同种异体骨髓间充质干细胞在大鼠心脏的迁移及分化

目的探讨同种异体骨髓间充质干细胞(MSC)在大鼠心脏定居存活情况、同种异体移植是否可行。正常心脏微环境与梗死心脏微环境对骨髓间充质干细胞(MSC)迁移、分化的影响。方法雌性Wistar大鼠35只,①正常心脏MSC移植组(10只);②急性心肌梗死对照组(AMI,10只);③心肌梗死MSC移植组(10只);④单个核细胞治疗组(5只)。结扎左冠状动脉前降支造成心肌梗死模型。分离纯化来自雄性Wistar大鼠的骨髓MSC,于冠脉结扎后1～3h植入到雌性正常大鼠和心肌梗死大鼠心脏组织,模拟同种异体细胞移植治疗。于细胞移植后10周取心脏检测各种指标。结果(1)经纯化的大鼠MSC在同种异体大鼠心脏可定居、生存,而未经纯化的单个核细胞移植在同种异体大鼠心脏未见存活;(2)在正常心脏微环境中,带蓝色荧光的供体MSC细胞核呈小岛屿状分布,与宿主心肌纤维排列无关;而在心肌梗死模型大鼠心脏微环境中,蓝色细胞核分布广泛,呈椭圆形,似心肌细胞核,其排列方向与宿主心肌纤维排列方向一致,免疫组化检测胞浆心肌特异蛋白染色阳性。结论纯化的MSC具有免疫耐受特性,无需加用免疫抑制剂,可进行同种异体移植;同种异体MSC在正常心脏微环境中不发生迁移、分化;而在急性梗死大鼠心脏中具有向缺血梗死区迁移并分化为心肌样细胞的特点。

Migration and differentiation of exogenous rat mesenchymal stem cells engrafted into normal and injured hearts of rats

OBJECTIVE: To investigate the effects of different microcircumstances on the migration and differentiation of grafted rat mesenchymal stem cells (rMSC) in host myocardium and the feasibility of treatment of myocardial infarction by exogenous adult stem cells. METHODS: rMSC were isolated from the femurs and tibiae of a male Wistar rat and then purified, made into cell suspension, and labeled with DAPI. 35 female Wistar rat were divided randomly into four groups: acute myocardial infarction control group (AMI group, n = 10, the descending anterior branch of left coronary artery was ligated), acute myocardial infarction + rMSC transplantation group (AMI + rMSC group, n = 10, 1 - 3 hours after the ligation DAPI-labeled rMSC were injected into the peri-infarct tissues), normal heart + rMSC transplantation group (normal heart + MSC group, n = 10, DAPI-labeled rMSC were injected into the corresponding myocardium), and mono-nuclear cells transplantation group (AMI + MNCS, n = 5 DAPI-labeled mononuclear cells were injected into he periinfarct tissues). Ten weeks after the implantation, the rats were killed and their hearts were harvested. Immunohistochemistry was used to examine the troponin, GATA-4 and connexin-43. RESULTS: No lymphocyte proliferation and immonologic rejection were seen in the cardiac tissues of the rats implanted with rMSC. DAPI-labeled rMSC with blue nuclei were distributed extensively in the myocardium of the AMI + rMSC group, ovoid in shape and arranged in parallel with the cardiac muscle fibers, and were distributed sporadically like islands in the myocardium of the normal heart + rMSC group, irregular in shape and not arranged in parallel with the cardiac muscle fibers. No blue nucleus was seen in the cardiac tissues of the hearts implanted with DAPI-labeled mononuclear cells. Troponin and GATA4 were positive immunohistochemically in the implanted rMSC with blue nuclei and the host cardiac muscle cells of the AMI group and AMI + rMSC group, however, were negative in the implanted rMSC with blue nuclei and normal cardiac muscle cells of the normal heart + rMSC group. CONCLUSION: Purified rMSC are immunologically tolerable and can be used as donor cells for exogenous cells therapy. Capable of surviving and homing in both in normal and injured hearts, exogenous rMSC migrate and differentiate into cardiac muscle cell-like cells in myocardium with infarction, however, not in normal heart.