骨髓神经组织定向干细胞移植修复噪声性聋豚鼠耳蜗毛细胞的实验研究

The experimental study on repair of noise-induced hearing loss in guinea pigs by bone marrow NTCSCs transplantation

目的:观察骨髓神经组织定向干细胞(NTCSCs)移植对噪声性聋听神经损伤豚鼠耳蜗毛细胞的修复作用。方法:将50只豚鼠按随机数字表法分为对照组(10只)、噪声暴露组(10只)和移植组(30只)。移植组及噪声暴露组豚鼠均在白噪声下暴露1周,暴露结束后将转染绿色荧光蛋白(EGFP)基因的骨髓NTCSCs移植至豚鼠左耳耳蜗蜗轴处(右耳作为自身对照,注射相同体积的0.1%PBS溶液),分别测试噪声暴露前1d和暴露后1、2及4周后的ABR阈值,并通过扫描电镜观察噪声暴露后4周豚鼠耳蜗毛细胞的形态学变化情况。结果:成功分离培养出骨髓NTCSCs,随着移植时间的延长,转染EGFP的骨髓NTCSCs球团和细胞聚集现象,逐渐接近corti器和基膜;耳蜗切片中Nestin(+)细胞的数量明显增多(P<0.05),而MyosinⅦa(+)细胞的数量无明显变化。与噪声暴露前相比,移植组豚鼠ABR阈移小于噪声暴露组(均P<0.05)。扫描电镜显示,噪声暴露组豚鼠耳蜗内、外毛细胞均出现听毛紊乱、融合及缺失;而移植组耳蜗病变较轻,听毛仅有轻微倒伏、融合现象。结论:随着骨髓NTCSCs移植时间的延长,豚鼠ABR阈值得到明显改善。骨髓NTCSCs移植后可逐渐分化成耳蜗螺旋神经节神经元,进而起到改善噪声性聋豚鼠听力的作用。

Objective：To observe the repairing effects of bone marrow transplantation with nerve tissue committed stem cell （NTCSCs） on experimental rats with injury of noise-induced hearing loss. Method：Guinea pigs were randomly divided in- to control group, noise exposure group and the transplanting group. A week after white noise exposure of 110 dB, NTCSCs and PBS were injected into guinea pigs of the noise exposure group and the transplanting group respectively. One week after noise exposure to four weeks continuous administration. ABR thresholds were measured respectively prior to the experiment, 1 week post-noise, 1,2 and 4 weeks post-drugs, The changes of cochlea hair cells were also observed by a scan electron mi- croscope （SEM）. Result：The ABR threshold shifts in the transplanting group were significantly fewer than that in the noise exposure group. SEM showed that hear hair of the inner and outer hair cells in noise exposure group displayed mess, fusion and imperfections. In the transplanting treatment group, the hair cells displayed slight pathological changes, there wasn＇t significant differents comparied with normal group. The number of OHCs were relatively stable in the normal group, while the obvious OHC loss was observed in other groups. There was significant difference among the three groups, however, the OHC loss in the transplanting group was no significantly different to that in the noise exposure （P〉0. 05）. Conclusion： The bone marrow NTCSCs which had been transplanted to rat cochlea could reduce the damage of the noise on the hair cell, and thus played a role in repairing the damage of auditory nerve.