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目的观察大鼠急性心肌梗死后心肌干细胞在梗死病程中的动态变化。方法成年SD大鼠50只,结扎冠状动脉前降支制备急性心肌梗死模型,在术前及术后1周、2周、3周和4周分别检测心功能指标:左室射血分数(LVEF)、左室短轴缩短率(LVFS)、左室舒张末期内径(LVEDD)、左室舒张末期容积(LVEDV)和左室后壁舒张末期厚度(LVPWT)。取各组大鼠新鲜心脏,石蜡切片、Masson染色,确定心肌梗死的病理变化。利用免疫组织化学技术对各组心脏切片进行免疫染色,观察干细胞抗原-1(Sca-1)、Nanog阳性心肌干细胞的动态变化。对每组切片阳性表达的细胞数进行定量分析。利用Western blotting技术观察Sca-1、Nanog的蛋白含量。结果大鼠心功能于术后1周开始降低,自第3周稳定于较低水平;Masson染色显示心肌梗死区域瘢痕组织明显,证实模型制备成功;免疫组织化学结果显示,Sca-1、Nanog阳性心肌干细胞数量在2周时上升至高峰,随后下降。结论 Sca-1、Nanog阳性心肌干细胞在心肌梗死病理演变过程中呈先上升后下降的趋势,提示心肌干细胞在心肌损伤和修复过程中发挥了重要作用。
Objective To observe the dynamic changes of myocardial stem cells in infarction course after acute myocardial infarction in rats. Methods Fifty adult Sprague-Dawley rats were randomly divided into three groups: the anterior descending branch of coronary artery was ligated to prepare acute myocardial infarction model, and the cardiac function indexes were measured before operation, 1 week, 2 weeks, 3 weeks and 4 weeks after operation. The left ventricular ejection fraction (LVEF ), Left ventricular fractional shortening (LVFS), left ventricular end-diastolic dimension (LVEDD), left ventricular end-diastolic volume (LVEDV) and left ventricular posterior wall end-diastolic thickness (LVPWT). Take fresh rat heart, paraffin sections, Masson staining to determine the pathological changes of myocardial infarction. Immunohistochemical technique was used to immunostaining cardiac sections of each group to observe the dynamic changes of stem cell antigen-1 (Sca-1) and Nanog-positive cardiac stem cells. The number of positive cells in each group was quantitatively analyzed. Western blotting was used to observe the protein content of Sca-1 and Nanog. Results The cardiac function of rats began to decrease at 1 week after operation and was stable at the lower level from the 3rd week. The Masson staining showed that the scar tissue in the myocardial infarction area was obvious. The results of immunohistochemistry showed that Sca-1 and Nanog were positive Cardiac stem cell numbers peaked at 2 weeks and then decreased. Conclusions Sca-1 and Nanog-positive cardiomyocytes initially increase and then decline in the process of myocardial infarction pathological changes, suggesting that cardiac stem cells play an important role in the process of myocardial injury and repair.