6/neurog2/Dlx2/Ascl1，观察AST是否能够转分化至神经元。同时通过构建携带转录因子的腺相关病毒-9，立体注射到正常或损伤动物脑内使其特异感染AST，观察AST的原位转分化。检测不同转录因子作用下，AST的转分化效率，及转分化的神经元是否具有功能。此外，观察AST转分化对损伤脑内胶质瘢痕的形成、神经元的数目、少突胶质前体细胞的分化成熟的影响，和动物行为学是否得到提高。

Hypoxic-ischemic encephalopathy(HIE) remains one of the most important neurological disorders with high risks of severe morbidity and death in newborns, but the underlying mechanisms are complex. It is difficult for neonatals to recovery from cell loss and inflammatory reaction which caused by brain injury. At present, there is few effective treatment about HIE. The applicant has been engaged in study of mechanisms and therapeutic strategies about neonatal brain injury, and has already completed the National Natural Science Foundation named "effects of hypothermia on differentiation and maturation of oligodendrocyte precursor cells (OPC) after hypoxic ischemic brain injury" for youth. In that study, we found astrocyte acitivation and proliferation siginificantly increased in the hypoxic-ischemic injured brain, and it formed glia scar which may release a large number of inflammatory factors and suppresed neurotrophic factors secretion. This poor environment caused by astrocyte activation may lead to delayed neuron death in gray matter and impede oligodendrocyte precursor cells (OPC) differentiation and maturation in white matter of neonatal brain. This phenomenon suggested that the excessive astrocyte activation may suppressed brain repair after hypoxic ischemic injury. We prepare to transduct Lentiviral vectors containing cDNA of PAX6/neurog2/Dlx2/Ascl1 to cultured atrocytes. After that, we will detect astrocyte trans-differentiate into neuron. In vivo, we will Three-dimensionally injected lentivial vectors containg transcriptional factors and green fluorecent protein (GFP) into AST specifically in rat brain. Then, trans-differentiaiton of the transfected astrocyte will be tracked, and the numbers of newbron neurons will also be tested in the experiment. At the same time, this lentivial injection will also be injected into the area surrounding the severe injured infarct in the striatum. we will investigate if astrocyte in injured brain can transdifferentiated into neuron. The acitvation and proliferation of astrocyte, glia scar formation and neuron loss will be tested in the experiment. At the same time, the differentiation and maturation of oligodendrocyte precursor cells will also be explored in this study. We will also examined animals behavior by open filed and rotarod test in long term after brain injury in rat brain.