Laboratory of Biochemistry and Molecular Biology, Graduate School of Pharmaceutical Sciences, Osaka University, Osaka, 565-0871, Japan.
Laboratory of Hepatocyte Regulation, National Institutes of Biomedical Innovation, Health and Nutrition, Osaka, 567-0085, Japan.
Sci Rep. 2019 Mar 6;9(1):3713. doi: 10.1038/s41598-019-40305-2.
Human induced pluripotent stem cell-derived hepatocyte-like cells are expected to be utilized in pharmaceutical research and regenerative medicine. In general, human induced pluripotent stem (iPS) cells are differentiated into hepatocyte-like cells through definitive endoderm cells and hepatoblast-like cells using various growth factors that are essential for liver development. Although recombinant bone morphogenetic proteins (BMPs) and fibroblast growth factors (FGFs) are widely used in the hepatoblast differentiation, hepatoblast differentiation process has not been fully modified. In this study, we examined the roles of BMPs and FGFs in the hepatoblast differentiation from human iPS cells. Surprisingly, the gene expression levels of hepatoblast markers were upregulated by the removal of FGFs. In addition, the percentages of hepatoblast markers-positive cells were increased by the removal of FGFs. Furthermore, the hepatocyte differentiation potency was also significantly increased by the removal of FGFs. To examine whether FGF signals are completely unnecessary for the hepatoblast differentiation, the expression levels of endogenous FGF ligands and receptors were examined. The definitive endoderm cells highly expressed the FGF ligand, FGF2, and the FGF receptor, FGFR1. To examine the role of endogenous FGF signals, an FGFR inhibitor was treated during the hepatoblast differentiation. The hepatoblast differentiation was promoted by using FGFR inhibitor, suggesting that endogenous FGF signals are also unnecessary for the hepatoblast differentiation. In conclusion, we found that FGF signals are not essential for hepatoblast differentiation. We believe that our finding will be useful for generating functional hepatocyte-like cells for medical applications.
人诱导多能干细胞衍生的肝细胞样细胞有望用于药物研究和再生医学。通常，人诱导多能干细胞（iPS）细胞通过各种必需的生长因子，从确定内胚层细胞和肝前体细胞分化为肝细胞样细胞，这些生长因子对肝脏发育至关重要。尽管重组骨形态发生蛋白（BMPs）和成纤维细胞生长因子（FGFs）广泛用于肝母细胞分化，但肝母细胞分化过程尚未完全修饰。在这项研究中，我们研究了 BMPs 和 FGFs 在人 iPS 细胞向肝母细胞分化中的作用。令人惊讶的是，去除 FGFs 可上调肝母细胞标志物的基因表达水平。此外，去除 FGFs 还可增加肝母细胞标志物阳性细胞的百分比。此外，去除 FGFs 还可显著增加肝细胞分化潜能。为了检查 FGF 信号是否完全不需要肝母细胞分化，我们检查了内源性 FGF 配体和受体的表达水平。确定内胚层细胞高度表达 FGF 配体 FGF2 和 FGF 受体 FGFR1。为了检查内源性 FGF 信号的作用，在肝母细胞分化期间用 FGFR 抑制剂进行处理。使用 FGFR 抑制剂促进肝母细胞分化，表明内源性 FGF 信号对于肝母细胞分化也是不必要的。总之，我们发现 FGF 信号对于肝母细胞分化不是必需的。我们相信，我们的发现将有助于为医学应用生成功能性肝细胞样细胞。
