Implantation of bone marrow mesenchymal stem cells inhibits Bcl-2 and Bax-mediated neuronal apoptosis in rats after cerebral ischemic injury / 中国组织工程研究

ABSTRACT

BACKGROUND: The implantation technique of bone marrow mesenchymal stem cells (MSCs) is of important significance for repair of brain injury. However, its action pathway still needs to be investigated.OBJECTIVE: To observe the changes of Bcl-2 and Bax expressions in the injured regions of cerebral cortex and hippocampus of rats with cerebral ischemia in which MSCs were implanted, and to analyze the action mechanism of intracranial implantation of MSCs inhibiting neuronal apoptosis.DESIGN: A randomized controlled experiment.SETTING: Institute for Cerebrovascular Disease, the Affiliated Hospital of Qingdao University Medical College.MATERIALS: Twenty-four male adult Wistar rats, weighing 180 to 240 g, were provided by the Experimental Animal Center of Shandong University. The involved rats were randomized into 3 groups with 8 in each: control group, injury group and implantation group. 5-bromodeoxyuridine (BrdU, Sigma Company), TUNEL kit, Bcl-2, Bax antibody kit were purchased from Beijing Zhongshan Bioengineering Company.METHODS: This study was carried out in the Institute for Cerebrovascular Disease, the Affiliated Hospital of Qingdao University Medical College between April 2005 and September 2006. Rats in the injury group and implantation group were developed into rat models of cerebral ischemia by suture of external carotid artery. Seven days later, the successful rat models in the implantation group were injected in the cerebral cortex and striatum with 2×1012 L-1 MSCs suspension primarily cultured in vitro. The processing of the experimental animals corresponded to the requests of Animal Ethics.MAIN OUTCOME MEASURES: Neuronal apoptosis and Bcl-2 and Bax expressions in the injured regions of cerebral cortex and hippocampus were detected by TUNEL staining and immunohistochemical method on the 7 and 14 days after successful modeling, separately.RESULTS: ①Neuronal apoptosis: On the 7th day after successful modeling, apoptotic cells were not found in the control group, and apoptotic cells in the implantation group were significantly fewer than those in the injury group (P ＜0.01). ② Bcl-2 and Bax expressions: On the 14th day after successful modeling, Bcl-2-positive neuronal expression in the cerebral cortex and hippocampus of rats in the injury group was significantly weaker than that in the control group and implantation group (P ＜ 0.01). Bax-positive expression in the cerebral cortex and hippocampus of rats in the injury group was significantly stronger than that in the control group and implantation group (P ＜ 0.01).CONCLUSION: MSCs can promote Bcl-2 expression and inhibit Bax expression of rats with cerebral ischemia injury,and accordingly neuronal apoptosis will be reduced.