慢病毒载体介导Bdnf基因修饰的骨髓间质干细胞移植治疗脑梗死

Therapeutic Efficacy of Lentiviral Vector Mediated Bdnf Gene-modified MSCs in Cerebral Infarction

摘要:

为研究经Bdnf基因修饰的骨髓间质干细胞(Mesenchymal stem cells, MSCs)对脑梗死的协同治疗作用, 构建带有大鼠Bdnf基因之慢病毒载体, 并感染大鼠骨髓间质干细胞(Rat mesenchymal stem cells, rMSCs)。运用线栓法制备大鼠大脑中动脉栓塞模型, 经尾静脉注射移植, 对照组注射0.1 mol/L磷酸盐缓冲液(PBS)1 mL, Bdnf-rMSCs和Mock-rMSCs组分别注射Bdnf-rMSCs细胞悬液以及未插入目的基因的空病毒载体感染后的rMSCs细胞悬液各1 mL。各组大鼠分别于术后24 h、移植后2周及2月应用modified Neurological Severity Scores (mNSS)评价神经功能状况。结果显示, 与对照组相比, Mock-rMSCs及Bdnf-rMSCs移植组神经功能改善明显, mNSS评分差异有统计学意义(P<0.001), 而且Bdnf-rMSCs移植组明显优于Mock-rMSCs移植组(P<0.001)。移植后2周及2月, 与对照组相比两移植组梗死区脑组织结构恢复较好, 均可见EGFP阳性细胞在梗死区及其周边区聚集并存活, 并有部分细胞出现神经元样改变。Bdnf- rMSCs移植组中移植细胞大量表达BDNF, 两移植组中均有部分植入细胞表达神经细胞表面标志物。研究表明Bdnf基因修饰的rMSCs经静脉移植后可迁移至脑梗死灶周围, 向神经细胞分化并长期存活。移植后的干细胞可与其分泌的BDNF协同促进脑梗死后神经功能恢复, 这为将来基因工程干细胞移植治疗脑梗死提供了实验依据。

Abstract:

Pretreatment with brain-derived neurotrophic factor(BDNF) reduces ischemic damage after focal cerebral ischemia, and bone marrow mesenchymal stem cells(MSCs) were reported to ameliorate functional deficits after stroke in rats. Here we investigate the synergistically therapeutic effects of BDNF gene-modified MSCs on cerebral infarction. We transfected MSCs with the BDNF gene using a lentivirus-based system and investigated whether the BDNF-modified MSCs contributed to improved functional recovery in a rat transient middle cerebral artery occlusion(MCAO) model. Compared to untreated rats, rats that received both MSCs and BDNF-MSCs showed significantly more functional recovery. The difference in modified neurological severity score(mNSS) was statistically significant(P<0.001). Recovery was better in BDNF-MSCs than in MSCs(P<0.001). At the second week and second month after the systemic delivery of blank vector-modified MSCs and BDNF-modified MSCs, the treated rats exhibited more significant recovery than the control, including the accumulation and living of enhanced green fluorescence protein(EGFP)-positive cells in the infarct area and surrounding areas, neuron-like changes, expression of surface markers of neural cells, and a large amount of BDNF expression in the BDNF-MSCs-treated group. Our findings suggest that BDNF-gene-modified rMSCs can migrate to surrounding areas of the cerebral infarction lesion, differentiate into neural cells, and survive for extended periods. With the synergy of BDNF, they may promote the recovery of the neurological function following cerebral infarction and represent a new strategy for stem cell-based therapy.