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目的采用单层分步法诱导人胚胎干细胞(human embryonic stem cells,hESCs)分化为肝样细胞,建立hESCs分化为肝细胞的诱导体系。方法将hESC株H1细胞接种到Matrigel包被的培养板上,早期(细胞贴壁4d后)加入含有细胞因子活化素A(Activin A)的分化液诱导5d;中期将诱导液换为含FGF-1和BMP-4的肝分化液诱导6d;最后添加肝细胞生长因子(hepatocyte growth factor,HGF)和制癌蛋白M(Oncostatin M,OSM)继续诱导分化5～7d。采用免疫细胞化学染色、RT-PCR、过碘酸-雪夫(Periodicacid-Schiff,PAS)反应鉴定分化细胞的性质。结果经Activin A、FGF-1、BMP-4、HGF和OSM连续诱导的hESCs呈多角形、卵圆形或圆形,排列紧密;部分细胞出现二核或三核,呈现肝细胞所特有的形态。分化细胞在诱导早期表达SOX17、叉头框(Forkhead box,FOX)A2、GATA-4,中期表达甲胎蛋白(αfetoprotein,AFP)、白蛋白、角蛋白18,晚期表达成熟肝细胞特异性基因乙醇脱氢酶1C、细胞色素P4501B1。免疫细胞化学染色示,Activin A诱导后,细胞呈SOX17和FOXA2阳性;经FGF-1和BMP-4诱导后,呈AFP和α1抗胰蛋白酶阳性。HGF和OSM诱导后,PAS糖原染色检测阳性。结论采用单层分步法逐步添加细胞因子,可诱导hESCs分化为肝样细胞。该分化体系可为肝细胞移植、肝组织工程等临床治疗提供一个有效的细胞来源。
OBJECTIVE: To induce human embryonic stem cells (hESCs) to differentiate into hepatocyte-like cells by a single-staged fractionation method and establish an induction system for hESCs to differentiate into hepatocytes. Methods The hESC strain H1 cells were inoculated into Matrigel coated plates and induced by differentiation medium containing Activin A at early stage (after 4 days of adhering to the cells). The medium was changed to medium containing FGF- 1 and BMP-4 were induced for 6 days. Finally, hepatocyte growth factor (HGF) and oncostatin M (OSM) were added to induce differentiation for 5-7 days. The characteristics of differentiated cells were identified by immunocytochemistry, RT-PCR and Periodic acid-Schiff reaction (PAS). Results The hESCs induced by Activin A, FGF-1, BMP-4, HGF and OSM were polygonal, oval or round, closely arranged. Some of the cells appeared two or three nuclei, which showed the characteristic of hepatocytes . Differentiated cells induced early expression of SOX17, Forkhead box (FOX) A2, GATA-4, alphafetoprotein (AFP), albumin and keratin 18 in metaphase and mature hepatocyte-specific gene ethanol Dehydrogenase 1C, Cytochrome P4501B1. Immunocytochemical staining showed that after induction with Activin A, the cells were positive for SOX17 and FOXA2; AFP and α1 antitrypsin were positive after induced by FGF-1 and BMP-4. After HGF and OSM induction, PAS glycogen staining was positive. Conclusion The hESCs can be induced to differentiate into hepatocyte-like cells by adding cytokines step by step. The differentiation system for liver cell transplantation, liver tissue engineering and other clinical treatment to provide an effective source of cells.