目的  探讨神经元素3（Ngn3）的过表达能否促进人脐带间充质干细胞（HUCMSCs）向胰岛素分泌细胞（IPCs）的诱导分化。  方法  分离培养HUCMSCs，流式细胞术鉴定其表面分子表达，成脂细胞、成骨细胞诱导鉴定其多向分化潜能；分阶段诱导HUCMSCs分化为IPCs，该过程包括低糖诱导和高糖诱导两阶段共21 d；实验分为两组，对照组仅进行分阶段诱导，实验组在分阶段诱导第6天感染载有目的基因Ngn3的慢病毒过表达载体，感染完成后继续诱导；电子显微镜观察诱导前、后细胞结构变化；两组细胞诱导完成后收集mRNA和蛋白质，通过Real-time PCR和Western blotting法比较诱导后两组细胞的胰岛素和肌腱膜纤维肉瘤癌基因同源物A（Mafa）表达情况；收集诱导中后期培养基上清液，ELISA测定C肽含量。   结果  成功分离HUCMSCs，细胞阳性表达CD105、CD90，阴性表达CD34、CD45，具有成脂、成骨分化能力；通过分阶段诱导将HUCMSCs向IPCs诱导，细胞阳性表达Mafa和胰岛素；实验组在诱导过程中成功过表达Ngn3；电子显微镜观察显示，实验组诱导细胞结构更为成熟；实验组IPCs胰岛素和Mafa的表达量明显高于对照组；诱导过程中实验组细胞分泌的C肽量高于对照组。   结论  慢病毒介导的Ngn3过表达提高了HUCMSCs向IPCs的诱导分化效率。

Objective  To investigate whether the overexpression of neurogenin 3（Ngn3）can promote the induced differentiation of human umbilical  cord mesenchymal stem cells（HUCMSCs）into insulinproducing cells（IPCs）.    Methods  HUCMSCs were isolated and cultured, identified by flow cytometry, and the differentiation potential was identified by adipogenesis and osteogenesis induction. HUCMSCs were induced into IPCs in different stages, including a low glucose induction stage and a high glucose induction stage. The experiment was divided into two groups, the control group was induced by the above scheme, while the experimental group was additionally infected the lentivirus overexpression vector carrying the target gene Ngn3 on the 6th day of the same induction process. After induction, the changes of cell structure were observed by electron microscope; mRNA and protein was collected and Real-time PCR and Western blotting were used to compare the expressions of insulin and musculoaponeurotic fibrosarcoma oncogene homolog A Mafa in the two groups; medium supernatant was collected and C-peptide content was determined by ELISA.   Results  HUCMSCs were successfully isolated with positive expression of CD105 and CD90 and negative expression of CD34 and CD45, which had adipogenic and osteogenic differentiation ability. Then, HUCMSCs were induced into IPCs by stage induction, and the cells expressed Mafa and insulin positively. Ngn3 was overexpressed in the experimental group during the induction. After induction, electron microscopy showed that the cell structure was more mature in the experimental group. The expression levels of insulin and Mafa in the experimental group were significantly higher than those in the control group. During the induction process, the amount of C-peptide secreted by the experimental group was higher than that of the control group.    Conclusion  Lentivirus-mediated Ngn3 overexpression improves the differentiation efficiency of HUCMSCs into IPCs.