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Core promoter recognition complex changes accompany liver development. Proc Natl Acad Sci U S A 2011; 108:3906-11. [PMID: 21368148 DOI: 10.1073/pnas.1100640108] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023] Open
Abstract
Recent studies of several key developmental transitions have brought into question the long held view of the basal transcriptional apparatus as ubiquitous and invariant. In an effort to better understand the role of core promoter recognition and coactivator complex switching in cellular differentiation, we have examined changes in transcription factor IID (TFIID) and cofactor required for Sp1 activation/Mediator during mouse liver development. Here we show that the differentiation of fetal liver progenitors to adult hepatocytes involves a wholesale depletion of canonical cofactor required for Sp1 activation/Mediator and TFIID complexes at both the RNA and protein level, and that this alteration likely involves silencing of transcription factor promoters as well as protein degradation. It will be intriguing for future studies to determine if a novel and as yet unknown core promoter recognition complex takes the place of TFIID in adult hepatocytes and to uncover the mechanisms that down-regulate TFIID during this critical developmental transition.
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Tanaka M, Itoh T, Tanimizu N, Miyajima A. Liver stem/progenitor cells: their characteristics and regulatory mechanisms. J Biochem 2011; 149:231-9. [PMID: 21217146 DOI: 10.1093/jb/mvr001] [Citation(s) in RCA: 86] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Liver stem cells give rise to both hepatocytes and bile duct epithelial cells also known as cholangiocytes. During liver development hepatoblasts emerge from the foregut endoderm and give rise to both cell types. Colony-forming cells are present in the liver primordium and clonally expanded cells differentiate into either hepatocytes or cholangiocytes depending on culture conditions, showing stem cell characteristics. The growth and differentiation of hepatoblasts are regulated by various extrinsic signals. For example, periportal mesenchymal cells provide a cue for bipotential hepatoblasts to become cholangiocytes, and mesothelial cells covering the parenchyma support the expansion of foetal hepatocytes by producing growth factors. The adult liver has an extraordinary capacity to regenerate, and after 70% hepatectomy the liver recovers its original mass by replication of the remaining hepatocytes without the activation of liver stem cells. However, in certain types of liver injury models, liver stem/progenitor-like cells, known as oval cells in rodents, proliferate around the portal vein, while the roles of such cells in liver regeneration remain a matter of debate. Clonogenic and bipotential cells are also present in the normal adult liver. In this minireview we describe recent studies on liver stem/progenitor cells by focusing on extracellular signals.
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Affiliation(s)
- Minoru Tanaka
- Institute of Molecular and Cellular Biosciences, The University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo, Japan
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53
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Sakai H, Tagawa YI, Tamai M, Motoyama H, Ogawa S, Soeda J, Nakata T, Miyagawa S. Isolation and characterization of portal branch ligation-stimulated Hmga2-positive bipotent hepatic progenitor cells. Biochem Biophys Res Commun 2010; 403:298-304. [PMID: 21075076 DOI: 10.1016/j.bbrc.2010.11.021] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2010] [Accepted: 11/09/2010] [Indexed: 12/16/2022]
Abstract
Hepatic stem/progenitor cells are one of several cell sources that show promise for restoration of liver mass and function. Although hepatic progenitor cells (HPCs), including oval cells, are induced by administration of certain hepatotoxins in experimental animals, such a strategy would be inappropriate in a clinical setting. Here, we investigated the possibility of isolating HPCs in a portal branch-ligated liver model without administration of any chemical agents. A non-parenchymal cell fraction was prepared from the portal branch-ligated or non-ligated lobe, and seeded onto plates coated with laminin. Most of the cells died, but a small number were able to proliferate. These proliferating cells were cloned as portal branch ligation-stimulated hepatic cells (PBLHCs) by the limiting dilution method. The PBLHCs expressed cytokeratin19, albumin, and Hmga2. The PBLHCs exhibited metabolic functions such as detoxification of ammonium ions and synthesis of urea on Matrigel-coated plates in the presence of oncostatin M. In Matrigel mixed with type I collagen, the PBLHCs became rearranged into cystic and tubular structures. Immunohistochemical staining demonstrated the presence of Hmga2-positive cells around the interlobular bile ducts in the portal branch-ligated liver lobes. In conclusion, successful isolation of bipotent hepatic progenitor cell clones, PBLHCs, from the portal branch-ligated liver lobes of mice provides the possibility of future clinical application of portal vein ligation to induce hepatic progenitor cells.
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Affiliation(s)
- Hiroshi Sakai
- Department of Surgery, Shinshu University School of Medicine, 3-1-1 Asahi, Matsumoto, Nagano 390-8621, Japan
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The polycomb group gene product Ezh2 regulates proliferation and differentiation of murine hepatic stem/progenitor cells. J Hepatol 2010; 52:854-63. [PMID: 20395008 DOI: 10.1016/j.jhep.2010.01.027] [Citation(s) in RCA: 61] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/18/2009] [Revised: 01/12/2010] [Accepted: 01/14/2010] [Indexed: 01/21/2023]
Abstract
BACKGROUND & AIMS Polycomb group proteins initiate and maintain gene silencing through chromatin modifications and contribute to the maintenance of self-renewal in a variety of stem cells. Among polycomb repressive complexes (PRCs), PRC2 initiates gene silencing by methylating histone H3 lysine 27, and PRC1 maintains gene silencing through mono-ubiquitination of histone H2A lysine 119. We have previously shown that Bmi1, a core component of PRC1, tightly regulates the self-renewal of hepatic stem/progenitor cells. METHODS In this study, we conducted lentivirus-mediated knockdown of Ezh2 to characterise the function of Ezh2, a major component of PRC2, in hepatic stem/progenitor cells. RESULTS Loss of Ezh2 function in embryonic murine hepatic stem/progenitor cells severely impaired proliferation and self-renewal capability. This effect was more prominent than that of Bmi1-knockdown and was partially abrogated by the deletion of both Ink4a and Arf, major targets of PRC1 and PRC2. Importantly, Ezh2-knockdown but not Bmi1-knockdown promoted the differentiation and terminal maturation of hepatocytes, followed by the up-regulation of several transcriptional regulators of hepatocyte differentiation. CONCLUSIONS Our findings indicate that Ezh2 plays an essential role in the maintenance of both the proliferative and self-renewal capacity of hepatic stem/progenitor cells and the full execution of their differentiation.
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Yu F, Hao X, Zhao H, Ge C, Yao M, Yang S, Li J. Delta-like 1 contributes to cell growth by increasing the interferon-inducible protein 16 expression in hepatocellular carcinoma. Liver Int 2010; 30:703-14. [PMID: 20214740 DOI: 10.1111/j.1478-3231.2010.02214.x] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/13/2023]
Abstract
BACKGROUND Delta-like 1 (DLK1), a fetal liver stem cell marker, is strongly expressed in human and rodent fetal liver, but not in adult liver. Notably, dysregulation of DLK1 was found in some human hepatocellular carcinomas (HCC). However, the effect of DLK1 on HCC cell growth and its underlying mechanism are still largely unknown. AIMS To (i) assess the expression of DLK1 in human HCC and adjacent liver tissues and human HCC cell lines; (ii) evaluate the effect of DLK1 on SMMC-7721, Huh7 HCC cell growth in vitro and in vivo; and (iii) explore the potential mechanism of DLK1 that regulates HCC cell growth. METHODS The expression of DLK1 mRNA and protein were detected using reverse transcriptase-polymerase chain reaction and immunohistochemistry respectively. The effect of DLK1 on the proliferation of SMMC-7721 and Huh7 cells was evaluated by colony formation and tumour xenograft assay. The differential expression profiles of DLK1-overexpressing SMMC-7721 cells and control cells were compared using HG-U133 Plus 2 Genechip. The cell cycle distribution of DLK1 forced expressing cells was comparatively analysed. RESULTS Upregulation of DLK1 was observed in 41 of 57 (71.9%) human HCC samples. Ectopic expression of DLK1 promoted cell proliferation, colony formation and tumorigenicity in SMMC-7721 and Huh7 cells. DLK1 upregulated the expression of interferon-inducible protein 16 (IFI16) and its promoter transcriptional activity, decreased p21waf1/cip1 and induced cell cycle acceleration. However, silencing of IFI16 using small interfering RNA abrogated DLK1-induced proliferation in these cells. CONCLUSIONS IFI16 may be an essential downstream target of DLK1 in HCC cells and required for DLK1-induced cell proliferation.
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Affiliation(s)
- Feng Yu
- Institute of Life Sciences, Jiangsu University, Zhenjiang, China
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56
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Fetal liver hepatic progenitors are supportive stromal cells for hematopoietic stem cells. Proc Natl Acad Sci U S A 2010; 107:7799-804. [PMID: 20385801 DOI: 10.1073/pnas.1003586107] [Citation(s) in RCA: 105] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Previously we showed that the ~2% of fetal liver cells reactive with an anti-CD3epsilon monoclonal antibody support ex vivo expansion of both fetal liver and bone marrow hematopoietic stem cells (HSCs); these cells express two proteins important for HSC ex vivo expansion, IGF2, and angiopoietin-like 3. Here we show that these cells do not express any CD3 protein and are not T cells; rather, we purified these HSC-supportive stromal cells based on the surface phenotype of SCF(+)DLK(+). Competitive repopulating experiments show that SCF(+)DLK(+) cells support the maintenance of HSCs in ex vivo culture. These are the principal fetal liver cells that express not only angiopoietin-like 3 and IGF2, but also SCF and thrombopoietin, two other growth factors important for HSC expansion. They are also the principal fetal liver cells that express CXCL12, a factor required for HSC homing, and also alpha-fetoprotein (AFP), indicating that they are fetal hepatic stem or progenitor cells. Immunocytochemistry shows that >93% of the SCF(+) cells express DLK and Angptl3, and a portion of SCF(+) cells also expresses CXCL12. Thus SCF(+)DLK(+) cells are a highly homogenous population that express a complete set of factors for HSC expansion and are likely the primary stromal cells that support HSC expansion in the fetal liver.
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Binding of APC and dishevelled mediates Wnt5a-regulated focal adhesion dynamics in migrating cells. EMBO J 2010; 29:1192-204. [PMID: 20224554 DOI: 10.1038/emboj.2010.26] [Citation(s) in RCA: 82] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2009] [Accepted: 02/09/2010] [Indexed: 01/28/2023] Open
Abstract
Wnt5a is a representative ligand that activates the Wnt/beta-catenin-independent pathway, resulting in the regulation of cell adhesion, migration, and polarity, but its molecular mechanism is poorly understood. This report shows that Dishevelled (Dvl) binds to adenomatous polyposis coli (APC) gene product, and this binding is enhanced by Wnt5a. Dvl was involved in the stabilization of the plus end dynamics of microtubules as well as APC. Frizzled2 (Fz2) was present with Wnt5a at the leading edge of migrating cells and formed a complex with APC through Dvl. Fz2 also interacted with integrins at the leading edge, and Dvl and APC associated with and activated focal adhesion kinase and paxillin. The binding of APC to Dvl enhanced the localization of paxillin to the leading edge and was involved in Wnt5a-dependent focal adhesion turnover. Furthermore, this new Wnt5a signalling pathway was important for the epithelial morphogenesis in the three-dimensional culture. These results suggest that the functional and physical interaction of Dvl and APC is involved in Wnt5a/Fz2-dependent focal adhesion dynamics during cell migration and epithelial morphogenesis.
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Miyaoka Y, Tanaka M, Imamura T, Takada S, Miyajima A. A novel regulatory mechanism for Fgf18 signaling involving cysteine-rich FGF receptor (Cfr) and delta-like protein (Dlk). Development 2010; 137:159-67. [PMID: 20023171 DOI: 10.1242/dev.041574] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Fibroblast growth factors (FGFs) transduce signals through FGF receptors (FGFRs) and have pleiotropic functions. Besides signal-transducing FGFRs, cysteine-rich FGF receptor (Cfr; Glg1) is also known to bind some FGFs, although its physiological functions remain unknown. In this study, we generated Cfr-deficient mice and found that some of them die perinatally, and show growth retardation, tail malformation and cleft palate. These phenotypes are strikingly similar to those of Fgf18-deficient mice, and we revealed interaction between Cfr and Fgf18 both genetically and physically, suggesting functional cooperation. Consistently, introduction of Cfr facilitated Fgf18-dependent proliferation of Ba/F3 cells expressing Fgfr3c. In addition, we uncovered binding between Cfr and delta-like protein (Dlk), and noticed that Cfr-deficient mice are also similar to Dlk-transgenic mice, indicating that Cfr and Dlk function in opposite ways. Interestingly, we also found that Dlk interrupts the binding between Cfr and Fgf18. Thus, the Fgf18 signaling pathway seems to be finely tuned by Cfr and Dlk for skeletal development. This study reveals a novel regulatory mechanism for Fgf18 signaling involving Cfr and Dlk.
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Affiliation(s)
- Yuichiro Miyaoka
- Laboratory of Cell Growth and Differentiation, Institute of Molecular and Cellular Biosciences, The University of Tokyo, Yayoi, Bunkyo-ku, Tokyo 113-0032, Japan
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59
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Potentials of regenerative medicine for liver disease. Surg Today 2009; 39:1019-25. [PMID: 19997795 DOI: 10.1007/s00595-009-4056-z] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2009] [Accepted: 04/29/2009] [Indexed: 01/04/2023]
Abstract
Liver transplantation is still the only effective treatment for end-stage liver disease. However, because of the serious worldwide shortage of donated organs, an alternative cellular therapy would be desirable. Animal studies and preclinical trials have indicated that hepatocyte transplantation can serve as an alternative to liver transplantation. Unfortunately, however, the harvesting of hepatocytes is associated with the same problem as organ transplantation, i.e., a lack of a suitable cell source. Therefore, current stem cell technology, which is attempting to establish an unlimited supply of hepatocytes, would facilitate the clinical application of hepatocyte transplantation. This review summarizes current knowledge of embryonic and adult stem cell differentiation into hepatocytes and discusses how liver stem cells could be applied clinically in the future.
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60
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Okabe M, Tsukahara Y, Tanaka M, Suzuki K, Saito S, Kamiya Y, Tsujimura T, Nakamura K, Miyajima A. Potential hepatic stem cells reside in EpCAM+ cells of normal and injured mouse liver. Development 2009; 136:1951-60. [PMID: 19429791 DOI: 10.1242/dev.031369] [Citation(s) in RCA: 230] [Impact Index Per Article: 15.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Hepatic oval cells are considered to be facultative hepatic stem cells (HSCs) that differentiate into hepatocytes and cholangiocytes in severely injured liver. Hepatic oval cells have also been implicated in tumorigenesis. However, their nature and origin remain elusive. To isolate and characterize mouse oval cells, we searched for cell surface molecules expressed on oval cells and analyzed their nature at the single-cell level by flow cytometric analysis and in the in vitro colony formation assay. We demonstrate that epithelial cell adhesion molecule (EpCAM) is expressed in both mouse normal cholangiocytes and oval cells, whereas its related protein, TROP2, is expressed exclusively in oval cells, establishing TROP2 as a novel marker to distinguish oval cells from normal cholangiocytes. EpCAM(+) cells isolated from injured liver proliferate to form colonies in vitro, and the clonally expanded cells differentiate into hepatocytes and cholangiocytes, suggesting that the oval cell fraction contains potential HSCs. Interestingly, such cells with HSC characteristics exist among EpCAM(+) cells of normal liver. Intriguingly, comparison of the colony formation of EpCAM(+) cells in normal and injured liver reveals little difference in the number of potential HSCs, strongly suggesting that most proliferating mouse oval cells represent transit-amplifying cells rather than HSCs.
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Affiliation(s)
- Mayuko Okabe
- Laboratory of Cell Growth and Differentiation, Institute of Molecular and Cellular Biosciences, The University of Tokyo, Tokyo 113-0032, Japan
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61
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Dong XJ, Zhang GR, Zhou QJ, Pan RL, Chen Y, Xiang LX, Shao JZ. Direct hepatic differentiation of mouse embryonic stem cells induced by valproic acid and cytokines. World J Gastroenterol 2009; 15:5165-75. [PMID: 19891015 PMCID: PMC2773895 DOI: 10.3748/wjg.15.5165] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
AIM: To develop a protocol for direct hepatic lineage differentiation from early developmental progenitors to a population of mature hepatocytes.
METHODS: Hepatic progenitor cells and then mature hepatocytes from mouse embryonic stem (ES) cells were obtained in a sequential manner, induced by valproic acid (VPA) and cytokines (hepatocyte growth factor, epidermal growth factor and insulin). Morphological changes of the differentiated cells were examined by phase-contrast microscopy and electron microscopy. Reverse transcription polymerase chain reaction and immunocytochemical analyses were used to evaluate the gene expression profiles of the VPA-induced hepatic progenitors and the hepatic progenitor-derived hepatocytes. Glycogen storage, cytochrome P450 activity, transplantation assay, differentiation of bile duct-like structures and tumorigenic analyses were performed for the functional identification of the differentiated cells. Furthermore, FACS and electron microscopy were used for the analyses of cell cycle profile and apoptosis in VPA-induced hepatic differentiated cells.
RESULTS: Based on the combination of VPA and cytokines, mouse ES cells differentiated into a uniform and homogeneous cell population of hepatic progenitor cells and then matured into functional hepatocytes. The progenitor population shared several characteristics with ES cells and hepatic stem/progenitor cells, and represented a novel progenitor cell between ES and hepatic oval cells in embryonic development. The differentiated hepatocytes from progenitor cells shared typical characteristics with mature hepatocytes, including the patterns of gene expression, immunological markers, in vitro hepatocyte functions and in vivo capacity to restore acute-damaged liver function. In addition, the differentiation of hepatic progenitor cells from ES cells was accompanied by significant cell cycle arrest and selective survival of differentiating cells towards hepatic lineages.
CONCLUSION: Hepatic cells of different developmental stages from early progenitors to matured hepatocytes can be acquired in the appropriate order based on sequential induction with VPA and cytokines.
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Kamiya A, Kakinuma S, Yamazaki Y, Nakauchi H. Enrichment and clonal culture of progenitor cells during mouse postnatal liver development in mice. Gastroenterology 2009; 137:1114-26, 1126.e1-14. [PMID: 19524574 DOI: 10.1053/j.gastro.2009.06.001] [Citation(s) in RCA: 85] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/13/2008] [Revised: 06/03/2009] [Accepted: 06/08/2009] [Indexed: 12/17/2022]
Abstract
BACKGROUND & AIMS Stem and progenitor cells exist in normal postnatal livers. However, it has not been possible to clonally isolate or analyze postnatal liver stem/progenitor-like cells (PLSCs) derived from noninjured livers because of a lack of specific surface markers. This study aimed to establish a primary culture system for clone-sorted PLSCs. METHODS To investigate proliferation and differentiation of PLSCs, subpopulations of nonparenchymal cells derived from noninjured livers were purified and cultured using a single-cell culture system. Cells were grown in fetal liver cell-derived conditioned medium in the presence of the Rho-associated kinase (ROCK) inhibitor Y-27632. RESULTS We identified CD13 and CD133 as markers expressed on the PLSC-containing population in noninjured livers and established an efficient single-cell culture system to clonally analyze PLSCs. Culture of PLSCs is difficult, even using conditioned medium, but the addition of Y-27632 increased PLSC cell proliferation. The proportion of progenitor cells among nonparenchymal cells decreased during postnatal liver development; however, a PLSC population was still preserved in 3-month-old mice. Long-term cultivated cells derived from clone-sorted cells in normal livers were established and were called normal-liver-derived stem-like cells (NLS cells). NLS cells could differentiate into hepatocyte-like and cholangiocyte-like cells under appropriate culture conditions and underwent self-renewal-like activity in serial reclone-sorted culture. CD13 and CD133 were expressed on progenitor cells derived from fetal and postnatal liver, whereas CD49f (integrin alpha6 subunit) was strongly expressed only on PLSCs. CONCLUSIONS These results demonstrate the presence of progenitor cells in the CD13(+)CD49f(+)CD133(+) subpopulation of nonhematopoietic cells derived from noninjured postnatal livers.
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Affiliation(s)
- Akihide Kamiya
- Division of Stem Cell Therapy, Center for Stem Cell Biology and Regenerative Medicine, Institute of Medical Science, University of Tokyo, Tokyo, Japan.
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63
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Dalgetty DM, Medine CN, Iredale JP, Hay DC. Progress and future challenges in stem cell-derived liver technologies. Am J Physiol Gastrointest Liver Physiol 2009; 297:G241-8. [PMID: 19520740 DOI: 10.1152/ajpgi.00138.2009] [Citation(s) in RCA: 70] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
The emergence of regenerative medicine has led to significant advances in the identification and understanding of human stem cells and adult progenitor cells. Both cell populations exhibit plasticity and theoretically offer a potential source of somatic cells in large numbers. Such a resource has an important role to play in the understanding of human development, in modeling human disease and drug toxicity, and in the generation of somatic cells in large numbers for cell-based therapies. Presently, liver transplantation is the only effective treatment for end-stage liver disease. Although this procedure can be carried out with high levels of success, the routine transplant of livers is severely limited by organ donor availability. As a result, attention has focused on the ability to restore liver mass and function by alternative approaches ranging from the bioartificial device to transplantation of human hepatocytes. In this review we will focus on the generation of human hepatic endoderm from different stem/progenitor cell populations with a view to its utility in regenerative medicine.
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Affiliation(s)
- Donna M Dalgetty
- Medical Research Council Centre for Regenerative Medicine, University of Edinburgh, Edinburgh, Scotland, UK
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64
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Abstract
Morbidity and mortality from cirrhosis is increasing rapidly in the world. Currently, orthotopic liver transplantation is the only definitive therapeutic option. However, its clinical use is limited, because of poor long-term graft survival, donor organ shortage and high costs associated with the procedure. Stem cell replacement strategies are therefore being investigated as an attractive alternative approach to liver repair and regeneration. In this review we discuss recent preclinical and clinical investigations that explore the therapeutic potential of stem cells in repair of liver injuries. Several types of stem cells. including embryonic stem cells, haematopoietic stem cells and mesenchymal stem cells, can be induced to differentiate into hepatocyte-like cells by defined culture conditions in vitro. Stem cell transplantation has been shown to significantly improve liver function and increase animal survival in experimentally-induced liver-injury models. Moreover, several pilot clinical studies have reported encouraging therapeutic effects in patients treated with stem cells. Although there remain many unresolved issues, the available data support the notion that stem cell technology may lead to the development of effective clinical modalities for human liver diseases.
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65
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Hirose Y, Itoh T, Miyajima A. Hedgehog signal activation coordinates proliferation and differentiation of fetal liver progenitor cells. Exp Cell Res 2009; 315:2648-57. [PMID: 19559697 DOI: 10.1016/j.yexcr.2009.06.018] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2009] [Revised: 05/11/2009] [Accepted: 06/16/2009] [Indexed: 02/07/2023]
Abstract
Hedgehog (Hh) signaling plays crucial roles in development and homeostasis of various organs. In the adult liver, it regulates proliferation and/or viability of several types of cells, particularly under injured conditions, and is also implicated in stem/progenitor cell maintenance. However, the role of this signaling pathway during the normal developmental process of the liver remains elusive. Although Sonic hedgehog (Shh) is expressed in the ventral foregut endoderm from which the liver derives, the expression disappears at the onset of the liver bud formation, and its possible recurrence at the later stages has not been investigated. Here we analyzed the activation and functional relevance of Hh signaling during the mouse fetal liver development. At E11.5, Shh and an activation marker gene for Hh signaling, Gli1, were expressed in Dlk(+) hepatoblasts, the fetal liver progenitor cells, and the expression was rapidly decreased thereafter as the development proceeded. In the culture of Dlk(+) hepatoblasts isolated from the E11.5 liver, activation of Hh signaling stimulated their proliferation and this effect was cancelled by a chemical Hh signaling inhibitor, cyclopamine. In contrast, hepatocyte differentiation of Dlk(+) hepatoblasts in vitro as manifested by the marker gene expression and acquisition of ammonia clearance activity was significantly inhibited by forced activation of Hh signaling. Taken together, these results demonstrate the temporally restricted manner of Hh signal activation and its role in promoting the hepatoblast proliferation, and further suggest that the pathway needs to be shut off for the subsequent hepatic differentiation of hepatoblasts to proceed normally.
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Affiliation(s)
- Yoshikazu Hirose
- Laboratory of Cell Growth and Differentiation, Institute of Molecular and Cellular Biosciences, The University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo, Japan
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66
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Zong Y, Panikkar A, Xu J, Antoniou A, Raynaud P, Lemaigre F, Stanger BZ. Notch signaling controls liver development by regulating biliary differentiation. Development 2009; 136:1727-39. [PMID: 19369401 DOI: 10.1242/dev.029140] [Citation(s) in RCA: 333] [Impact Index Per Article: 22.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
In the mammalian liver, bile is transported to the intestine through an intricate network of bile ducts. Notch signaling is required for normal duct formation, but its mode of action has been unclear. Here, we show in mice that bile ducts arise through a novel mechanism of tubulogenesis involving sequential radial differentiation. Notch signaling is activated in a subset of liver progenitor cells fated to become ductal cells, and pathway activation is necessary for biliary fate. Notch signals are also required for bile duct morphogenesis, and activation of Notch signaling in the hepatic lobule promotes ectopic biliary differentiation and tubule formation in a dose-dependent manner. Remarkably, activation of Notch signaling in postnatal hepatocytes causes them to adopt a biliary fate through a process of reprogramming that recapitulates normal bile duct development. These results reconcile previous conflicting reports about the role of Notch during liver development and suggest that Notch acts by coordinating biliary differentiation and morphogenesis.
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Affiliation(s)
- Yiwei Zong
- Abramson Family Cancer Research Institute, University of Pennsylvania School of Medicine, Philadelphia, PA 19104, USA
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67
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Tanimizu N, Miyajima A, Mostov KE. Liver progenitor cells fold up a cell monolayer into a double-layered structure during tubular morphogenesis. Mol Biol Cell 2009; 20:2486-94. [PMID: 19297530 DOI: 10.1091/mbc.e08-02-0177] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
Bile ducts are hepatic tubular structures that are lined by cholangiocytes, a type of liver epithelial cell. Cholangiocytes first form a single layer of cells, termed the ductal plate, surrounding the portal vein, which eventually remodels into the branching tubular network of bile ducts. The process of bile duct morphogenesis is not yet clear: a conventional model where cholangiocytes proliferate to duplicate a single layer of the ductal plate before lumen formation seems inconsistent with the observation that proliferation is dramatically reduced when hepatoblasts, liver progenitor cells, differentiate into cholangiocytes. Here, we developed a new culture system in which a liver progenitor cell line, HPPL, reorganizes from a monolayer to tubular structures in response to being overlaid with a gel containing type I collagen and Matrigel. We found that some of the HPPL in the monolayer depolarized and migrated to fold up the monolayer into a double-cell layer. These morphogenetic processes occurred without cell proliferation and required phosphatidylinositol 3-kinase and Akt activity. Later in morphogenesis, luminal space was generated between the two cell layers. This process, in particular enlargement of the apical lumen, involved transcriptional activity of HNF1beta. Thus, using this sandwich culture system, we could segregate tubulogenesis of bile ducts into distinct steps and found that the PI3K/Akt pathway and HNF1beta regulated different steps of the morphogenesis. Although the process of tubulogenesis in culture specifically resembled early bile duct formation, involvement of these two key players suggests that the sandwich culture might help us to find common principles of tubulogenesis in general.
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Affiliation(s)
- Naoki Tanimizu
- Departments of Anatomy, and Biochemistry and Biophysics, University of California San Francisco, San Francisco, CA 94143-2140, USA
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Oikawa T, Kamiya A, Kakinuma S, Zeniya M, Nishinakamura R, Tajiri H, Nakauchi H. Sall4 regulates cell fate decision in fetal hepatic stem/progenitor cells. Gastroenterology 2009; 136:1000-11. [PMID: 19185577 DOI: 10.1053/j.gastro.2008.11.018] [Citation(s) in RCA: 87] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/20/2008] [Revised: 10/20/2008] [Accepted: 11/06/2008] [Indexed: 12/17/2022]
Abstract
BACKGROUND & AIMS Fetal hepatic stem/progenitor cells, called hepatoblasts, differentiate into both hepatocytes and cholangiocytes. The molecular mechanisms regulating this lineage segmentation process remain unknown. Sall4 has been shown to be among the regulators of organogenesis, embryogenesis, maintenance of pluripotency, and early embryonic cell fate decisions in embryonic stem cells. The expression and functional roles of Sall4 during liver development have not been elucidated. We here provide their first description in hepatoblasts. METHODS To investigate functions of Sall4 in fetal liver development, Dlk(+)CD45(-)Ter119(-) hepatoblasts derived from embryonic day 14 mouse livers were purified, and in vitro gain and loss of function analyses and in vivo transplantation analyses were performed using retrovirus- or lentivirus-mediated gene transfer. RESULTS We demonstrated that Sall4 was expressed in fetal hepatoblasts but not adult hepatocytes. The expression level of Sall4 gradually fell during liver development. Overexpression of Sall4 in hepatoblasts significantly inhibited maturation induced by oncostatin M and extracellular matrix in vitro, as evidenced by morphologic changes and suppression of hepatic maturation marker gene expression. When bile duct-like structures were induced by collagen gel-embedded culture, overexpression of Sall4 markedly augmented size and number of cytokeratin19(+)-branching structures. Knockdown of Sall4 inhibited formation of these branching structures. With in vivo transplantation, Sall4 enhanced differentiation of cytokeratin19(+)-bile ducts derived from transplanted hepatoblasts. CONCLUSIONS These results suggest that Sall4 plays a crucial role in controlling the lineage commitment of hepatoblasts not only inhibiting their differentiation into hepatocytes but also driving their differentiation toward cholangiocytes.
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Affiliation(s)
- Tsunekazu Oikawa
- Division of Stem Cell Therapy, Center for Stem Cell and Regenerative Medicine, The Institute of Medical Science, University of Tokyo, Tokyo, Japan
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69
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Wauthier E, Schmelzer E, Turner W, Zhang L, LeCluyse E, Ruiz J, Turner R, Furth M, Kubota H, Lozoya O, Barbier C, McClelland R, Yao H, Moss N, Bruce A, Ludlow J, Reid L. Hepatic Stem Cells and Hepatoblasts: Identification, Isolation, and Ex Vivo Maintenance. Methods Cell Biol 2008; 86:137-225. [DOI: 10.1016/s0091-679x(08)00008-3] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
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70
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Tanimizu N, Miyajima A, Mostov KE. Liver progenitor cells develop cholangiocyte-type epithelial polarity in three-dimensional culture. Mol Biol Cell 2007; 18:1472-9. [PMID: 17314404 PMCID: PMC1838984 DOI: 10.1091/mbc.e06-09-0848] [Citation(s) in RCA: 142] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
Cholangiocytes are cellular components of the bile duct system of the liver, which originate from hepatoblasts during embryonic liver development. Although several transcription factors and signaling molecules have been implicated in bile duct development, its molecular mechanism has not been studied in detail. Here, we applied a three-dimensional (3D) culture technique to a liver progenitor cell line, HPPL, to establish an in vitro culture system in which HPPL acquire differentiated cholangiocyte characteristics. When HPPL were grown in a gel containing Matrigel, which contains extracellular matrix components of basement membrane, HPPL developed apicobasal polarity and formed cysts, which had luminal space inside. In the cysts, F-actin bundles and atypical protein kinase C were at the apical membrane, E-cadherin was localized at the lateral membrane, and beta-catenin and integrin alpha6 were located at the basolateral membrane. HPPL in cysts expressed cholangiocyte markers, including cytokeratin 19, integrin beta4, and aquaporin-1, but not a hepatocyte marker, albumin. Furthermore, HPPL transported rhodamine 123, a substrate for multidrug resistance gene products, from the basal side to the central lumen. These data indicate that HPPL develop cholangiocyte-type epithelial polarity in 3D culture. Phosphatidylinositol 3-kinase signaling was essential for proliferation and survival of HPPL in culture, whereas laminin-1 was a crucial component of Matrigel for inducing epithelial polarization of HPPL. Because HPPL cysts display structural and functional similarities with bile ducts, the 3D culture of HPPL recapitulates in vivo cholangiocyte differentiation and is useful to study the molecular mechanism of bile duct development in vitro.
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Affiliation(s)
- Naoki Tanimizu
- *Departments of Anatomy and Biochemistry and Biophysics, University of California San Francisco, San Francisco, CA 94143-2140; and
| | - Atsushi Miyajima
- Institute of Molecular and Cellular Biosciences, University of Tokyo, Tokyo 113-0032, Japan
| | - Keith E. Mostov
- *Departments of Anatomy and Biochemistry and Biophysics, University of California San Francisco, San Francisco, CA 94143-2140; and
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Abstract
The liver is the central organ for metabolism and has strong regenerative capability. Although the liver has been studied mostly biochemically and histopathologically, genetic studies using gene-targeting technology have identified a number of cytokines, intracellular signaling molecules, and transcription factors involved in liver development and regeneration. In addition, various in vitro systems such as fetal liver explant culture and primary culture of fetal liver cells have been established, and the combination of genetic and in vitro studies has accelerated investigation of liver development. Identification of the cell-surface molecules of liver progenitors has made it possible to identify and isolate liver progenitors, making the liver a unique model for stem cell biology. In this review, we summarize progresses in understanding liver development and regeneration.
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Affiliation(s)
- Naoki Tanimizu
- Department of Anatomy, University of California San Francisco, San Francisco, California 94143, USA
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72
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Banas A, Yamamoto Y, Teratani T, Ochiya T. Stem cell plasticity: Learning from hepatogenic differentiation strategies. Dev Dyn 2007; 236:3228-41. [PMID: 17907200 DOI: 10.1002/dvdy.21330] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
Many studies on stem cell plasticity are challenging the concept that stem cells contain an intrinsically predefined, unidirectional differentiation program. This means that the developmental fate of a stem cell is dependent on the general potential of the cell (pre-determined stem cell fate) as well as on microenvironmental cues, such as stimuli from growth factors (stem cell niche). Here, we reviewed reports that examined the hepatocyte differentiation ability of stem cells from two different sources: embryonic stem cells and adult stem cells. All of those stem cells revealed the ability to give rise to hepatocyte-like cells using different induction strategies. However, it is still not clear which of those stem cells would be the best source for hepatocyte replacement or which would be the best protocol. We herein present the current knowledge regarding available protocols and factors used in order to obtain functional hepatocytes from stem cells.
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Affiliation(s)
- Agnieszka Banas
- Section for Studies on Metastasis, National Cancer Center Research Institute, Tokyo, Japan
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