Language：English   Publishing type：Research paper (scientific journal)  

DOI： 10.1016/j.ajpath.2020.02.005

Repository Public URL： https://hdl.handle.net/2324/7173546

Language：English   Publishing type：Research paper (scientific journal)  

Recent progress in direct lineage reprogramming has enabled the generation of induced hepatocyte-like (iHep) cells and revealed their potential as an alternative to hepatocytes for medical applications. However, the hepatic functions of iHep cells are insufficient compared with those of primary hepatocytes. Here, we show that cell-aggregate formation can rapidly induce growth arrest and hepatic maturation of iHep cells through activation of Hippo signaling. During formation of iHep cell aggregates, Yap inactivation is induced by actin reorganization and intercellular adhesion, leading to upregulation of Hnf1α expression in the absence of the Yap/Tead/Chd4 transcriptional repressor unit. Hnf1α then acts as a central transcription factor that regulates liver-enriched gene expression in iHep cell aggregates and induces functional differentiation of iHep cells. Moreover, iHep cell aggregates efficiently reconstitute injured liver tissues and support hepatic function after transplantation. Thus, iHep cell aggregates may provide insights into basic research and potential therapies for liver diseases.

DOI： 10.1016/j.celrep.2018.09.010

Language：Others  

Brief summary of the current protocols for generating intestinal organoids
© 2018 Japanese Society of Developmental Biologists The intestine has fundamental functions for the maintenance of homeostasis, including food digestion and nutrient/water absorption. Although the lumen of the intestine is always exposed to pathogens, intestinal epithelial cells form monolayer sheets that act as an epithelial barrier to prevent the invasion of pathogens. Thus, disruption of the intestinal epithelial barrier causes inflammatory bowel diseases. To investigate the details of these intractable intestinal diseases, it is necessary to analyze the characteristics of intestinal epithelial cells in vitro. However, it is difficult to maintain and propagate intestinal epithelial cells in culture. Recently, intestinal organoid culture systems have been established, in which differentiated intestinal epithelial lineage cells can be continuously produced from intestinal stem cells and form epithelial organoids with crypt-like structures in long-term culture. Moreover, intestinal epithelial organoids can be generated not only from intestinal tissue-derived cells, embryonic stem cells, and induced pluripotent stem cells, but also by inducing direct conversion of nonintestinal somatic cells into intestinal epithelial cells. These intestinal organoids can be used in basic studies for understanding the mechanisms underlying intestinal development and diseases and will be applied in future transplantation therapy and drug discovery to treat intestinal diseases.

DOI： 10.1111/dgd.12559

Language：English   Publishing type：Research paper (scientific journal)  

Intestinal organoids hold great promise as a valuable tool for studying and treating intestinal diseases. The currently available sources of human intestinal organoids, tissue fragments or pluripotent stem cells, involve invasive procedures or complex differentiation protocols, respectively. Here, we show that a set of four transcription factors, Hnf4 alpha, Foxa3, Gata6, and Cdx2, can directly reprogram mouse fibroblasts to acquire the identity of fetal intestine-derived progenitor cells (FIPCs). These induced FIPCs (iFIPCs) form spherical organoids that develop into adult-type budding organoids containing cells with intestinal stem cell properties. The resulting stem cells produce all intestinal epithelial cell lineages and undergo self-renewing cell divisions. After transplantation, the induced spherical and budding organoids can reconstitute colonic and intestinal epithelia, respectively. The same combination of four defined transcription factors can also induce human iFIPCs. This alternative approach for producing intestinal organoids may well facilitate application for disease analysis and therapy development.

DOI： 10.1016/j.stem.2017.08.020

Repository Public URL： https://hdl.handle.net/2324/7172621

Language：English   Publishing type：Research paper (scientific journal)  

Hepatic progenitor cells (HPCs) appear in response to several types of chronic injury in the human and rodent liver that often develop into liver fibrosis, cirrhosis, and primary liver cancers. However, the contribution of HPCs to the pathogenesis and progression of such liver diseases remains controversial. HPCs are generally defined as cells that can differentiate into hepatocytes and cholangiocytes. In this study, however, we found that HPCs isolated from the chronically injured liver can also give rise to myofibroblasts as a third type of descendant. While myofibroblast differentiation from HPCs is not significant in culture, during tumor development, HPCs can contribute to the formation of the tumor microenvironment by producing abundant myofibroblasts that might form a niche for tumor growth and survival. Thus, HPCs can be redefined as cells with a potential for differentiation into myofibroblasts that is specifically activated during tumor formation.

DOI： 10.1016/j.stemcr.2016.11.002

Language：English   Publishing type：Research paper (scientific journal)  

Intrahepatic cholangiocarcinoma (ICC) is a malignant epithelial neoplasm composed of cells resembling cholangiocytes that line the intrahepatic bile ducts in portal areas of the hepatic lobule. Although ICC has been defined as a tumor arising from cholangiocyte transformation, recent evidence from genetic lineage-tracing experiments has indicated that hepatocytes can be a cellular origin of ICC by directly changing their fate to that of biliary lineage cells. Notch signaling has been identified as an essential factor for hepatocyte conversion into biliary lineage cells at the onset of ICC. However, the mechanisms underlying Notch signal activation in hepatocytes remain unclear. Here, using a mouse model of ICC, we found that hepatic macrophages called Kupffer cells transiently congregate around the central veins in the liver and express the Notch ligand Jagged-1 coincident with Notch activation in pericentral hepatocytes. Depletion of Kupffer cells prevents the Notch-mediated cell-fate conversion of hepatocytes to biliary lineage cells, inducing hepatocyte apoptosis and increasing mortality in mice. These findings will be useful for uncovering the pathogenic mechanism of ICC and developing prevenient and therapeutic strategies for this refractory disease.

DOI： 10.1038/srep34691

Language：English   Publishing type：Research paper (scientific journal)  

In liver development, hepatoblasts that act as hepatic stem/progenitor cells proliferate and differentiate into both hepatocytes and cholangiocytes to form liver tissues. Although numerous factors contribute to this event, little is known about the roles of microRNAs in hepatoblast proliferation and differentiation. In this study, we focused on the lineage-28 (Lin28) family proteins, which are required for microRNA regulation in pluripotent stem cells and cancer cells, and investigated their roles as regulatory factors for the properties of hepatoblasts. Conclusion: Lin28b was specifically expressed in hepatoblasts, and its suppression induced growth arrest and cholangiocyte differentiation of hepatoblasts; mechanistically, Lin28b positively regulates the expression of Lin28b itself and cell cycle-related proteins in hepatoblasts by suppressing the maturation of target microRNAs, lethal-7b and miR-125a/b, enabling maintenance of the stem cell properties of hepatoblasts, such as their capabilities for proliferation and bi-lineage differentiation, during liver development.

DOI： 10.1002/hep.28548

Language：English  

Rapid cell-fate conversion of mouse fibroblasts into hepatocyte-like cells
Recent progress in studies on direct cell-fate conversion of differentiated somatic cells into other cell types, which is known as "direct reprogramming", is expected to lead to innovations in health care. In our previous study, we found that three specific combinations of two transcription factors, comprising Hnf4α plus Foxa1, Foxa2, or Foxa3, were able to induce conversion of mouse fibroblasts into functional hepatocyte-like cells. These induced hepatocyte-like (iHep) cells will be useful for developing regenerative therapies for liver diseases and examining the pharmacological effects of drugs. However, to evaluate the potential utility of iHep cells, the phenomena involved in the direct conversion of fibroblasts into iHep cells should be examined in detail. Thus, in this study, we sequentially analyzed the early stage of fibroblast conversion into iHep cells after infection with retroviruses expressing Hnf4α and Foxa3. Our data demonstrated that the conversion into iHep cells began within 2 days after introduction of the transgenes into fibroblasts, and the number of iHep cells increased gradually as the culture progressed. The rapid cell-fate conversion of fibroblasts into iHep cells and stable expansion of iHep cells are two pieces of evidence suggesting the utility of iHep cells for cell transplantation therapy, bioartificial liver development, and screening of drugs for patients with liver diseases, which require many hepatocytes within a short period of time.

DOI： 10.2492/inflammregen.34.211

Language：Others  

Acquisition of lipid metabolic capability in hepatocyte-like cells directly induced from mouse fibroblasts.

DOI： 10.3389/fcell.2014.00043

Language：Japanese  

Country：Other  

Language：English  

Country：Other  

Analysis of hepatic lipid metabolism using iHep cells

Language：English  

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Analysis of reprogramming process from fibroblasts to induced hepatocyte-like cells

Language：Japanese  

Country：Other  

Language：English  

Country：Other  

nalysis of hepatic lipid metabolism using iHep cells

Language：English  

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Induction of functional hepatocytes from mouse fibroblasts

Language：Japanese  

Country：Other