BACKGROUND: Intramyocardial transplantation of autologous umbilical cord-derived mesenchymal stem cells for repair of myocardial tissue damage is paid increasing attention in the cardiovascular field. OBJECTIVE: Human umbilical cord mesenchymal stem cells were isolated and cultured. Passage 2 human umbilical cord mesenchymal stem cells were treated with various concentratins of 5-azacytidine (2.5, 5, 10, 20, 40, 80 μmol/L) for 24 hours . After removal of 5-azacytidine, cells were cultured for another 4 weeks. RESULTS AND CONCLUSION: Before 5-azacytidine treatment, filament-like structures or particles were not observed in the cells, but the amount of cytoplasm was less and uniform, nuclear/cytoplasm ratio was high, cells exhibited typical fusiform appearance and grew in a swirl-like manner, and nucleolus was obvious. After treatment with 5-azacytidine for 24 hours, some cells died in each group, and typical fusiform appearance turned into stick-like or column-like appearance, especial y in the 40 and 80 μmol/L 5-azacytidine groups. Reverse transcription-PCR results showed that atrial natriuretic peptide and α-skeletal actin gene expression levels were detected on human umbilical cord mesenchymal stem cells after treatment with 2.5 or 40 μmol/L 5-azacytidine for 4 weeks or with 5, 10, 20 μmol/L 5-azacytidine for 1, 2, 3 and 4 weeks. These findings suggest that 5-azacytidine-induced human umbilical cord mesenchymal stem cells express the specific gene of myocardiocytes.% 背景：脐带来源的间充质干细胞进行自体心肌内移植，修复损伤心肌组织，是心血管研究领域的热点。目的：应用5-氮胞苷诱导人脐带间充质干细胞转化为心肌样细胞后进行鉴定，以确定心肌样细胞的结构、形态和功能。方法：分离培养人脐带间充质干细胞，在第2代细胞中分别加入浓度为2.5，5，10，20，40，80μmol/L 的5-氮胞苷，作用24 h 后除去，继续培养4周。结果与结论：5-氮胞苷诱导前，无细丝样结构、无颗粒，胞浆量均匀且少，核/浆比例高，细胞形态呈现典型的梭形，细胞呈漩祸样或同心圆生长，核内会见到较为明显的核仁；在5-氮胞苷处理24 h 之后，各组细胞都会出现部分死亡，失去典型的梭形形态，成为棍状或者柱状，40，80μmol/L 组细胞形态变化明显。反转录-聚合酶反应检测2.5，40μmol/L 组诱导4周，5，10，20μmol/L 组诱导1，2，3，4周时人脐带间充质干细胞心钠素、α-骨骼肌动蛋白基因表达呈阳性。提示经5-氮胞苷诱导的人脐带间充质干细胞表达心肌细胞的特定基因。
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