神经干细胞动脉移植治疗脊髓损伤后Bcl-2与Bax的变化

The changes of bcl-2 and bax after neural stem cell artery transplantation treating spinal cord injury

目的建立肾下腹主动脉输注神经干细胞（neural stem cell,NSC）治疗脊髓缺血损伤（spinal cord ischemia injury,SCII）大鼠模型,探讨神经干细胞移植治疗脊髓缺血损伤的机制。方法 54只成年SD雌性大鼠随机分为假手术组、对照组和NSC组,每组18只。假手术组进行手术操作,不阻断动脉;对照组大鼠行脊髓缺血再灌注损伤模型,阻断肾下腹主动脉120 min后开放;NSC组完成SCII操作后向留置针缓慢推注体外培养同源NSC100万。每组取5只动物分别于术后5 d、10 d、15 d行BBB评分和运动诱发电位检测,余下每组13只大鼠于术后7 d取材,其中8只动物用于RT-PCR和Western blot检测,5只动物用于Tunnel染色。结果术后7 d,TUNEL染色发现对照组和NSC组L2节段均存在大量凋亡细胞;术后7 d对照组和NSC组Bax和Bcl-2蛋白表达水平较假手术组明显增加（P〈0.05）,其中NSC组Bax蛋白表达水平低于对照组（P〈0.05）,Bcl-2蛋白表达水平高于对照组（P〈0.05）;NSC组Bcl-2/Bax蛋白质表达比值较对照组增加（P〈0.05）。BBB评分和MEP显示对照组和NSC组大鼠术后均存在显著功能障碍,其中NSC组大鼠BBB评分于术后10~15 d高于对照组（P〈0.05）,且MEP（10 d）的波幅增大（P〈0.05）而潜伏期缩短（P〈0.05）。结论经股动脉移植NSC,可通过上调Bcl-2表达和下调Bax表达而抑制缺血再灌注损伤脊髓细胞凋亡的发生,从而促进动物后肢运动功能的恢复。

Objective To explore the mechanism of neural stem cells （NSCs） transplantation in iscbemic reperfusion injuried spinal cord by establishing a rat model of spinal cord ischemic reperfusion injury and infusing NSCs through abdominal artery. Methods 54 adult female SD rats were randomly assigned to sham group, control group and NSC group （ 18 rats in each group）. Rats in the sham group were subjected to the operative procedure but short of blocking abdominal aorta. In the control group, vertebral artery from the abdomen aorta was cut off by the electric coagulation and the abdomen aorta was reopened after occlusion 120 rain. Rats in group NSC ,vertebral artery from the abdomen aorta was cut off by the electric coagulation and injected 1 million NSCs. The neurological functional status of animal was assessed with BBB scores and motor evoked potential at 5, I0 and 15 days post operation （5 rats in each group）. At 7 d post operation, 13 rats in each group are used for RT-PCR, Western Blot tests and TUNNEL staining. Results At 7 d after SCII, blue purple apoptosis cell could be seen in control group and NSC group. Compared with the sham group,levels of protein of Bax and Bcl-2 were increased significantly in control group and NSC group （P 〈 0.05 ）. Moreover, the protein of Bax decreased and the protein of Bcl-2 increased after NSCs transplantation, compared with those in control group （P 〈 0.05 ）. In NSC group, the BBB scales were higher than that in control group （P 〈0.05） at 10 d and 15 d after SCII ,and MEP amplitude and latency were significantly improved （P 〈 0.05）. Conclusion NSC transplantated in injuried cord can suppress apoptosis by upregulating the expression of Bcl-2 and downregulating the expression of Bax. Therefore, NSCs transplantation promotes the recovery of hindlimbs locomotors function in rats.