过表达脑源性神经营养因子的神经干细胞移植对受照海马内神经营养因子的影响

Effects of transplanting BDNF overexpressed neural stem cells on neurotrophic factor induction hippocampus after radiation exposure

目的探讨过表达脑源性神经营养因子(BDNF)的神经干细胞(NSCs)移植入放射性脑损伤大鼠模型后,对海马内神经营养因子水平及小胶质细胞活化的影响。方法从胎鼠脑中分离海马神经干细胞并进行培养。选用绿色荧光蛋白(GFP)-慢病毒、GFP-BDNF-慢病毒感染神经干细胞。将SD大鼠按随机数表法分为4组:健康对照组、单纯照射组(R组)、照射后GFP修饰的神经干细胞移植组(R+NSCs组)、照射后GFP-BDNF修饰的神经干细胞移植组(R+BDNF-NSCs组)。全脑单次20 Gy照射后1个月将神经干细胞移植入大鼠双侧海马内。移植后2和8周检测海马组织中BDNF、胶质源性神经营养因子(GDNF)、神经生长因子(NGF)的表达情况;免疫荧光染色观察小胶质细胞活化情况。结果移植后2和8周时,与R组相比,R+BDNF-NSCs组海马组织中BDNF、NGF蛋白表达均水平明显增高(P<0.05);移植后8周R+NSCs组和R+BDNF-NSCs组活化的小胶质细胞与R组相比并未显著减少(P>0.05)。结论过表达BDNF的神经干细胞移植后促进BDNF、NGF的产生,增加了辐射暴露后的海马内神经营养因子水平。

Objective To evaluate the effects of neural stem cells (NSCs) overexpressing brain-derived neurotrophic factor (BDNF) on the levels of neurotrophic factors and microglia activation in hippocampus after brain irradiation. Methods Hippocampal NSCs were isolated from fetal rat brain and infected with GFP-lentivirus and GFP-BDNF-lentivirus. SD rats were randomized into four groups: control group, irradiated group (R group), GFP-modified NSCs transplantation group with irradiation (R+ NSCs group), and GFP-BDNF modified NSCs transplantation group with irradiation (R+ BDNF-NSCs group). NSCs were transplanted into the bilateral hippocampus of rats one month after whole brain irradiation at a single dose of 20 Gy. The expressions of BDNF, glial-derived neurotrophic factor (GDNF) and nerve growth factor (NGF) in hippocampus were detected at 2 and 8 weeks after transplantation. The activation of microglia was observed by immunofluorescence. Results At 2 and 8 weeks after transplantation, the expressions of BDNF and NGF proteins in hippocampus of R+ BDNF-NSCs group were significantly higher than those of R group (P<0.05). The activated microglia in the R+ NSCs group and the R+ BDNF-NSCs group had no decrease compared with R group (P>0.05). Conclusions The transplantation of NSCs overexpressing BDNF promotes the production of BDNF and NGF, which improves the level of neurotrophic factors in hippocampus after radiation.