骨髓干细胞动员与缺血心肌血管再生

Mobilization of bone marrow stem cells and ischemia myocardial neovascularization

目的:探讨动员急性心肌梗死大鼠骨髓干细胞归巢于梗死心肌后实现血管再生的能力。方法:实验选用10～12周龄的雄性Wistar(清洁级)大鼠60只,随机分为3组:急性心肌梗死+动员组、急性心肌梗死组及对照组,每组20只。结扎Wistar大鼠左冠状动脉制作心肌梗死模型,用骨髓干细胞动员剂粒细胞集落刺激因子动员自体骨髓干细胞释放并归巢于心肌梗死灶,于造模后24,48h和4周杀死大鼠,取出心脏,通过免疫组化方法观察心肌梗死灶、边缘区和正常心肌组织CD34阳性细胞、血管内皮生长因子及其受体的表达,以及VIII因子表达,并应用流式细胞术比较动员前后外周血中CD34阳性细胞数量的变化。结果:急性心肌梗死+动员组大鼠造模24h,4周后外周血CD34细胞数量分别为(0.919±0.187)%,(0.834±0.110)%,明显高于造模前犤(0.043±0.023)%犦及心肌梗死组大鼠造模24h,4周后犤(0.071±0.104)%,(0.062±0.296)%犦(t=2.697,2.354,2.492,2.195,P<0.05)。急性心肌梗死+动员组大鼠心肌梗死区可见CD34阳性细胞浸润;制模后4周,急性心肌梗死+动员组微血管新生数明显多于急性心肌梗死组和对照组(t=3.125,3.308,P<0.01)。急性心肌梗死+动员组大鼠梗死灶及周围组织中血管内皮生长因子及其受体的表达量均明显高于急性心肌梗死组及假手术组(t=2.099～3.398,P<0.05)。结论:骨髓干细胞动员的方法在大鼠急性心肌梗死模型中,能通过动员内皮干细胞归巢于梗死灶内,有效促进微血管形成;还通过上调血管内皮生长因子及其受体的表达,促进血管再生,促进缺血心脏功能恢复。

AIM:To investigate the ability of granulocyte colony stimulating factor-mobilized bone marrow stem cells to induce angiogenesis in rats with acute myocardial infarction, and study its mechanism.METHODS: Sixty 10 to 12 week old male Wistar rats (clean degree) were randomly divided into acute myocardial infarction+ mobilization group(n =20),acute myocardial infarction group (n=20) and control group (n=20). Left anterior descending coronary arteries were ligated to produce acute myocardial infarction models. Bone marrow stem cells were mobilized by granulocyte colony stimulating factor and homed to the site of myocardial infarction.The rats were killed at 24 and 48 hours and 4 weeks after acute myocardial infarction modeling, and the hearts were harvested. Immunohistochemisty was used to observe the CD34 positive cells, expressions of vascular endothelial growth factor and its receptors , and expression of Ⅷ factor in the infarcted myocardium, margin area and normal myocardial tissues, and the changes of the CD34 positive cell number in peripheral blood before and after mobilization was determined with flowcytometry.RESULTS: The numbers of CD34 cells at 24 hours and 4 weeks after acute myocardial infarction modeling in the acute myocardial infarction+ mobilization group [(0.919± 0.187)% , (0.834± 0.110)% ] were obviously higher than that before acute myocardial infarction modeling [(0.043 ± 0.023)% ] and those at 24 hours and 4 weeks after acute myocardial infarction modeling in the acute myocardial infarction group [(0.071 ± 0.104)% ,(0.062± 0.296)% ] (t=2.697, 2.354, 2.492, 2.195, P< 0.05).In the acute myocardial infarction+ mobilization group, the infiltration of CD34 positive cells could be observed in the infarcted myocardium of the rats. Four weeks after acute myocardial infarction modeling, the number of neovascularization in the acute myocardial infarction+ mobilization group was significantly more than those in the acute myocardial infarction group and control group(t=3.125, 3.308, P< 0.01).The expression of vascular endothelial growth factor and its receptor in the infarcted myocardium and the surrounding areas of rats were remarkably higher in the acute myocardial infarction+ mobilization group than in the acute myocardial infarction group and sham operated group (t=2.099 to 3.398, P< 0.05). CONCLUSION: In the acute myocardial infarction model of rat, mobilization of bone mobilized bone marrow stem cells can increase the capillary density by mobilize endothelial stem or progenitor cells, and improve the acute ischemic cardiac function by upregulating the expressions of vascular endothelial growth factor and its receptor, enhance angiogenesis and promote the functional recovery of ischemic heart.