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目的研究5_氮杂胞苷诱导骨髓源性心肌干细胞(MCSC)向心肌分化过程中,心肌肌钙蛋白T(cTnT)的表达变化和超微结构。方法从SD大鼠骨髓间充质干细胞(MMSC)中筛选MCSC,用5_氮杂胞苷诱导向心肌定向分化。取分化后不同时间的细胞作cTnT免疫细胞化学染色,并对结果进行图像分析。透射电镜下观察分化细胞的超微结构。取不同发育期和成熟期的SD大鼠心肌作对比研究。结果用5_氮杂胞苷诱导后2周,细胞内开始表达cTnT;诱导后3周,cTnT表达增强,可见横纹样结构;诱导后4周,cTnT表达明显增强,横纹增多,但排列不规则。诱导后4周的细胞内出现心房粒,可见丰富的粗面内质网和糖原。胚胎11d大鼠的心肌内,横纹样结构较少且排列不规则。新生大鼠心肌内横纹增多,排列较规则。1月龄和3月龄心肌的横纹样结构发达,排列规则。诱导分化后4周的细胞cTnT表达特征与胚胎11d的心肌相似。结论MCSC经5_氮杂胞苷诱导后可分化为心肌细胞,表现为未成熟心肌的结构和功能特征。
Objective To investigate the expression and ultrastructure of cardiac troponin T (cTnT) in the process of 5-azacytidine-induced cardiomyocyte stem cell (MCSC) differentiation. Methods MCSCs were screened from SD rat bone marrow mesenchymal stem cells (MMSCs) and induced into cardiac myocytes by 5_ azacytidine. The cTnT immunocytochemical staining was performed on the cells at different time points after differentiation, and the images were analyzed. The ultrastructure of differentiated cells was observed under transmission electron microscope. Take different developmental and maturation of SD rat heart for comparative study. Results cTnT began to be expressed in the cells 2 weeks after induction with 5-azacytidine; cTnT expression was enhanced 3 weeks after induction, indicating that the striated pattern was observed. At 4 weeks after induction, the expression of cTnT was significantly increased, rule. 4 weeks after induction of intracellular atrial grains, showing a rich rough endoplasmic reticulum and glycogen. In the 11d rat myocardium, there were few horizontal stripes and irregular arrangement in the myocardium. Newborn rat myocardial increased stripes arranged more regularly. 1 month old and 3-month-old horizontal structure of the heart-shaped hair, arranged in the rules. The characteristics of cTnT expression in cells at 4 weeks after differentiation were similar to those on embryonic day 11. Conclusion MCSCs can differentiate into cardiomyocytes induced by 5-azacytidine, showing the structural and functional characteristics of immature myocardium.