脑源性神经营养因子基因修饰的骨髓间充质干细胞在药物致聋豚鼠内耳的表达及保护作用

目的 探讨脑源性神经营养因子(brain-derived neurotrophic factor,BDNF)基因修饰的骨髓间充质干细胞(mesenchymal stem cell,MSC)在药物致聋豚鼠内耳的表达及对螺旋神经节细胞(spiral ganglion cell,SGC)的保护作用.方法 阿米卡星致聋的豚鼠随机数字表法分为两组,治疗组经鼓阶开窗注射BDNF基因修饰的MSC,对照组注射外淋巴液.各组分别在术后7 d及28 d处死动物,荧光定量反转录聚合酶链反应(RT-PCR)检测耳蜗组织中BDNF mRNA的表达,耳蜗切片计算SGC细胞密度,末端脱氧核苷酸转移酶介导dUTP缺口末端标记法(terminal deoxynucleotidyl transferase mediated dUTP nick end labeling,TUNEL)检测SGC凋亡情况.结果 治疗组在术后7 d和28 d的BDNF mRNA相对表达量均明显高于对照组,差异具有统计学意义(P值均＜0.01).治疗组术后7 d及28 d的SGC密度均高于对照组,并且治疗组术后7 d及28 d的SGC凋亡指数也比对照组明显下降,差异具有统计学意义(P值均＜0.01).结论 BDNF基因修饰的MSC在致聋豚鼠内耳中的表达时间超过28 d,对SGC具有保护作用.

Expression of brain-derived neurotrophic factor modified bone marrow mesenchymal stem cells in the cochlea of drug deafened guinea pigs and its protection role

Objective To study the expression of brain-derived neurotrophic factor (BDNF)gene modified bone marrow mesenchymal stem cells (MSC) in the cochlea of drug-deafened guinea pigs and its protection to spiral ganglion cells (SGC). Methods Guinea pigs deafened by subcutaneous injection of amikacin were randomly divided into two groups, BDNF gene modified bone marrow MSC were injected into the cochlea through fenestration of scala tympani in the experimental group, while artificial perilymphatic fluid were injected in the control group. Experimental animals were executed at 7 and 28 days postoperation. Expression of BDNF mRNA was examined by quantitate real time RT-PCR, histological images of cochlear sections were analyzed to calculate the cellular density of the SGC, and terminal deoxynucleotidyl transferase mediated dUTP nick end labeling (TUNEL) was used to identify the apoptotic neurons. Results The BDNF expressive level in experimental group was higher than in the control group at 7 d and 28 d postoperation, whose differences were both statistically significant (P ＜ 0.01 ). And, It showed a higher aboundance of ganglion cell numbers, as well as a decreased apoptotic index in experimental group compared with the control group at 7 d and 28 d post-operation, whose differences were all statistically significant( P ＜0. 01 ). Conclusion BDNF gene modified MSC could maintain expression for at least 28 days after transplantation into cochlea of drug deafened guinea pigs, and protect SGC.