ABSTRACT
In this study, we aimed to elucidate the effects and mechanism of action of valproic acid on hepatic differentiation from human induced pluripotent stem cell-derived hepatic progenitor cells. Human induced pluripotent stem cells were differentiated into endodermal cells in the presence of activin A and then into hepatic progenitor cells using dimethyl sulfoxide. Hepatic progenitor cells were matured in the presence of hepatocyte growth factor, oncostatin M, and dexamethasone with valproic acid that was added during the maturation process. After 25 days of differentiation, cells expressed hepatic marker genes and drug-metabolizing enzymes and exhibited drug-metabolizing enzyme activities. These expression levels and activities were increased by treatment with valproic acid, the timing and duration of which were important parameters to promote differentiation from human induced pluripotent stem cell-derived hepatic progenitor cells into hepatocytes. Valproic acid inhibited histone deacetylase activity during differentiation of human induced pluripotent stem cells, and other histone deacetylase inhibitors also enhanced differentiation into hepatocytes. In conclusion, histone deacetylase inhibitors such as valproic acid can be used to promote hepatic differentiation from human induced pluripotent stem cell-derived hepatic progenitor cells.
Subject(s)
Cell Differentiation/drug effects , Hepatocytes/cytology , Histone Deacetylase Inhibitors/pharmacology , Induced Pluripotent Stem Cells/cytology , Valproic Acid/pharmacology , Adult , Aged , Albumins/metabolism , Biomarkers/metabolism , Cell Line , Cell Shape/drug effects , Cytochrome P-450 CYP3A/biosynthesis , Cytochrome P-450 CYP3A/genetics , Enzyme Induction/drug effects , Fluorescent Antibody Technique , Hepatocytes/drug effects , Humans , Inactivation, Metabolic/drug effects , Induced Pluripotent Stem Cells/drug effects , Induced Pluripotent Stem Cells/enzymology , Middle Aged , RNA, Messenger/genetics , RNA, Messenger/metabolism , Small Molecule Libraries/pharmacology , Staining and Labeling , Substrate Specificity/drug effectsABSTRACT
This study aimed to establish culture conditions which are able to give the differentiation of induced pluripotent (iPS) cells to hepatocytes. To this end, we examined the usefulness of a culture medium containing the components involved in the intermediary metabolism in the liver. More specifically, we examined the effect of the "modified L-15 medium" containing galactose, phenylalanine and ornitine, but deprived of glucose, tyrosine, arginine and pyruvic acid. The medium was altered according to changes in the expression of enzymes that participate in liver-specific pathways. After 25 days of differentiation, the differentiated cells expressed hepatocyte markers and drug-metabolizing enzymes. These expression levels were increased using modified L-15 medium. The survival of human fetal liver cells and the death of human fibroblasts were observed during culture in modified L-15 medium. Most of the cells that differentiated from human iPS cells using modified L-15 medium were stained by anti-human albumin antibody. These results suggest that iPS cells can be converted to high purity-differentiated hepatocytes by cultivating them in modified L-15 medium.
