移植BDNF和GDNF基因修饰的hMSCs对大鼠大脑中动脉阻塞的影响

Effect of transplantation of hMSCs modified by BDNF and GDNF gene on injured brain in rat MCAO model

目的:构建脑源性神经营养因子(BDNF)和胶质细胞源性神经营养因子(GDNF)基因的非病毒表达载体,用脂质体法转染人骨髓间充质干细胞(hMSCs),观察其对大鼠大脑中动脉阻塞(MCAO)模型的影响,探索移植转基因修饰的hMSCs治疗脑血管疾病的可行性。方法:构建高效非病毒表达载体,用脂质体法转染获得高表达2种神经营养因子的hMSCs。建立大鼠MCAO模型,建模后24 h经股静脉进行转基因hMSCs移植,并以磷酸盐缓冲液(PBS)和hMSCs为对照。用脑梗死体积计算、体重变化、行为学评测等指标对大鼠脑损伤程度进行评估,通过大鼠脑组织观察和病理切片对脑组织损伤以及细胞的迁移分化情况进行分析。结果:经股静脉转基因hMSCs移植能够提高大鼠MCAO后的感觉运动功能,减小脑梗死体积,与PBS对照组相比有显著差异;与hMSCs治疗组相比,治疗效果较好且稳定。移植的细胞在脑损伤区域有少数存活但未见分化现象。结论:经静脉移植脂质体介导、GDNF和BDNF基因修饰的hMSCs,可促进缺血脑组织的损伤修复,效果较好,为非病毒载体在干细胞相关转基因治疗的应用提供了理论依据。本研究表明,MSCs的作用不依赖干细胞的分化和神经元的替换,而可能与其分泌细胞因子对抗脑损伤并促进神经修复有关,在MSCs中转入特定的外源性神经营养因子可加强这一作用。

AIM： To study the therapeutic effect of human mesenchymal stem cells （hMSCs） modified by brain-derived neurotrophic factor （BDNF） and glial cell line-derived neurotrophic factor （GDNF） gene transfer with lipo- some on middle cerebral artery occlusion （MCAO） model rats. METHODS： The nonviral expression vector was construc- ted and transfected into the hMSCs by hposomal method. The rat brain injury model was established by the method of MCAO. The gene-modified hMSCs, control hMSCs or PBS was transplanted into the rats 24 h after MCAO by femoral ve- nous injection. The neurological function score, the change of the body weight and the behavior test were used to evaluate the damage of the brain in the rats. The degree of the damage and the migration of the ceils 15 d after transplantation were analyzed by observing the histological changes of the brain tissues. RESULTS ： The expression levels of BDNF and GDNF in gene-modified hMSCs were much higher than those in control hMSCs. The transplantation of BDNF and GDNF gene- modified hMSCs promoted the functional recovery and reduced the infarct size in the rats after MCAO. A few exogenesis cells only survived in the infarct area of the brain in the MCAO rats, and the cells showed no differentiation. CONCLU- SION： Transplantation of BDNF and GDNF gene-modified hMSCs by nonviral expression vector is effective in treating cere- bral ischemia. The effect may result from the action of the cytokines secreted by these cells, reducing the injuries induced by the brain ischemia and acceleratin~ the nerve repair followin~ the injury.