Differentiation of Mouse Hepatic Progenitor Cells Induced by Hepatocyte Nuclear Factor-4 and Cell Transplantation in Mice With Liver Fibrosis

Therapeutic effect of hepatocyte growth factor-overexpressing bone marrow-derived mesenchymal stem cells on CCl4-induced hepatocirrhosis

Hepatocirrhosis is one of the most severe complications of chronic hepatic disease in terms of medical intervention, and the available therapies are limited and not very successful. In this study, bone marrow-derived mesenchymal stem cells (BM-MSCs) from host rats were transduced with an adenoviral vector labelled with green fluorescent protein (EGFP) to overexpress hepatocyte growth factor (HGF). The therapeutic effect of these modified stem cells (HGF-BM-MSC group) transplanted intravenously into hepatocirrhosis model rats treated with CCl₄ was evaluated using serological, biochemical and histological approaches. We compared the rats in the HGF-BM-MSC group with those in the other groups (rats treated with BM-MSCs, rats treated with HGF and untreated rats (Controls)) in detail. The localisation of EGFP-tagged BM-MSCs in the injured liver was evaluated using a microscope, and the cells co-expressed hepatocyte nuclear factor 4α, albumin and cytokeratin 18. After treatment for 4 weeks, the HGF-BM-MSC, BM-MSC and HGF groups exhibited increased protein and mRNA levels of hepatocyte nuclear factor 4α, albumin and cytokeratin 18, but decreased levels of aspartate aminotransferase, alanine aminotransferase and total bilirubin. These findings indicate that BM-MSC transplantation and HGF application have great potential for the treatment of hepatocirrhosis.

Impact of Three-Dimentional Culture Systems on Hepatic Differentiation of Puripotent Stem Cells and Beyond

Generation of functional hepatocytes from human pluripotent stem cells (hPSCs) is a vital tool to produce large amounts of human hepatocytes, which hold a great promise for biomedical and regenerative medicine applications. Despite a tremendous progress in developing the differentiation protocols recapitulating the developmental signalling and stages, these resulting hepatocytes from hPSCs yet achieve maturation and functionality comparable to those primary hepatocytes. The absence of 3D milieu in the culture and differentiation of these hepatocytes may account for this, at least partly, thus developing an optimal 3D culture could be a step forward to achieve this aim. Hence, review focuses on current development of 3D culture systems for hepatic differentiation and maturation and the future perspectives of its application.

Efficient generation of functional hepatocyte-like cells from mouse liver progenitor cells via indirect co-culture with immortalized human hepatic stellate cells

BACKGROUND

Differentiation of liver progenitor cells (LPCs) to functional hepatocytes holds great potential to develop new strategies for hepatocyte transplantation and the screening of drug-induced cytotoxicity. However, reports on the efficient and convenient hepatic differentiation of LPCs to hepatocytes are few. The present study aims to investigate the possibility of generating functional hepatocytes from LPCs in an indirect co-culture system.

METHODS

Mouse LPCs were co-cultured in Transwell plates with an immortalized human hepatic stellate cell line (HSC-Li) we previously established. The morphology, expression of hepatic markers, and functions of mouse LPC-derived cells were monitored and compared with those of conventionally cultured LPCs.

RESULTS

Co-culturing with HSC-Li cells induced differentiation of mouse LPCs into functional hepatocyte-like cells. The differentiated cells were morphologically transformed into hepatocyte-like cells 3 days after co-culture initiation. In addition, the differentiated cells expressed liver-specific genes and possessed hepatic functions, including glycogen storage, low-density lipoprotein uptake, albumin secretion, urea synthesis, and cytochrome P450 1A2 enzymatic activity.

CONCLUSIONS

Our method, which employs indirect co-culture with HSC-Li cells, can efficiently induce the differentiation of LPCs into functional hepatocytes. This finding suggests that this co-culture system can be a useful method for the efficient generation of functional hepatocytes from LPCs.

Prolonged survival by combined treatment with granulocyte colony-stimulating factor and dipeptidyl peptidase IV inhibitor in a rat small-for-size liver transplantation model

AIM

Despite the great advances and excellent outcomes of liver transplantation (LT), small-for-size (SFS) graft syndrome is a life-threatening complication that remains to be overcome. In the present study, we investigated the therapeutic effect of combined treatment with granulocyte colony-stimulating factor (G-CSF) and a dipeptidyl peptidase IV (DPP-IV) inhibitor on SFS liver graft syndrome.

METHODS

The transplantation of small-sized Lewis donor livers into green fluorescent protein (GFP) transgenic Wistar rats was performed and the recipients were randomly assigned to one of four groups (without treatment, DPP-IV inhibitor treatment, G-CSF treatment and G-CSF/DPP-IV inhibitor combination). Recombinant human G-CSF was injected s.c. at a dose of 2 μg/kg per day starting 5 days prior to transplantation. G-CSF was combined with the p.o. administration of a DPP-IV inhibitor (2 mg/kg per day) after transplantation until the end of the observation period.

RESULTS

The post-transplant survival and liver function of rats treated with G-CSF/DPP-IV inhibitor combination therapy were significantly improved with an increased number of recipient-derived GFP positive cells into the liver grafts. A confocal microscopy study showed cytokeratin (CK)-18 and GFP positive hepatic progenitor cells in the parenchyma of the liver allografts. Untreated rats and rats treated with either G-CSF or DPP-IV inhibitor did not exhibit the prolonged survival and had less GFP and CK-18 positive cells in the liver grafts after SFS LT.

CONCLUSION

Our results suggest that combined treatment with G-CSF and DPP-IV inhibitor may synergistically induce migration and differentiation of recipient-derived stem cells into the hepatic progenitor cells, resulting in the amelioration of SFS liver graft syndrome.

Unbalanced distribution of materials: the art of giving rise to hepatocytes from liver stem/progenitor cells

Liver stem/progenitor cells (LSPCs) are able to duplicate themselves and differentiate into each type of cells in the liver, including mature hepatocytes and cholangiocytes. Understanding how to accurately control the hepatic differentiation of LSPCs is a challenge in many fields from preclinical to clinical treatments. This review summarizes the recent advances made to control the hepatic differentiation of LSPCs over the last few decades. The hepatic differentiation of LSPCs is a gradual process consisting of three main steps: initiation, progression and accomplishment. The unbalanced distribution of the affecting materials in each step results in the hepatic maturation of LSPCs. As the innovative and creative works for generating hepatocytes with full functions from LSPCs are gradually accumulated, LSPC therapies will soon be a new choice for treating liver diseases.

Efficient generation of functional hepatocytes from human embryonic stem cells and induced pluripotent stem cells by HNF4α transduction

Hepatocyte-like cells from human embryonic stem cells (ESCs) and induced pluripotent stem cells (iPSCs) are expected to be a useful source of cells drug discovery. Although we recently reported that hepatic commitment is promoted by transduction of SOX17 and HEX into human ESC- and iPSC-derived cells, these hepatocyte-like cells were not sufficiently mature for drug screening. To promote hepatic maturation, we utilized transduction of the hepatocyte nuclear factor 4α (HNF4α) gene, which is known as a master regulator of liver-specific gene expression. Adenovirus vector-mediated overexpression of HNF4α in hepatoblasts induced by SOX17 and HEX transduction led to upregulation of epithelial and mature hepatic markers such as cytochrome P450 (CYP) enzymes, and promoted hepatic maturation by activating the mesenchymal-to-epithelial transition (MET). Thus HNF4α might play an important role in the hepatic differentiation from human ESC-derived hepatoblasts by activating the MET. Furthermore, the hepatocyte like-cells could catalyze the toxication of several compounds. Our method would be a valuable tool for the efficient generation of functional hepatocytes derived from human ESCs and iPSCs, and the hepatocyte-like cells could be used for predicting drug toxicity.

HNF-4α determines hepatic differentiation of human mesenchymal stem cells from bone marrow

AIM: To investigate the differentiation status and key factors to facilitate hepatic differentiation of human bone-marrow-derived mesenchymal stem cells (MSCs).

METHODS: Human MSCs derived from bone marrow were induced into hepatocyte-like cells following a previously published protocol. The differentiation status of the hepatocyte-like cells was compared with various human hepatoma cell lines. Overexpression of hepatocyte nuclear factor (HNF)-4α was mediated by adenovirus infection of these hepatocyte-like cells. The expression of interesting genes was then examined by either reverse transcription-polymerase chain reaction (RT-PCR) or real-time RT-PCR methods.

RESULTS: Our results demonstrated that the differentiation status of hepatocyte-like cells induced from human MSCs was relatively similar to poorly differentiated human hepatoma cell lines. Interestingly, the HNF-4 isoform in induced MSCs and poorly differentiated human hepatoma cell lines was identified as HNF-4γ instead of HNF-4α. Overexpression of HNF-4α in induced MSCs significantly enhanced the expression level of hepatic-specific genes, liver-enriched transcription factors, and cytochrome P450 (P450) genes.

CONCLUSION: Overexpression of HNF-4α improves the hepatic differentiation of human MSCs from bone marrow and is a simple way of providing better cell sources for clinical applications.

Hepatic progenitor cells

Liver diseases are associated with a marked reduction in the viable mass of hepatocytes. The most severe cases of liver disease (liver failure) are treated by orthotopic liver transplantation. One alternative to whole organ transplantation for patients with hepatic failure (and hereditary liver disease) is hepatocyte transplantation. However, there is a serious limitation to the treatment of liver diseases either by whole organ or hepatocyte transplantation, and that is the shortage of organ donors. Therefore, to overcome the problem of organ shortage, additional sources of hepatocytes must be found. Alternative sources of cells for transplantation have been proposed including embryonic stem cells, immortalised liver cells and differentiated cells. One other source of cells for transplantation found in the adult liver is the progeny of stem cells. These cells are termed hepatic progenitor cells (HPCs). The therapeutic potential of HPCs lies in their ability to proliferate and differentiate into hepatocytes and cholangiocytes. However, using HPCs as a cell therapy cannot be exploited fully until the mechanisms governing hepatocyte differentiation are elucidated. Here, we discuss the fundamental cellular and molecular elements required for HPC differentiation to hepatocytes.