脐血间充质干细胞静脉移植治疗新生大鼠缺氧缺血性脑损伤的时效性研究

Chronergical study on intravenous transplantation of umbilical blood mesenchymal stem cells after ischemic-hypoxic brain damage in neonatal rats

目的探讨脐血间充质干细胞(MSCs)静脉移植治疗新生鼠缺氧缺血性脑损伤(HIBD)的可行性及其时效性。方法脐血MSCs移植使用前以4′,6-二脒基-2-苯吲哚盐酸(DAPI)体外标记。实验选用7日龄SD大鼠38只制备HIBD模型,死亡3只,余35只共分3组:空白对照组(n=11);移植1组(n=12),在HIBD后第2天经鼠尾静脉注入脐血MSCs;移植2组(n=12),在HIBD后1周开始移植。两组均于移植后第2天以及HIBD后2周分别随机将鼠处死、取脑,用于脑组织病理形态学观察,并取海马回区相同部位的缺血脑组织切片,荧光显微镜下观察DAPI阳性细胞数。结果移植2组,1周后缺血脑组织细胞外间隙缩小,细胞数明显增加,脑组织水肿已明显减轻,在大鼠病灶侧脑内,可见大量的DAPI阳性细胞向病灶区及周围迁移和扩散,没有明显的界限。而移植1组于移植后病灶侧脑内很少见到DAPI阳性脐血MSCs分布,其脑组织水肿程度及细胞外间隙的改善和细胞数目的增加也不明显。结论脐血MSCs移植治疗新生大鼠HIBD,能有效透过血脑屏障,在病灶脑组织周围迁移、扩散、整合;移植时间选择HIBD后1周时有良好疗效。移植治疗过程中未见植入反应和其他不良反应。

Objective To study the feasibility and chronergy of intravenous transplantation of the human umbilical blood mesenchyrnal stem cells （MSCs） after hypoxic-ischemic brain damage （HIBD） in neonatal rats. Methods Human umbilical MSCs were cultured and labeled with 4＇, 6-Diamidino-2-phenylindole dihydrochloride hydrate （DAPI）. Among the 38 rats for HIBD model establishment, 3 rats died and the rest HIBD rats were divided into 3 groups： Control group（ n = 11 ） ; MSCs transplant group one（ n = 12, the MSCs were grafted at the second day after HIBD） and MSCs transplant group two（ n = 12, the MSCs were grafted at the second week after HIBD）. The human umbilical DAPI-labeled MSCs were grafted via the caudal vein of rats. After the rats in each group were randomly sacrificed at the second day after implantation or the second week after HIBD, brain tissue was examined pathologically and DAPI-positive cells in hippocampal gurus were counted under the fluoroscope. Results One week after transplantation, transplant group two showed less cell swelling, smaller extracellular space and more migratory cells. Moreover, DAPI-labeled MSCs were present in the damaged brain tissue of transplant group two, suggesting MSCs could cross the blood brain barrier （BBB） to migrate into the hypoxic-ischemic lesion for tissue repair. But these changes mentioned above weren＇t obvious in transplant group one. Conclusion The human umbilical blood MSCs transplantation for the HIBD treatment in the neonate rats at the second week after HIBD can effectively decrease the brain edema and relieve brain tissue damage; MSCs can cross the BBB and migrate into hypoxic-ischemic lesion. Furthermore, implantation response and adverse effects were absent in our study.