Takamichi Ishii

Effects of extracellular matrixes and growth factors on the hepatic differentiation of human embryonic stem cells.

Hepatocytes derived from human embryonic stem cells (hESCs) are a potential cell source for regenerative medicine. However, the definitive factors that are responsible for hepatic differentiation of hESCs remain unclear. We aimed to evaluate the effects of various extracellular matrixes and growth factors on endodermal differentiation and to optimize the culture conditions to induce hepatic differentiation of hESCs. The transgene vector that contained enhanced green fluorescent protein (EGFP) under the control of human alpha-fetoprotein (AFP) enhancer/promoter was transfected into hESC lines. The transgenic hESCs were cultured on extracellular matrixes (collagen type I, laminin, and Matrigel) in the presence or absence of growth factors including hepatocyte growth factor (HGF), bone morphogenetic protein 4, fibroblast growth factor 4, all-trans-retinoic acid, and activin A. The expression of AFP-EGFP was measured by flow cytometry. The culture on Matrigel-coated dishes with 100 ng/ml activin A showed 19.5% of EGFP-positive proportions. Moreover, the sequential addition of 100 ng/ml activin A and 20 ng/ml HGF resulted in 21.7% and produced a higher yield of EGFP-positive cells than the group stimulated by activin A alone. RT-PCR and immunocytochemical staining revealed these EGFP-positive cells to differentiate into mesendoderm-like cells by use of activin A and then into hepatic endoderm cells by use of HGF. Two other hESC lines also differentiated into endoderm on the hepatic lineage by our method. In conclusion, we therefore found this protocol to effectively differentiate multiple hESC lines to early hepatocytes using activin A and HGF on Matrigel.

Transplantation of Embryonic Stem Cell‐Derived Endodermal Cells into Mice with Induced Lethal Liver Damage

ESCs are a potential cell source for cell therapy. However, there is no evidence that cell transplantation using ESC‐derived hepatocytes is therapeutically effective. The main objective of this study was to assess the therapeutic efficacy of the transplantation of ESC‐derived endodermal cells into a liver injury model. The β‐galactosidase‐labeled mouse ESCs were differentiated into α‐fetoprotein (AFP)‐producing endodermal cells. AFP‐producing cells or ESCs were transplanted into transgenic mice that expressed diphtheria toxin (DT) receptors under the control of an albumin enhancer/promoter. Selective damage was induced in the recipient hepatocytes by the administration of DT. Although the transplanted AFP‐producing cells had repopulated only 3.4% of the total liver mass 7 days after cell transplantation, they replaced 32.8% of the liver by day 35. However, these engrafted cells decreased (18.3% at day 40 and 7.9% at day 50) after the cessation of DT administration, and few donor cells were observed by days 60–90. The survival rate of the AFP‐producing cell‐transplanted group (66.7%) was significantly higher in comparison with that of the sham‐operated group (17.6%). No tumors were detected by day 50 in the AFP‐producing cell‐transplanted group; however, splenic teratomas did form 60 days or more after transplantation. ESC transplantation had no effect on survival rates; furthermore, there was a high frequency of tumors in the ESC‐transplanted group 35 days after transplantation. In conclusion, this study demonstrates, for the first time, that ESC‐derived endodermal cells improve the survival rates after transplantation into mice with induced hepatocellular injury.

Keratin 19, a Cancer Stem Cell Marker in Human Hepatocellular Carcinoma

Purpose: Keratin 19 (K19) is a known marker of poor prognosis and invasion in human hepatocellular carcinoma (HCC). However, the relationship between K19 and cancer stem cells (CSCs) is unclear. Here, we determined whether K19 can be used as a new CSC marker and therapeutic target in HCC. Experimental Design: HCC cell lines were transfected with a K19 promoter–driven enhanced green fluorescence protein gene. CSC characteristics, epithelial–mesenchymal transition (EMT), and TGFb/Smad signaling were examined in FACS-isolated K19+/K19− cells. K19 and TGFb receptor 1 (TGFbR1) expression in 166 consecutive human HCC surgical specimens was examined immunohistochemically. Results: FACS-isolated single K19+ cells showed self-renewal and differentiation into K19− cells, whereas single K19− cells did not produce K19+ cells. K19+ cells displayed high proliferation capacity and 5-fluorouracil resistance in vitro. Xenotransplantation into immunodeficient mice revealed that K19+ cells reproduced, differentiated into K19− cells, and generated large tumors at a high frequency in vivo. K19+ cells were found to be involved in EMT and the activation of TGFb/Smad signaling, and these properties were suppressed by K19 knockdown or treatment with a TGFbR1 inhibitor. The TGFbR1 inhibitor also showed high therapeutic effect against K19+ tumor in the mouse xenograft model. Immunohistochemistry of HCC specimens showed that compared with K19− patients, K19+ patients had significantly poorer recurrence-free survival and higher tumor TGFbR1 expression. Conclusions: K19 is a new CSC marker associated with EMT and TGFb/Smad signaling, and it would thus be a good therapeutic target for TGFbR1 inhibition. Clin Cancer Res; 21(13); 3081–91. ©2015 AACR.

Alpha-fetoprotein producing cells act as cancer progenitor cells in human cholangiocarcinoma.

We aimed to demonstrate that alpha-fetoprotein (AFP)-producing cells in cholangiocarcinomas possessed cancer stem cell (CSC)-like properties. AFP enhancer/promoter-driven EGFP gene was transfected into human cholangiocarcinoma cell lines. One cell line, RBE, expressed both AFP and EGFP. Clonal analyses revealed that one EGFP-positive cell generated both EGFP-positive and EGFP-negative cell fractions. However, one EGFP-negative cell never produced EGFP-positive cells. The EGFP-positive cells had a greater tumorigenic potential. Only the EGFP-positive cells expressed Notch1. AFP and Notch1 expression was observed in clinical intrahepatic cholangiocarcinomas. The AFP-producing cells were suggested to be CSCs. The Notch pathway might play an important role in maintaining the CSC characteristics.

In vitro hepatic maturation of human embryonic stem cells by using a mesenchymal cell line derived from murine fetal livers

Hepatocytes derived from human embryonic stem cells (hESCs) are an attractive cell source for regenerative medicine. We previously reported the differentiation of hESCs into alpha-fetoprotein (AFP)-producing endodermal cells by using extracellular matrix and growth factors. We also reported the establishment of the MLSgt20 cell line, which was derived from mesenchymal cells residing in murine fetal livers and accelerated the hepatic maturation of both murine hepatic progenitor cells and murine ESCs. In this study, hESC-derived AFP-producing cells were isolated by using a flow cytometer and co-cultured with MLSgt20 cells. The co-cultured hESC-derived AFP-producing cells had the immunocytological characteristics of hepatocytes, expressed mature hepatocyte markers (as indicated by reverse transcription and the polymerase chain reaction), and displayed higher hepatocyte functions including ammonia removal, cytochrome P450 3A4/7 activity, and the ability to produce and store glycogen. However, the MLSgt20 cells did not directly cause undifferentiated hESCs to mature into hepatocyte-like cells. The co-culture method was thus successfully shown to induce the differentiation of hESC-derived endodermal cells into functional hepatocyte-like cells.

An eClinical trial system for cancer that integrates with clinical pathways and electronic medical records

Background Various information technologies currently are used to improve the efficiency of clinical trials. However, electronic medical records (EMRs) are not yet linked to the electronic data capture (EDC) system. Therefore, the data must be extracted from medical records and transcribed to the EDC system. Clinical pathways are planned process patterns that are used in routine clinical practice and are easily applicable to the medical care and evaluation defined in a trial protocol. However, few clinical pathways are intended to increase the efficiency of clinical trials. Purpose Our purpose is to describe the design and development of a new clinical trial process model that enables the primary use of EMRs in clinical trials by integrating clinical pathways and EMRs. Methods We designed a new clinical trial model that uses EMR data directly in clinical trials and developed a system to follow this model. We applied the system to an investigator-initiated clinical trial and examined whether all data were extracted correctly. At the protocol development stage, our model measures endpoints based on clinical pathways with the same diagnosis. Next, medical record descriptions and the format of the statistical data are defined. According to these observations, screens for entry of data, which are used both in clinical practice and for study, are prepared into EMRs with an EMR template, and screens are prepared for data checks on our EMR retrieval system (ERS). In an actual trial, patients are registered and randomly assigned to a protocol treatment. The protocol treatment is executed according to clinical pathways, and the data are recorded to EMRs using EMR templates. The data are checked by a local data manager using reports created by the ERS. After edit checks and corrections, the data are extracted by the ERS, archived in portable document format (PDF) with an electronic signature, and transferred in comma-separated values (CSV) format to a coordinating centre. At the coordinating centre, the data are checked, integrated, and made available for a statistical analysis. Results We verified that the data could be extracted correctly and found no unexpected problems. Limitation To execute clinical trials in our system, the EMR template and efficient ERSs are required. Additionally, to execute multi-institutional clinical trials, it is necessary to create templates appropriate for EMRs at all participating sites and for the coordinating centre to validate local templates and procedures. Conclusion We proposed and pilot tested a new eClinical trial model. Because our model is integrated with routine documentation of clinical practice and clinical trials, redundant data entries were avoided and the burden on the investigator was minimised. The reengineering of the clinical trial process would facilitate the establishment of evidence in the future.

SOX9 is a novel cancer stem cell marker surrogated by osteopontin in human hepatocellular carcinoma.

The current lack of cancer stem cell (CSC) markers that are easily evaluated by blood samples prevents the establishment of new therapeutic strategies in hepatocellular carcinoma (HCC). Herein, we examined whether sex determining region Y-box 9 (SOX9) represents a new CSC marker, and whether osteopontin (OPN) can be used as a surrogate marker of SOX9 in HCC. In HCC cell lines transfected with a SOX9 promoter-driven enhanced green fluorescence protein gene, FACS-isolated SOX9+ cells were capable of self-renewal and differentiation into SOX9− cells, and displayed high proliferation capacity in vitro. Xenotransplantation experiments revealed that SOX9+ cells reproduced, differentiated into SOX9− cells, and generated tumors at a high frequency in vivo. Moreover, SOX9+ cells were found to be involved in epithelial-mesenchymal transition (EMT) and activation of TGFb/Smad signaling. Gain/loss of function experiments showed that SOX9 regulates Wnt/beta-catenin signaling, including cyclin D1 and OPN. Immunohistochemistry of 166 HCC surgical specimens and serum OPN measurements showed that compared to SOX9− patients, SOX9+ patients had significantly poorer recurrence-free survival, stronger venous invasion, and higher serum OPN levels. In conclusion, SOX9 is a novel HCC-CSC marker regulating the Wnt/beta-catenin pathway and its downstream target, OPN. OPN is a useful surrogate marker of SOX9 in HCC.

Alpha-fetoprotein-producing pancreatic cancer cells possess cancer stem cell characteristics

We aimed to demonstrate the existence of cancer stem cells in human pancreatic cancer, and to clarify that they are alpha-fetoprotein (AFP) producing cells. Six cell lines derived from human pancreatic cancers were examined, and AsPC-1 and PANC-1 were noted to express AFP. Single cell culture assays and xenotransplantation revealed that the AFP-producing cells had the capacity for self-renewal and differentiation, and that these cells were tumorigenic. Furthermore, they were resistant to anti-cancer agents. The ABCA12 transporter was expressed in the AFP-producing cells at a level more than twice as high as that in the non-AFP-producing cells. The AFP-producing cells were shown to be putative pancreatic cancer stem cells. Furthermore, the expression of ABCA12 appears to be associated with drug resistance.

Improvement of the survival rate by fetal liver cell transplantation in a mice lethal liver failure model.

Background. The use of cell transplantation as an alternative therapy for orthotopic liver transplantation has been widely anticipated due to a chronic donor shortage. We previously reported the method used to enrich hepatic progenitor cells (HPCs) forming cell aggregations. In this study, we transplanted HPCs into the liver injury model mice to determine whether HPC transplantation may improve the liver dysfunction. Methods. We obtained donor cells from E13.5 fetal livers of green fluorescent protein (GFP) transgenic mice. We transplanted GFP-positive fetal liver cells into the transgenic mice which express diphtheria toxin (DT) receptors under the control of an albumin enhancer/promoter. Subsequently, we induced selective liver injury to recipient mice by DT administration. We then evaluated the engraftment of the transplanted cells and their effect on survivorship. Results. The low dose of DT induced sublethal liver injury and the high dose of DT was lethal to the liver injury model mice. The transplanted GFP-positive cells were engrafted into the recipient livers and expressed albumin, resembling mature hepatocytes. They continued to proliferate, forming clusters. The survival rate at 25 days after transplantation of the cell-transplanted group (8 of 20; 40.0%) was improved significantly (P=0.0047) in comparison to that of the sham-operated group (0 of 20; 0%). Conclusions. The transplanted cells were engrafted and repopulated the liver of recipient mice, resulting in the improvement of the survival rate of the liver injury model mice. We therefore propose that HPCs are a desirable cell source for cell transplantation.

Hepatic Differentiation of Embryonic Stem Cells by Murine Fetal Liver Mesenchymal Cells

Hepatocytes derived from embryonic stem cells (ESCs) are a potential cell source for regenerative medicine. However, it has been technically difficult to differentiate ESCs into mature hepatocytes because the definitive growth factors and molecular mechanisms governing hepatocyte differentiation have not yet been well defined. The CD45(-)CD49f(+/-)Thy1(+)gp38(+) mesenchymal cells that reside in murine fetal livers induce hepatic progenitor cells to differentiate into mature hepatocytes by direct cell-cell contact. Utilizing these cells, we employ a two-step procedure for hepatic maturation of ESCs: first, ESCs are differentiated into endodermal cells or hepatic progenitor cells, and second, ESC-derived endodermal cells are matured into functional hepatocytes by coculture with murine fetal liver mesenchymal cells. The ESC-derived hepatocyte-like cells possess hepatic functions, including ammonia removal activity, albumin secretion ability, glycogen synthesis and storage, and cytochrome P450 enzymatic activity.