胚胎干细胞对孕鼠缺血受损心肌的修复作用

Repairing effect of embryonic stem cells on injured maternal myocardium in pregnant mice

目的探讨胎鼠胚胎干细胞是否可通过血液循环系统进入怀孕母体,并对孕鼠缺血损伤的心肌组织进行修复。方法将24只6~8周龄C57雌性小鼠随机分为假手术组（n=8）、手术＋受孕组（n=8）和手术组＋未受孕组（n=8）,通过结扎冠状动脉左前降支的方法制作心肌梗死模型,并将手术后受孕组小鼠与e-GFP转基因雄鼠进行杂交。三组小鼠分别在术前、术后和孕产后进行心电图和超声心动检测,比较其心功能的变化;通过免疫组织化学染色,观察各组小鼠心肌结构的变化,并检测孕鼠心肌是否表达荧光蛋白,以确定是否存在胚胎来源的Gfp阳性细胞。同时通过普通半定量PCR扩增技术检测孕鼠血液DNA中是否存在Gfp基因。结果手术＋受孕组及手术＋未受孕组小鼠术后心电图结果可见其ST段具有显著抬高,提示出现明显的心肌缺血表现,而手术＋受孕组小鼠产后心电图结果提示其缺血症状较孕前减轻。超声结果也证实手术后小鼠均出现明显的心肌梗死表现,手术＋受孕组小鼠产后心腔结构虽较孕前未见明显改变,各项心功能指标较假手术组减低,但与手术＋未受孕组相比,心功能指标明显升高（P〈0.05）。此外,通过免疫组化染色和PCR检测发现手术＋受孕组心肌梗死区域具有GFP阳性表达,而其他两组均为GFP阴性。结论胎鼠的胚胎干细胞可透过胎盘屏障,随血液迁移至母孕鼠体内,并对缺血损伤的心肌进行修复。

Objective To determine if fetal stem cells can enter the maternal circulation during pregnancy and repair the injuries of maternal heart. Methods C57 female mice at the age of 6- 8 weeks were randomly assigned to three groups： sham control,surgery without pregnancy,and surgery with pregnancy（ n = 8,eath group）. The control sham group was developed by opening and closing of the chest. The other two groups underwent heart surgery. The myocardial infarction（ MI） model was induced by ligation of the left anterior descending coronary artery. Half of the surgical mice mated with e-GFP transgenic male mice,and another half group was not. Electrocardiogram（ ECG） and echocardiographic images were recorded at pre-operation,post-operation and postpartum. The collected data were used to evaluate the heart function.The GFP expression was detected by immunohistochemistry and q-PCR. Results When compared with the sham group,both the ischemia surgery groups with and without pregnancy,the ECG ST segment was significantly increased. This measurement indicated that the myocardial ischemia surgery was successful,and no significant difference in the ST segments between two ischemia surgery groups was found. However,when ECG was measured in the surgical mice after postpartum,their myocardial ischemia was dramatically improved when compared with that of the ischemia surgery only mice. Echocardiographic images also indicated that both the surgery groups had myocardial ischemia,however,no significant difference was observed in the pregnant mice before and after postpartum. The order of the cardiac function indexes from high to low was the sham group,surgery with pregnancy group,and surgery with no pregnancy group; in particular,the cardiac function of pregnancy group was significantly enhanced compared with that of the surgery with no pregnancy group（ P〈0. 05）.More importantly,both immunofluorescence and q-PCR results showed that the embryonic stem cell translocation through circulation system with GFP expression in the heart of pregnancy group,while negative in other two groups. Conclusions Embryonic stem cells can be transferred into the maternal circulation of pregnant mice,and play a role in the repairing of their cardiac injuries.