In vitro differentiation of embryonic stem cells into hepatocyte-like cells identified by cellular uptake of indocyanine green

Differentiation of Human Parthenogenetic Embryonic Stem Cells into Functional Hepatocyte-like Cells

Stem cell and tissue engineering-based therapies for acute liver failure (ALF) have been limited by the lack of an optimal cell source. We aimed to determine the suitability of human parthenogenetic embryonic stem cells (hPESCs) for the development of strategies to treat ALF. We studied the ability of human parthenogenetic embryonic stem cells (hPESCs) with high whole-genome SNP homozygosity, which were obtained by natural activation during in vitro fertilization (IVF), to differentiate into functional hepatocyte-like cells in vitro by monolayer plane orientation. hPESCs were induced on a single-layer flat plate for 21 d in complete medium with the inducers activin A, FGF-4, BMP-2, HGF, OSM, DEX, and B27. Polygonal cell morphology and binuclear cells were observed after 21 d of induction by using an inverted microscope. RT-qPCR results showed that the levels of hepatocyte-specific genes such as AFP, ALB, HNF4a, CYP3A4, SLCO1B3, and ABCC2 significantly increased after induction. Immunocytochemical assay showed CK18 and Hepa expression in the induced cells. Indocyanine green (ICG) staining showed that the cells had the ability to absorb and metabolize dyes. Detection of marker proteins and urea in cell culture supernatants showed that the cells obtained after 21 d of induction had synthetic and secretory functions. The typical ultrastructure of liver cells was observed using TEM after 21 d of induction. The results indicate that naturally activated hPESCs can be induced to differentiate into hepatocellular cells by monolayer planar induction.

Scaffold for liver tissue engineering: Exploring the potential of fibrin incorporated alginate dialdehyde-gelatin hydrogel

INTRODUCTION

Development of a tissue-engineered construct for hepatic regeneration remains a challenging task due to the lack of an optimum environment that support the growth of hepatocytes. Hydrogel systems possess many similarities with tissues and have the potential to provide the microenvironment essential for the cells to grow, proliferate, and remain functionally active.

METHODS

In this work, fibrin (FIB) incorporated injectable alginate dialdehyde (ADA) - gelatin (G) hydrogel was explored as a matrix for liver tissue engineering. ADA was prepared by periodate oxidation of sodium alginate. An injectable formulation of ADA-G-FIB hydrogel was prepared and characterized by FTIR spectroscopy, Scanning Electron Microscopy, and Micro-Computed Tomography. HepG2 cells were cultured on the hydrogel system; cellular growth and functions were analyzed using various functional markers.

RESULTS

FTIR spectra of ADA-G-FIB depicted the formation of Schiff's base at 1608.53 cm^-1 with a gelation time of 3 min. ADA-G-FIB depicted a 3D surface topography with a pore size in the range of 100-200 μm. The non-cytotoxic nature of the scaffold was demonstrated using L929 cells and more than 80 % cell viability was observed. Functional analysis of cultured HepG2 cells demonstrated ICG uptake, albumin synthesis, CYP-P450 expression, and ammonia clearance.

CONCLUSION

ADA-G-FIB hydrogel can be used as an effective 3D scaffold system for liver tissue engineering.

Down-regulation of SOX17, GATA4 and FoxA2 promotes differentiation potential of hepatocytes from human hematopoietic stem cells

The failure of regeneration of damaged liver in various end-stage liver diseases results in high morbidity and mortality. In this context, we have demonstrated the differentiation ability of human hematopoietic stem cells (HSCs) into hepatocytes. In this study, HSCs were isolated from a donor and cultured which exhibited the presence of CD34 and CD133 and absence of CD90 and CD73 markers. These CD34⁺ HSCs were induced for 21 days in hepatocyte differentiation medium (HDM). The obtained cells were characterized by immunocytochemical, immunofluorescence, western blot, qRT-PCR and flow cytometry analysis. Further, functional assays were done to accentuate the differentiated cells are hepatocytes. In HDM at day 6 differentiated cells showed the expression of definitive endodermal (DE) markers, SOX17, GATA4 and FoxA2 indicating the beginning of differentiation process. At day 21 the flow cytometry analysis showed 84.2 % positive to ALB-PE, 75.4 % positive to HNF4α-PE, and 77.3% positive to AFP-PE. Further, the qRT-PCR and western blot analysis presented prominent expression of hepatocyte-specific genes AAT, ALB, AFP, CK18, CK19, HNF4α, TFR2, and Hepcidin confirms the generation of hepatocytes in HDM. The ability of albumin secretion, urea production, glycogen storage, uptake of LDL, high ALDH enzyme activity describes the functionality of differentiated hepatocytes. Distinct expression of UGT1A1, CYP2B6, CYP2C9, CYP3A4, and CYP7A1 genes explains the ability to clear toxins and bilirubin as observed in normal hepatocytes. All these results indicate HSCs were differentiated into hepatocytes thus, autologous transplantation of HSCs could be a better option in the regeneration of the damaged liver.

Hepatic Differentiation of Marmoset Embryonic Stem Cells and Functional Characterization of ESC-Derived Hepatocyte-Like Cells

Background

Primary human hepatocytes (PHHs) are the ideal candidates for studying critical liver functions such as drug metabolism and toxicity. However, as they are isolated from discarded livers that are unsuitable for transplantation, they possess limited expansion ability in vitro and their enzymatic functions deteriorate rapidly because they are often of poor quality. Therefore, there is a compelling reason to find reliable alternative sources of hepatocytes.

Methods

In this study, we report on efficient and robust differentiation of embryonic stem cells (ESC) from the common marmoset Callithrix jacchus into functional hepatocyte-like cells (HLC) using a simple, and reproducible three-step procedure. ESC-derived HLCs were examined by morphological analysis and tested for their expression of hepatocyte-specific markers using a combination of immunohistochemistry, RT-PCR, and biochemical assays. Primary human hepatocytes were used as controls.

Results

ESC-derived HLCs expressed each of the hepatocyte-specific markers tested, including albumin; α-fetoprotein; asialoglycoprotein receptor 1; α-1 antitrypsin; hepatocyte nuclear factors 1α and 4; cytokeratin 18; hepatocyte growth factor receptor; transferrin; tyrosine aminotransferase; alkaline phosphatase; c-reactive protein; cytochrome P450 enzymes CYP1A2, CYP2E1 and CYP3A4; and coagulation factors FVII and FIX. They were functionally competent as demonstrated by biochemical assays in addition to producing urea.

Conclusion

Our data strongly suggest that marmoset HLCs possess characteristics similar to those of PHHs. They could, therefore, be invaluable for studies on drug metabolism and cell transplantation therapy for a variety of liver disorders. Because of the similarities in the anatomical and physiological features of the common marmoset to that of humans, Callithrix jacchus is an appropriate animal model to study human disease conditions and cellular functions.

Bimodal Molecule as NIR-CT Contrast Agent for Hepatoma Specific Imaging

With currently available molecular imaging techniques, hepatocellular carcinoma (HCC), a liver cancer with high mortality rates and poor treatment responses, is mostly diagnosed at its late stage. This is largely due to the lack of highly sensitive contrast agents with high liver specificity. Herein, we report a novel bimodal contrast agent molecule CNCI-1 for the effective detection of HCC at its early stage both in vitro and in vivo. The agent has high liver specificity with effective X-ray computed tomography (CT)/near-infrared (NIR) imaging functions. It has been successfully applied to in vivo NIR imaging with high sensitivity and high selectivity to the HCC region of the HepG2 tumor-xenografted mice model and LM3 orthotopic hepatoma mice model. Moreover, the agent was found to be noninvasive and hepatocarcinoma cells preferential. Furthermore, it also enhanced the tumor imaging by revealing the blood vessels nearby for the CT image acquisition in the VX2 orthotopic hepatoma rabbit model. Our design strategy provides a new avenue to develop the medical relevant bimodal contrast agents for diagnosis of HCC at its early stage.

Generation of functional hepatocyte-like cells from human bone marrow mesenchymal stem cells by overexpression of transcription factor HNF4α and FOXA2

BACKGROUND

Our previous study showed that overexpression of hepatocyte nuclear factor 4α (HNF4α) could directly promote mesenchymal stem cells (MSCs) to differentiate into hepatocyte-like cells. However, the efficiency of hepatic differentiation remains low. The purpose of our study was to establish an MSC cell line that overexpressed HNF4α and FOXA2 genes to obtain an increased hepatic differentiation efficiency and hepatocyte-like cells with more mature hepatocyte functions.

METHODS

Successful establishment of high-level HNF4α and FOXA2 co-overexpression in human induced hepatocyte-like cells (hiHep cells) was verified by flow cytometry, immunofluorescence and RT-PCR. Measurements of albumin (ALB), urea, glucose, indocyanine green (ICG) uptake and release, cytochrome P450 (CYP) activity and gene expression were used to analyze mature hepatic functions of hiHep cells.

RESULTS

hiHep cells efficiently express HNF4α and FOXA2 genes and proteins, exhibit typical epithelial morphology and acquire mature hepatocyte-like cell functions, including ALB secretion, urea production, ICG uptake and release, and glycogen storage. hiHep cells can be activated by CYP inducers. The percentage of both ALB and α-1-antitrypsin (AAT)-positive cells was approximately 72.6%. The expression levels of hepatocyte-specific genes (ALB, AAT, and CYP1A1) and liver drug transport-related genes (ABCB1, ABCG2, and SLC22A18) in hiHep cells were significantly higher than those in MSCs-Vector cells. The hiHep cells did not form tumors after subcutaneous xenograft in BALB/c nude mice after 2 months.

CONCLUSION

This study provides an accessible, feasible and efficient strategy to generate hiHep cells from MSCs.

Conversion of hepatoma cells to hepatocyte-like cells by defined hepatocyte nuclear factors

Normal cells become cancer cells after a malignant transformation, but whether cancer cells can be reversed to normal status remains elusive. Here, we report that the combination of hepatocyte nuclear factor 1A (HNF1A), HNF4A and forkhead box protein A3 (FOXA3) synergistically reprograms hepatocellular carcinoma (HCC) cells to hepatocyte-like cells (reprogrammed hepatocytes, rHeps). Our results show that rHeps lose the malignant phenotypes of cancer cells and retrieve hepatocyte-specific characteristics including hepatocyte-like morphology; global expression pattern of genes and specific biomarkers of hepatocytes; and the unique hepatic functions of albumin (ALB) secretion, glycogen synthesis, low-density lipoprotein (LDL) uptake, urea production, cytochrome P450 enzymes induction and drug metabolism. Intratumoral injection of these three factors efficiently shrank patient-derived tumor xenografts and reprogrammed HCC cells in vivo. Most importantly, transplantation of rHeps in the liver of fumarylacetoacetate hydrolase-deficient (Fah^-/-) mice led to the reconstruction of hepatic lobules and the restoration of hepatic function. Mechanistically, exogenous expression of HNF1A, HNF4A and FOXA3 in HCC cells initiated the endogenous expression of numerous hepatocyte nuclear factors, which promoted the conversion of HCC cells to hepatocyte-like cells. Collectively, our results indicate the successful conversion of hepatoma cells to hepatocyte-like cells, not only extending our current knowledge of cell reprogramming but also providing a route towards a novel therapeutic strategy for cancer.

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.

[Changes in autophagy during maturation and differentiation of Hepa1-6 cells induced by all-trans retinoic acid]

OBJECTIVE

To investigate the effects of different concentrations of all-trans retinoic acid (ATRA) on the maturation, differentiation and autophagy of Hepa1-6 cells.

MONTHOD

Hepa1-6 cells were treated with 0.1, 1, and 10 µmol/L ATRA, and the changes in the expressions of hepatic specific markers were detected using real-time PCR and Western blotting. Indocyanine green (ICG) and periodic acid-schiff (PAS) staining was used to assess the functional maturation of Hepa1-6 cells, and the cell-cell junction and autophagy were observed under transmission electron microscopy to determine the optimal concentration of ATRA for treatment. The expressions of autophagy-related markers in the cells were detected using Western blotting, and confocal microscopy was used to observe the autophagic flow in the cells transfected with ptfLC3 plasmid.

RESULTS

Compared with the control cells, the hepatocytes treated with ATRA showed a concentration-dependent decrease in AFP expression and increase in the expressions of ALB, CK18, TAT and ApoB. ICG and PAS staining revealed significantly increased number of positive cells after ATRA treatment. Following ATRA treatment, the cells exhibited obviously increased tight junctions, cytoskeleton and number of autophagosomes under transmission electron microscopy. ATRA treatment resulted in significantly increased the expressions of autophagy-related markers LC3-II, Beclin-1, RAB7 and P62 and also an increased ratio of LC3-II/LC3-I(P<0.05). Confocal microscopy revealed obviously increased green and red spots in the cells after ATRA treatment.

CONCLUSION

ATRA can induce the maturation and differentiation and enhance the level of autophagy in Hepa1-6 cells.

Hepatogenic Supported Differentiation of Mesenchymal Stem Cells in a Lactobionic Acid-Conjugated Thermogel

To investigate the effect of receptor substrate of target cells on stem cell differentiation, lactobionic acid-conjugated poly[(propylene glycol)-b-(ethylene glycol)-b-(propylene glycol)]-poly(l-alanine) (LB-PLX-PA) was synthesized, and then thermogelling systems consisting of LB-PLX-PA and PLX-PA in a ratio of 0/100 (LB-0), 5/95 (LB-5), and 20/80 (LB-20) were constructed as an injectable three-dimensional scaffold toward hepatogenic differentiation of tonsil-derived mesenchymal stem cells (TMSCs). Modulus of LB-0, LB-5, and LB-20 increased to 500-800 Pa at 37 °C (gel) due to the heat induced sol-to-gel transition of the systems during which TMSCs were incorporated into the gel. Based on biomarker expressions and hepatic biofunctions of the differentiated cells, the receptor substrate (LB)-conjugated bioactive thermogel provides compatible microenvironments for the differentiated cells, and thus gives pronounced positive results on the differentiation of the stem cells into target cells during three-dimensional culture, compared with a passive thermogel.

Differentiation Potential of Breast Milk-Derived Mesenchymal Stem Cells into Hepatocyte-Like Cells

Human breast milk stem cells (hBSCs) contain a population of cells with the ability to differentiate into various cell lineages for cell therapy applications. The current study examined the differentiation potential of hBSCs into hepatocytes-like cells. The cells were isolated from the breast milk and were treated with hepatogenic medium containing hepatocyte growth factor, insulin-like growth factor and dexamethasone for 7 days subsequently; Oncostatin M was added to the culture media. RT-PCR and immunocytochemistry were performed to detect the hepatogenic markers. The glycogen storage and the ability of the cells to absorb and release indocynanin green were also tested. The data showed that most of the differentiated cells formed cell aggregates after the 30th day, with more cells accumulated to form spheroids. RT-PCR revealed the expression of the hepatic nuclear factor, albumin, cytokeratin 18 and 19, cytochrome P2B6, glucose-6-phospahtase and claudin. The functional assays also showed glycogen storage and omission of indicynine green. Our study demonstrated hBSCs are novel population that can differentiate into hepatocyte-like cells.

Differentiation of Human and Mouse Embryonic Stem Cells along a Hepatocyte Lineage

Embryonic stem (ES) cells may differentiate along a hepatocyte lineage; however, currently there are no reports of culture conditions yielding high levels of hepatocyte-specific gene expression in these cells. We investigated culture conditions for differentiating ES cells into hepatocyte-like cells in vitro. Various combinations of culture media, growth and differentiation factors, and substratum precoatings were evaluated, and it was determined that a combination of Iscove's modified Dulbecco's medium with 20% fetal bovine serum, human insulin, dexamethasone, and collagen type I precoating was optimal for directing mouse ES cells along a hepatocyte lineage. Treatment of mouse ES cell with the optimal condition led to prealbumin gene expression 20% as high, and albumin synthesis 7% as high, as in mouse liver. The optimal culture condition also induced albumin gene expression in differentiated human ES cells 1% as high as in normal human hepatocytes as shown by Western blot analysis, and cells were positive for human albumin by immunocyto-chemistry. In addition, our optimal condition led to high levels of albumin gene expression in primary mouse hepatocytes after 35 days of culture, levels 10-fold higher than with other hepatocyte differentiation media. In conclusion, our optimal condition directed both mouse and human ES cells along a hepatocyte lineage. This represents the initial step in establishing cell lines that can be employed in cell-based therapeutics in humans and for toxicology and pharmacology studies.

Long-Term Maintenance of Liver-Specific Functions in Cultured ES Cell-Derived Hepatocytes with Hyaluronan Sponge

This study investigated the three-dimensional culture of hepatocytes differentiated from mouse embryonic stem (ES) cells with a porous hyaluronan (HA) sponge support. Hepatocytes were immobilized within the pores of the support. Spheroids could be observed within the support, each containing between 20 and 50 hepatocytes. To examine the liver-specific functions of the hepatocytes in the culture, the levels of albumin secreted into the medium were analyzed. The secretion of albumin was stable over the course of 32 days, longer than that in both conventional monolayer and collagen sponge cultures. To elucidate further the liver-specific functions of hepatocytes embedded in the HA sponge, metabolic activities of the hepatocytes were examined for their ability to eliminate ammonia from culture media and the synthesis of urea nitrogen. While rates of ammonia removal and urea nitrogen synthesis were similar to those in both conventional monolayer and in collagen sponge cultures, these functions were maintained for longer duration in cells embedded in the HA sponge. These results demonstrate that the porous HA sponge is an effective support for the in vitro culture of ES-derived hepatocytes used for both basic and applied studies for cell transplantation.

Induced pluripotent stem cell technology: a decade of progress

Since the advent of induced pluripotent stem cell (iPSC) technology a decade ago, enormous progress has been made in stem cell biology and regenerative medicine. Human iPSCs have been widely used for disease modelling, drug discovery and cell therapy development. Novel pathological mechanisms have been elucidated, new drugs originating from iPSC screens are in the pipeline and the first clinical trial using human iPSC-derived products has been initiated. In particular, the combination of human iPSC technology with recent developments in gene editing and 3D organoids makes iPSC-based platforms even more powerful in each area of their application, including precision medicine. In this Review, we discuss the progress in applications of iPSC technology that are particularly relevant to drug discovery and regenerative medicine, and consider the remaining challenges and the emerging opportunities in the field.

Functional comparison of human embryonic stem cells and induced pluripotent stem cells as sources of hepatocyte-like cells

Pluripotent stem cells can differentiate into many cell types including mature hepatocytes, and can be used in the development of new drugs, treatment of diseases, and in basic research. In this study, we established a protocol leading to efficient hepatic differentiation, and compared the capacity to differentiate into the hepatocyte lineage of human embryonic stem cells (hESCs) and human induced pluripotent stem cells (hiPSCs). Optimal combinations of cytokines and growth factors were added to embryoid bodies produced by both types of cell. Differentiation of the cells was assessed with optical and electron microscopes, and hepatic-specific transcripts and proteins were detected by quantitative reverse transcription polymerase chain reaction and immunocytochemistry, respectively. Both types of embryoid body produced polygonal hepatocyte-like cells accompanied by time-dependent up regulation of genes for α-fetoprotein, albumin (ALB), asialoglycoprotein1, CK8, CK18, CK19, CYP1A2, and CYP3A4, which are expressed in fetal and adult hepatocytes. Both types of cell displayed functions characteristic of mature hepatocytes such as accumulation of glycogen, secretion of ALB, and uptake of indocyanine green. And these cells are transplanted into mouse model. Our findings indicate that hESCs and hiPSCs have similar abilities to differentiate into hepatocyte in vitro using the protocol developed here, and these cells are transplantable into damaged liver.

Electronic Supplementary Material

Supplementary material is available for this article at 10.1007/s13770-016-0094-y and is accessible for authorized users.

Describing the Stem Cell Potency: The Various Methods of Functional Assessment and In silico Diagnostics

Stem cells are defined by their capabilities to self-renew and give rise to various types of differentiated cells depending on their potency. They are classified as pluripotent, multipotent, and unipotent as demonstrated through their potential to generate the variety of cell lineages. While pluripotent stem cells may give rise to all types of cells in an organism, Multipotent and Unipotent stem cells remain restricted to the particular tissue or lineages. The potency of these stem cells can be defined by using a number of functional assays along with the evaluation of various molecular markers. These molecular markers include diagnosis of transcriptional, epigenetic, and metabolic states of stem cells. Many reports are defining the particular set of different functional assays, and molecular marker used to demonstrate the developmental states and functional capacities of stem cells. The careful evaluation of all these methods could help in generating standard identifying procedures/markers for them.

Overexpression of transcription factor Foxa2 and Hnf1α induced rat bone mesenchymal stem cells into hepatocytes

Hepatocytes differentiated from induced pluripotent stem cells and adult stem cells could be utilized as a tool for the study of liver diseases, screening for drug metabolism and hepatotoxicity. Thus further investigation of the method to efficiently generate hepatocytes is in great need. Bone Mesenchymal Stem Cells (BMSCs) were collected from rat femurs and tibias. FOXA2 and HNF1α genes were constructed into a lentiviral vector and introduced into BMSCs by a lentivirus-mediated overexpression system. Three weeks after the induction, the expressions of FOXA2 and HNF1α, and liver specific genes were analyzed, and hepatocyte-function related assays were performed. Overexpression of both FOXA2 and HNF1α induced the BMSCs to differentiate into hepatocyte-like cells (HLCs). Hepatocyte-specific gene and protein were detected by RT-PCR, Western Blot and Immunofluorescence. These HLCs also exerted some typical hepatocyte functions such as glycogen storage, indocyanine green absorption and lipid accumulation. The combination of FOXA2 and HNF1α can effectively induce BMSCs to differentiate into HLCs. This is a novel and efficient method to prepare HLCs within a short timeline.

Lasing in blood

Indocyanine green (ICG) is the only near-infrared dye approved by the U.S. Food and Drug Administration for clinical use. When injected in blood, ICG binds primarily to plasma proteins and lipoproteins, resulting in enhanced fluorescence. Recently, the optofluidic laser has emerged as a novel tool in bio-analysis. Laser emission has advantages over fluorescence in signal amplification, narrow linewidth, and strong intensity, leading to orders of magnitude increase in detection sensitivity and imaging contrast. Here we successfully demonstrate, to the best of our knowledge, the first ICG lasing in human serum and whole blood with the clinical ICG concentrations and the pump intensity far below the clinically permissible level. Furthermore, we systematically study ICG laser emission within each major serological component (albumins, globulins, and lipoproteins) and reveal the critical elements and conditions responsible for lasing. Our work marks a critical step toward eventual clinical and biomedical applications of optofluidic lasers using FDA approved fluorophores, which may complement or even supersede conventional fluorescence-based sensing and imaging.

Small-Molecule-Directed Hepatocyte-Like Cell Differentiation of Human Pluripotent Stem Cells

Hepatocyte-like cells (HLCs) generated in vitro from human pluripotent stem cells (hPSCs) provide an invaluable resource for basic research, regenerative medicine, drug screening, toxicology, and modeling of liver disease and development. This unit describes a small-molecule-driven protocol for in vitro differentiation of hPSCs into HLCs without the use of growth factors. hPSCs are coaxed through a developmentally relevant route via the primitive streak to definitive endoderm (DE) using the small molecule CHIR99021 (a Wnt agonist), replacing the conventional growth factors Wnt3A and activin A. The small-molecule-derived DE is then differentiated to hepatoblast-like cells in the presence of dimethyl sulfoxide. The resulting hepatoblasts are then differentiated to HLCs with N-hexanoic-Tyr, Ile-6 aminohexanoic amide (Dihexa, a hepatocyte growth factor agonist) and dexamethasone. The protocol provides an efficient and reproducible procedure for differentiation of hPSCs into HLCs utilizing small molecules. © 2016 by John Wiley & Sons, Inc.

Sustained Delivery Growth Factors with Polyethyleneimine-Modified Nanoparticles Promote Embryonic Stem Cells Differentiation and Liver Regeneration

Stem-cell-derived hepatocyte transplantation is considered as a potential method for the therapy of acute and chronic liver failure. However, the low efficiency of differentiation into mature and functional hepatocytes remains a major challenge for clinical applications. By using polyethyleneimine-modified silica nanoparticles, this study develops a system for sustained delivery of growth factors, leading to induce hepatocyte-like cells (iHeps) from mouse embryonic stem cells (mESCs) and improve the expression of endoderm and hepatocyte-specific genes and proteins significantly, thus producing a higher population of functional hepatocytes in vitro. When transplanted into liver-injured mice after four weeks, mESC-derived definitive endoderm cells treated with this delivery system show higher integration efficiency into the host liver, differentiated into iHeps in vivo and significantly restored the injured liver. Therefore, these findings reveal the multiple advantages of functionalized nanoparticles to serve as efficient delivery platforms to promote stem cell differentiation in the regenerative medicine.

Hepatocyte growth factor-induced differentiation of bone mesenchymal stem cells toward hepatocyte-like cells occurs through nuclear factor-kappa B signaling in vitro

Hepatocyte growth factor (HGF) is multifaceted cytokine that regulates proliferation, differentiation, morphology, and motility within numerous stem cells. More recently, HGF has been reported to induce the differentiation of bone mesenchymal stem cells (BMSCs) into mature hepatocytes, but the underlying biochemical and molecular signaling is largely unknown. We isolated BMSC from the bone marrow of rats, which were then cultured and exposed to HGF for 15 days. We subsequently assayed these cells for liver functionality and markers, and blocked NF-кB signaling at various stages of the pathway. The present results demonstrate that HGF induces the differentiation of BMSCs toward hepatocyte-like cells through the NF-кB signaling. More specifically, HGF upregulated the translocation of NF-кB to the nucleus.

Useful properties of undifferentiated mesenchymal stromal cells and adipose tissue as the source in liver-regenerative therapy studied in an animal model of severe acute fulminant hepatitis

BACKGROUND AIMS

End-stage liver diseases frequently require liver transplantation. Cell therapy could be an alternative. This study aimed to analyze whether undifferentiated mesenchymal stromal cells (U-MSCs) or MSC-derived hepatocyte-like cells (DHLCs) from adipose tissue (AT), umbilical cord blood (UCB) and bone marrow (BM) would better restore damaged liver.

METHODS

AT was obtained from lipo-aspiration, UCB from an Umbilical Cord Blood Bank and BM from a BM Transplantation Unit. AT (collagenase digestion), UCB and BM (Ficoll gradient) were cultured (Dulbecco's modified Eagle's medium, low glucose, FBS) for 3 days. Detached adherent cells, at passage 4, were characterized as MSCs. Genetic stability was investigated by means of telomerase enzyme activity and karyotype. Hepatocyte differentiation protocol was performed with the use of Dulbecco's modified Eagle's medium, hepatocyte growth factor, basic fibroblast growth factor and nicotinamide (7 days); maturation medium (oncostatin, dexamethasone, insulin, transferrin and selenium) was added at 36 days. Hepatogenesis analyses were performed by use of morphology and albumin, AF, tyrosine-aminotransferase and glutamine synthetase gene expression and quantitative reverse transcription-polymerase chain reaction on days 9, 18, 25 and 36. Functionality was assessed through glycogen storage detection, indocyanine green absorption and transplantation procedure. U-MSCs and DHLCs were injected 48 h after induced fulminant hepatitis (intraperitoneal injection of carbon tetrachloride) in SCID/BALB-c mice. Histopathologic analyses were performed on days 7 and 15. Human origin included albumin and CK19 human markers.

RESULTS

All MSCs differentiated into functional hepatocyte-like cells, stored glycogen and absorbed indocyanine green. AT-MSC DHLC gene expression was more consistent with a normal hepatogenic-differentiation profile. UCB-MSCs expanded weakly, impairing their use for the transplantation procedure. AT and BM U-MSCs and DHLCs regenerated liver injury equally. Regenerated hepatocytes exhibited human origin.

CONCLUSIONS

AT might be the source and U-MSCS the stem cells useful for liver-regenerative therapy.

All-trans retinoic acid inhibits proliferation, migration, invasion and induces differentiation of hepa1-6 cells through reversing EMT in vitro

Hepatocellular carcinoma (HCC) has the characristics of tumor invasiveness, frequent intrahepatic spread and extra hepatic metastases, which affects the therapy efficiency and prognosis. Epithelial-mesenchymal transition (EMT) is now recognized as a key process in tumor invasion, metastasis and the generation of cancer initiating cells. All-trans retinoic acid (ATRA) is currently used as a potential chemo-therapeutic or chemo-preventive agent because of its anti-proliferative, pro-apoptotic and antioxidant properties. This study investigated the effects of ATRA at different concentrations on the proliferation, migration, invasion, differentiation and functions of the mouse hepa1-6 hepatocarcinoma cell line and explored whether ATRA regulates EMT in the antitumor process. Trypan blue staining and colony formation assay were used to detect cell proliferation. Wound-healing assay and Transwell Matrigel assay were performed to examine migration. Invasion was assessed by using Transwell invasion assay. In the present study, ATRA significantly inhibited the cell growth, colony formation, migration, and invasion capability of hepa1-6 cells in a dose-dependent manner. Furthermore, ATRA at low concentration (0.1 µmol/l) could generate these influences. After treated in the ATRA medium, the expression of mature hepatic markers ALB (albumin), CK18 (cytokeratin 18), TAT (tyrosine aminotransferase), ApoB (apolipoprotein B) decreased and that of hepatocarcinoma marker AFP (α fetoprotein) increased. At day 7 after ATRA induction, hepa1-6 cells showed comparable indocyanine green (ICG) uptake and glycogen storage function to the blank control. The mRNA expression of mesenchymal markers N-cadherin, vimentin, snail and twist decreased, while expression of epithelial marker E-cadherin increased in hepa1-6 cells after treated with ATRA. Therefore, this study demonstrates that ATRA remarkably suppressed the proliferation, migration, invasion of hepa1-6 hepatocarcinoma cell line and effectively induced its differentiation and liver functions in vitro through the reversal of EMT. HCC may be more sensitive to ATRA than other cancers, suggesting the prospective usefulness of ATRA in the treatment of HCC.

Design of a Vitronectin-Based Recombinant Protein as a Defined Substrate for Differentiation of Human Pluripotent Stem Cells into Hepatocyte-Like Cells

Maintenance and differentiation of human pluripotent stem cells (hPSCs) usually requires culture on a substrate for cell adhesion. A commonly used substratum is Matrigel purified from Engelbreth—Holm—Swarm sarcoma cells, and consists of a complex mixture of extracellular matrix proteins, proteoglycans, and growth factors. Several studies have successfully induced differentiation of hepatocyte-like cells from hPSCs. However, most of these studies have used Matrigel as a cell adhesion substrate, which is not a defined culture condition. In an attempt to generate a substratum that supports undifferentiated properties and differentiation into hepatic lineage cells, we designed novel substrates consisting of vitronectin fragments fused to the IgG Fc domain. hPSCs adhered to these substrates via interactions between integrins and the RGD (Arg-Gly-Asp) motif, and the cells maintained their undifferentiated phenotypes. Using a previously established differentiation protocol, hPSCs were efficiently differentiated into mesendodermal and hepatic lineage cells on a vitronectin fragment-containing substrate. We found that full-length vitronectin did not support stable cell adhesion during the specification stage. Furthermore, the vitronectin fragment with the minimal RGD-containing domain was sufficient for differentiation of human induced pluripotent stem cells into hepatic lineage cells under completely defined conditions that facilitate the clinical application of cells differentiated from hPSCs.

A Convenient and Efficient Method to Enrich and Maintain Highly Proliferative Human Fetal Liver Stem Cells

Pluripotent human hepatic stem cells have broad research and clinical applications, which are, however, restricted by both limited resources and technical difficulties with respect to isolation of stem cells from the adult or fetal liver. In this study, we developed a convenient and efficient method involving a two-step in situ collagenase perfusion, gravity sedimentation, and Percoll density gradient centrifugation to enrich and maintain highly proliferative human fetal liver stem cells (hFLSCs). Using this method, the isolated hFLSCs entered into the exponential growth phase within 10 days and maintained sufficient proliferative activity to permit subculture for at least 20 passages without differentiation. Immunocytochemistry, immunofluorescence, and flow cytometry results showed that these cells expressed stem cell markers, such as c-kit, CD44, epithelial cell adhesion molecule (EpCAM), oval cell marker-6 (OV-6), epithelial marker cytokeratin 18 (CK18), biliary ductal marker CK19, and alpha-fetoprotein (AFP). Gene expression analysis showed that these cells had stable mRNA expression of c-Kit, EpCAM, neural cell adhesion molecule (NCAM), CK19, CK18, AFP, and claudin 3 (CLDN-3) throughout each passage while maintaining low levels of ALB, but with complete absence of cytochrome P450 3A4 (C3A4), phosphoenolpyruvate carboxykinase (PEPCK), telomeric repeat binding factor (TRF), and connexin 26 (CX26) expression. When grown in appropriate medium, these isolated liver stem cells could differentiate into hepatocytes, cholangiocytes, osteoblasts, adipocytes, or endothelial cells. Thus, we have demonstrated a more economical and efficient method to isolate hFLSCs than magnetic-activated cell sorting (MACS). This novel approach may provide an excellent tool to isolate highly proliferative hFLSCs for tissue engineering and regenerative therapies.

Cell therapy for liver diseases: current medicine and future promises

Liver diseases are a major health problem worldwide since they usually represent the main causes of death in most countries, causing excessive costs to public health systems. Nowadays, there are no efficient current therapies for most hepatic diseases and liver transplant is infrequent due to the availability of organs, cost and risk of transplant rejection. Therefore, alternative therapies for liver diseases have been developed, including cell-based therapies. Stem cells (SCs) are characterized by their self-renewing capacity, unlimited proliferation and differentiation under certain conditions into tissue- or organ-specific cells with special functions. Cell-based therapies for liver diseases have been successful in experimental models, showing anti-inflammatory, antifibrogenic and regenerative effects. Nowadays, clinical trials using SCs for liver pathologies are increasing in number, and those that have reached publication have achieved favorable effects, encouraging us to think that SCs will have a potential clinical use in a short time.

5-azacytidine promotes terminal differentiation of hepatic progenitor cells

5-azacytidine (5-azaC) is known to induce cardiomyocyte differentiation. However, its function in hepatocyte differentiation is unclear. The present study investigated the in vitro capability of 5-azaC to promote maturation and differentiation of mouse embryonic hepatic progenitor cells, with the aim of developing an approach for improving hepatic differentiation. Mouse embryonic hepatic progenitor cells (HP14.5 cells) were treated with 5-azaC at concentrations from 0 to 20 μmol/l, in addition to hepatocyte induction culture medium. Hepatocyte induction medium induces HP14.5 cell differentiation. 5-azaC may enhance the albumin promotor-driven Gaussia luciferase (ALB-GLuc) activity in induced HP14.5 cells. In the present study 2 μmol/l was found to be the optimum concentration with which to achieve this. The expression of hepatocyte-associated factors was not significantly different between the group treated with 5-azaC alone and the control group. The mRNA levels of ALB; cytokeratin 18 (CK18); tyrosine aminotransferase (TAT); and cytochrome p450, family 1, member A1 (CYP1A1); in addition to the protein levels of ALB, CK18 and uridine diphosphate glucuronyltransferase 1A (UGT1A) in the induced group with 5-azaC, were higher than those in the induced group without 5-azaC, although no significant differences were detected in expression of the hepatic stem cell markers, DLK and α-fetoprotein, between the two groups. Treatment with 5-azaC alone did not affect glycogen synthesis or indocyanine green (ICG) metabolic function in HP14.5 cells, although it significantly increased ICG uptake and periodic acid-Schiff-positive cell numbers amongst HP14.5 cells. Therefore, the present study demonstrated that treatment with 5-azaC alone exerted no effects on the maturation and differentiation of HP14.5 cells. However, 5-azaC exhibited a synergistic effect on the terminal differentiation of induced hepatic progenitor cells in association with a hepatic induction medium.

Efficient large-scale generation of functional hepatocytes from mouse embryonic stem cells grown in a rotating bioreactor with exogenous growth factors and hormones

Introduction

Embryonic stem (ES) cells are considered a potentially advantageous source of hepatocytes for both transplantation and the development of bioartificial livers. However, the efficient large-scale generation of functional hepatocytes from ES cells remains a major challenge, especially for those methods compatible with clinical applications.

Methods

In this study, we investigated whether a large number of functional hepatocytes can be differentiated from mouse ES (mES) cells using a simulated microgravity bioreactor. mES cells were cultured in a rotating bioreactor in the presence of exogenous growth factors and hormones to form embryoid bodies (EBs), which then differentiated into hepatocytes.

Results

During the rotating culture, most of the EB-derived cells gradually showed the histologic characteristics of normal hepatocytes. More specifically, the expression of hepatic genes and proteins was detected at a higher level in the differentiated cells from the bioreactor culture than in cells from a static culture. On further growing, the EBs on tissue-culture plates, most of the EB-derived cells were found to display the morphologic features of hepatocytes, as well as albumin synthesis. In addition, the EB-derived cells grown in the rotating bioreactor exhibited higher levels of liver-specific functions, such as glycogen storage, cytochrome P450 activity, low-density lipoprotein, and indocyanine green uptake, than did differentiated cells grown in static culture. When the EB-derived cells from day-14 EBs and the cells’ culture supernatant were injected into nude mice, the transplanted cells were engrafted into the recipient livers.

Conclusions

Large quantities of high-quality hepatocytes can be generated from mES cells in a rotating bioreactor via EB formation. This system may be useful in the large-scale generation of hepatocytes for both cell transplantation and the development of bioartificial livers.

Polypeptide thermogels as a three dimensional culture scaffold for hepatogenic differentiation of human tonsil-derived mesenchymal stem cells

Tonsil-derived mesenchymal stem cells (TMSCs) were investigated for hepatogenic differentiation in the 3D matrixes of poly(ethylene glycol)-b-poly(l-alanine) (PEG-L-PA) thermogel. The diblock polymer formed β-sheet based fibrous nanoassemblies in water, and the aqueous polymer solution undergoes sol-to-gel transition as the temperature increases in a concentration range of 5.0-8.0 wt %. The cell-encapsulated 3D matrix was prepared by increasing the temperature of the cell-suspended PEG-L-PA aqueous solution (6.0 wt %) to 37 °C. The gel modulus at 37 °C was about 1000 Pa, which was similar to that of decellularized liver tissue. Cell proliferation, changes in cell morphology, hepatogenic biomarker expressions, and hepatocyte-specific biofunctions were compared for the following 3D culture systems: TMSC-encapsulated thermogels in the absence of hepatogenic growth factors (protocol M), TMSC-encapsulated thermogels where hepatogenic growth factors were supplied from the medium (protocol MGF), and TMSC-encapsulated thermogels where hepatogenic growth factors were coencapsulated with TMSCs during the sol-to-gel transition (protocol GGF). The spherical morphology and size of the encapsulated cells were maintained in the M system during the 3D culture period of 28 days, whereas the cells changed their morphology and significant aggregation of cells was observed in the MGF and GGF systems. The hepatocyte-specific biomarker expressions and metabolic functions were negligible for the M system. However, hepatogenic genes of albumin, cytokeratin 18 (CK-18), and hepatocyte nuclear factor 4α (HNF 4α) were significantly expressed in both MGF and GGF systems. In addition, production of albumin and α-fetoprotein was also significantly observed in both MGF and GGF systems. The uptake of cardiogreen and low-density lipoprotein, typical metabolic functions of hepatocytes, was apparent for MGF and GGF. The above data indicate that the 3D culture system of PEG-L-PA thermogels provides cytocompatible microenvironments for hepatogenic differentiation of TMSCs. In particular, the successful results of the GGF system suggest that the PEG-L-PA thermogel can be a promising injectable tissue engineering system for liver tissue regeneration after optimizing the aqueous formulation of TMSCs, hepatogenic growth factors, and other biochemicals.

Liver cell therapy and tissue engineering for transplantation

Liver transplantation remains the only definitive treatment for liver failure and is available to only a tiny fraction of patients with end-stage liver diseases. Major limitations for the procedure include donor organ shortage, high cost, high level of required expertise, and long-term consequences of immune suppression. Alternative cell-based liver therapies could potentially greatly expand the number of patients provided with effective treatment. Investigative research into augmenting or replacing liver function extends into three general strategies. Bioartificial livers (BALs) are extracorporeal devices that utilize cartridges of primary hepatocytes or cell lines to process patient plasma. Injection of liver cell suspensions aims to foster organ regeneration or provide a missing metabolic function arising from a genetic defect. Tissue engineering recreates the organ in vitro for subsequent implantation to augment or replace patient liver function. Translational models and clinical trials have highlighted both the immense challenges involved and some striking examples of success.

Fumarylacetoacetate hydrolase deficient pigs are a novel large animal model of metabolic liver disease

Hereditary tyrosinemia type I (HT1) is caused by deficiency in fumarylacetoacetate hydrolase (FAH), an enzyme that catalyzes the last step of tyrosine metabolism. The most severe form of the disease presents acutely during infancy, and is characterized by severe liver involvement, most commonly resulting in death if untreated. Generation of FAH(+/-) pigs was previously accomplished by adeno-associated virus-mediated gene knockout in fibroblasts and somatic cell nuclear transfer. Subsequently, these animals were outbred and crossed to produce the first FAH(-/-) pigs. FAH-deficiency produced a lethal defect in utero that was corrected by administration of 2-(2-nitro-4-trifluoromethylbenzoyl)-1,3 cyclohexanedione (NTBC) throughout pregnancy. Animals on NTBC were phenotypically normal at birth; however, the animals were euthanized approximately four weeks after withdrawal of NTBC due to clinical decline and physical examination findings of severe liver injury and encephalopathy consistent with acute liver failure. Biochemical and histological analyses, characterized by diffuse and severe hepatocellular damage, confirmed the diagnosis of severe liver injury. FAH(-/-) pigs provide the first genetically engineered large animal model of a metabolic liver disorder. Future applications of FAH(-/-) pigs include discovery research as a large animal model of HT1 and spontaneous acute liver failure, and preclinical testing of the efficacy of liver cell therapies, including transplantation of hepatocytes, liver stem cells, and pluripotent stem cell-derived hepatocytes.

Stem cells in liver regeneration and their potential clinical applications

Stem cells constitute a population of "primitive cells" with the ability to divide indefinitely and give rise to specialized cells under special conditions. Because of these two characteristics they have received particular attention in recent decades. These cells are the primarily responsible factors for the regeneration of tissues and organs and for the healing of lesions, a feature that makes them a central key in the development of cell-based medicine, called Regenerative Medicine. The idea of wound and organ repair and body regeneration is as old as the mankind, reflecting the human desire for inhibiting aging and immortality and it is first described in the ancient Greek myth of Prometheus. It is of interest that the myth refers to liver, an organ with remarkable regenerative ability after loss of mass and function caused by liver injury or surgical resection. Over the last decade there has been an important progress in understanding liver physiology and the mechanisms underlying hepatic development and regeneration. As liver transplantation, despite its difficulties, remains the only effective therapy for advanced liver disease so far, scientific interest has nowadays been orientated towards Regenerative Medicine and the use of stem cells to repair damaged liver. This review is focused on the available literature concerning the role of stem cells in liver regeneration. It summarizes the results of studies concerning endogenous liver regeneration and stem cell experimental protocols. Moreover, this review discusses the clinical studies that have been conducted in humans so far.

Establishment and directed differentiation of induced pluripotent stem cells from glycogen storage disease type Ib patient

Glycogen storage disease type Ib (GSDIb) is caused by a deficiency in the glucose-6-phosphate transporter (G6PT), which leads to neutrophil dysfunction. However, the underlying causes of these dysfunctions and their relationship with glucose homeostasis are unclear. Induced pluripotent stem cells (iPSCs) hold a great promise for advances in developmental biology, cell-based therapy and modeling of human disease. Here, we examined the use of iPSCs as a model for GSDIb. In this study, one 2-year-old patient was genetically screened and diagnosed with GSDIb. We established iPSCs and differentiated these cells into hepatocytes and neutrophils, which comprise the main pathological components of GSDIb. Cells that differentiated into hepatocytes exhibited characteristic albumin secretion and indocyanine green uptake. Moreover, iPSC-derived cells generated from patients with GSDIb metabolic abnormalities recapitulated key pathological features of the diseases affecting the patients from whom they were derived, such as glycogen, lactate, pyruvate and lipid accumulation. Cells that were differentiated into neutrophils also showed the GSDIb pathology. In addition to the expression of neutrophil markers, we showed increased superoxide anion production, increased annexin V binding and activation of caspase-3 and caspase-9, consistent with the GSDIb patient's neutrophils. These results indicate valuable tools for the analysis of this pathology and the development of future treatments.

Induced maturation of hepatic progenitor cells in vitro

Hepatic progenitor cells (HPCs) are a potential cell source for liver cell transplantation but do not function like mature liver cells. We sought an effective and reliable method to induce HPC maturation. An immortalized HP14.5 albumin promoter-driven Gaussian luciferase (ALB-GLuc) cell line was established from HPCs isolated from fetal mouse liver of post coitus day 14.5 mice to investigate the effect of induction factors on ALB promoter. HP14.5 parental cells were cultured in DMEM with different combinations of 2% horse serum (HS), 0.1 µM dexamethasone (DEX), 10 ng/mL hepatic growth factor (HGF), and/or 20 ng/mL fibroblast growth factor 4 (FGF4). Trypan blue and crystal violet staining were used to assess cell proliferation with different induction conditions. Expression of hepatic markers was measured by semi-quantitative RT-PCR, Western blot, and immunofluorescence. Glycogen storage and metabolism were detected by periodic acid-Schiff and indocyanine green (ICG) staining. GLuc activity indicated ALB expression. The combination of 2% HS+0.1 µM Dex+10 ng/mL HGF+20 ng/mL FGF4 induced the highest ALB-GLuc activity. Cell proliferation decreased in 2% HS but increased by adding FGF4. Upon induction, and consistent with hepatocyte development, DLK, AFP, and CK19 expression decreased, while ALB, CK18, and UGT1A expression increased. The maturity markers tyrosine aminotransferase and apolipoprotein B were detected at days 3 and 6 post-induction, respectively. ICG uptake and glycogen synthesis were detectable at day 6 and increased over time. Therefore, we demonstrated that HPCs were induced to differentiate into functional mature hepatocytes in vitro, suggesting that factor-treated HPCs may be further explored as a means of liver cell transplantation.

Production of hepatocyte-like cells from human pluripotent stem cells

Large-scale production of hepatocytes from a variety of genetic backgrounds would be beneficial for drug screening and to provide a source of cells to be used as a substitute for liver transplantation. However, fully functional primary hepatocytes remain difficult to expand in vitro, and circumventing this problem by using an alternative source of cells is desirable. Here we describe a 25-d protocol to direct the differentiation of human pluripotent stem cells into a near-homogenous population of hepatocyte-like cells. As cells progress through this protocol, they express genes in a chronological manner similar to that described during in vivo hepatic development. The protocol relies on culture systems devoid of serum, feeders or complex extracellular matrices, which enable molecular analyses without interference from unknown factors. This approach works efficiently with human embryonic stem cells and human induced pluripotent stem cells and was recently used to model liver diseases in vitro.

Production of hepatocyte-like cells from human pluripotent stem cells

Large-scale production of hepatocytes from a variety of genetic backgrounds would be beneficial for drug screening and to provide a source of cells to be used as a substitute for liver transplantation. However, fully functional primary hepatocytes remain difficult to expand in vitro, and circumventing this problem by using an alternative source of cells is desirable. Here we describe a 25-d protocol to direct the differentiation of human pluripotent stem cells into a near-homogenous population of hepatocyte-like cells. As cells progress through this protocol, they express genes in a chronological manner similar to that described during in vivo hepatic development. The protocol relies on culture systems devoid of serum, feeders or complex extracellular matrices, which enable molecular analyses without interference from unknown factors. This approach works efficiently with human embryonic stem cells and human induced pluripotent stem cells and was recently used to model liver diseases in vitro.

Comparison of proliferation and differentiation potential between mouse primary hepatocytes and embryonic hepatic progenitor cells in vitro

Cell therapy may be a novel and effective treatment strategy for liver diseases, replacing liver transplantation. The potential of two alternative cell types (hepatic progenitor/stem cells and mature hepatocytes) has not yet been fully assessed; the issues of low amplification efficiency and recovery function remain to be resolved. In this study, we investigated the proliferation, differentiation and function of primary mouse mature hepatocytes and embryonic hepatic progenitor cells. Primary cells were obtained from the livers of mouse embryos at 14.5 days post coitus [hepatic progenitor 14.5d (HP14.5d) cells], as well as from the livers of 3-month-old mice [liver cells 3m (LC3m)]. Using trypan blue staining and crystal violet staining to detect cell viability, we found that compared with the limited growth capability of primary LC3m cells, primary HP14.5d cells exhibited an active cell proliferation; however, proliferative ability of passaged HP14.5d cells significantly decreased. After the HP14.5d cells were treated in hepatic induction medium, the expression of progenitor cell markers decreased and that of mature hepatic markers increased, to levels similar to those of LC3m cells. On day 12 of induction, the HP14.5d cells showed comparable indocyanine green (ICG) uptake and glycogen storage to that of the LC3m cells. Therefore, our study demonstrates that primary hepatic progenitor cells have a stronger proliferation capacity and differentiation potential, supporting their clinical application in liver cell transplantation.

Hepatic stellate cells promote the differentiation of embryonic stem cell-derived definitive endodermal cells into hepatic progenitor cells

AIM

Hepatic non-parenchymal cells are well known to be capable of providing an important microenvironment and growth factors for hepatic regeneration, but their capacity for directing embryonic stem cells (ESC) toward hepatocytes remains to be assessed. Thus, this study aims to investigate the role of hepatic stellate cells (HSC), the major type of hepatic non-parenchymal cells, in the differentiation of ESC as well as exploring the potentiality of ESC in regeneration medicine for cell-based therapy.

METHODS

A two-step differentiation procedure that utilized the capability of HSC to regulate proliferation and differentiation of hepatocytes was used to develop an approach for directing the differentiation of ESC towards hepatic progenitor cells. Mouse ESC were cultivated in a serum-free medium containing Activin A and fibroblast growth factor to generate definitive endodermal cells characterized by the CXCR4 cell-surface marker. After 6-8 days in culture, approximately 60% of the differentiated cells expressed CXCR4, and more than 90% of the CXCR4 positive cells could be recovered by cell sorting. The purified CXCR4 positive cells were co-cultured with mouse HSC as feeder cells in basal medium without additional hepatocyte growth factors. Differentiation was complete after 10-12 days of co-culture, and hepatic progenitor cell markers such as α-fetoprotein (afp) and albumin (alb) were detected in the terminally differentiated ESC.

CONCLUSION

These results show that HSC provide an appropriate microenvironment and pivotal growth factors for generation of hepatic progenitor cells from ESC-derived definitive endodermal cells, and suggest that this approach possibly allows for hepatic differentiation of ESC imitating the process of hepatic regeneration.

Human decidua-derived mesenchymal stromal cells differentiate into hepatic-like cells and form functional three-dimensional structures

BACKGROUND AIMS

Previously, we have shown that human decidua-derived mesenchymal stromal cells (DMSC) are mesenchymal stromal cells (MSC) with a clonal differentiation capacity for the three embryonic layers. The endodermal capacity of DMSC was revealed by differentiation into pulmonary cells. In this study, we examined the hepatic differentiation of DMSC.

METHODS

DMSC were cultured in hepatic differentiation media or co-cultured with murine liver homogenate and analyzed with phenotypic, molecular and functional tests.

RESULTS AND CONCLUSIONS

DMSC in hepatic differentiation media changed their fibroblast morphology to a hepatocyte-like morphology and later formed a 3-dimensional (3-D) structure or hepatosphere. Moreover, the hepatocyte-like cells and the hepatospheres expressed liver-specific markers such as synthesis of albumin (ALB), hepatocyte growth factor receptor (HGFR), α-fetoprotein (AFP) and cytokeratin-18 (CK-18), and exhibited hepatic functions including glycogen storage capacity and indocyanine green (ICG) uptake/secretion. Human DMSC co-cultured with murine liver tissue homogenate in a non-contact in vitro system showed hepatic differentiation, as evidenced by expression of AFP and ALB genes. The switch in the expression of these two genes resembled liver development. Indeed, the decrease in AFP and increase in ALB expression throughout the co-culture were consistent with the expression pattern observed during normal liver organogenesis in the embryo. Interestingly, AFP and ALB expression was significantly higher when DMSC were co-cultured with injured liver tissue, indicating that DMSC respond differently under normal and pathologic micro-environmental conditions. In conclusion, DMSC-derived hepatospheres and DMSC co-cultured with liver homogenate could be suitable in vitro models for toxicologic, developmental and pre-clinical hepatic regeneration studies.

Differentiation and selection of hepatocyte precursors in suspension spheroid culture of transgenic murine embryonic stem cells

Embryonic stem cell-derived hepatocyte precursor cells represent a promising model for clinical transplantations to diseased livers, as well as for establishment of in vitro systems for drug metabolism and toxicology investigations. This study aimed to establish an in vitro culture system for scalable generation of hepatic progenitor cells. We used stable transgenic clones of murine embryonic stem cells possessing a reporter/selection vector, in which the enhanced green fluorescent protein- and puromycin N-acetyltransferase-coding genes are driven by a common alpha-fetoprotein gene promoter. This allowed for "live" monitoring and puromycin selection of the desired differentiating cell type possessing the activated alpha-fetoprotein gene. A rotary culture system was established, sequentially yielding initially partially selected hepatocyte lineage-committed cells, and finally, a highly purified cell population maintained as a dynamic suspension spheroid culture, which progressively developed the hepatic gene expression phenotype. The latter was confirmed by quantitative RT-PCR analysis, which showed a progressive up-regulation of hepatic genes during spheroid culture, indicating development of a mixed hepatocyte precursor-/fetal hepatocyte-like cell population. Adherent spheroids gave rise to advanced differentiated hepatocyte-like cells expressing hepatic proteins such as albumin, alpha-1-antitrypsin, cytokeratin 18, E-cadherin, and liver-specific organic anion transporter 1, as demonstrated by fluorescent immunostaining. A fraction of adherent cells was capable of glycogen storage and of reversible up-take of indocyanine green, demonstrating their hepatocyte-like functionality. Moreover, after transplantation of spheroids into the mouse liver, the spheroid-derived cells integrated into recipient. These results demonstrate that large-scale hepatocyte precursor-/hepatocyte-like cultures can be established for use in clinical trials, as well as in in vitro screening assays.

Single-step protocol for the differentiation of human-induced pluripotent stem cells into hepatic progenitor-like cells

Induced pluripotent stem (iPS) cells are ideal sources of hepatocyte for transplantation into patients experiencing hepatic failure. Growth and transcription factors were analyzed to design a single-step protocol for the differentiation of iPS cells into hepatocytes. The expression of transcription factors was analyzed using reverse transcription-polymerase chain reaction (RT-PCR) and compared among iPS cells, as well as fetal and adult liver cells. iPS cells were cultured with growth factors and RT-PCR was performed to analyze the expression of transcription factors. iPS cells were introduced with transcription factors, cultured with growth factors and subjected to real-time quantitative PCR. Indocyanine green (ICG) was added to the medium as a hepatocyte marker. Sox17, GATA4, GATA6, FoxA2, HEX, HNF4α and C/EBPα were expressed in fetal and adult liver cells, but not in iPS cells. Sox17, GATA6 and HNF4α were expressed after exposure a combination of oncostatin M, epidermal growth factor, retinoic acid, dexamethasone and ITS (OERDITS). When iPS cells were introduced with FoxA2, GATA4, HEX and C/EBPα and cultured with OERDITS for 8 days, the cells expressed α-fetoprotein, δ-like (Dlk)-1 and γ-glutamyl transpeptidase (GTP), and ICG uptake was observed. Exposure to FoxA2, GATA4, HEX and C/EBPα and culturing with OERDITS supplementation potentially serves as a single-step inducer for the differentiation of iPS cells into hepatic progenitor-like cells within 8 days.

Differentiation and transplantation of functional pancreatic beta cells generated from induced pluripotent stem cells derived from a type 1 diabetes mouse model

The nonobese diabetic (NOD) mouse is a classical animal model for autoimmune type 1 diabetes (T1D), closely mimicking features of human T1D. Thus, the NOD mouse presents an opportunity to test the effectiveness of induced pluripotent stem cells (iPSCs) as a therapeutic modality for T1D. Here, we demonstrate a proof of concept for cellular therapy using NOD mouse-derived iPSCs (NOD-iPSCs). We generated iPSCs from NOD mouse embryonic fibroblasts or NOD mouse pancreas-derived epithelial cells (NPEs), and applied directed differentiation protocols to differentiate the NOD-iPSCs toward functional pancreatic beta cells. Finally, we investigated whether the NPE-iPSC-derived insulin-producing cells could normalize hyperglycemia in transplanted diabetic mice. The NOD-iPSCs showed typical embryonic stem cell-like characteristics such as expression of markers for pluripotency, in vitro differentiation, teratoma formation, and generation of chimeric mice. We developed a method for stepwise differentiation of NOD-iPSCs into insulin-producing cells, and found that NPE-iPSCs differentiate more readily into insulin-producing cells. The differentiated NPE-iPSCs expressed diverse pancreatic beta cell markers and released insulin in response to glucose and KCl stimulation. Transplantation of the differentiated NPE-iPSCs into diabetic mice resulted in kidney engraftment. The engrafted cells responded to glucose by secreting insulin, thereby normalizing blood glucose levels. We propose that NOD-iPSCs will provide a useful tool for investigating genetic susceptibility to autoimmune diseases and generating a cellular interaction model of T1D, paving the way for the potential application of patient-derived iPSCs in autologous beta cell transplantation for treating diabetes.

Embryonic hepatocyte transplantation for hepatic cirrhosis: Efficacy and mechanism of action

AIM: To investigate the efficacy and mechanism of action of allogeneic embryonic hepatocyte transplantation for the treatment of hepatic cirrhosis.

METHODS: Rat embryonic hepatocytes were characterized by examining cell markers. Wistar rats with CCl₄-induced cirrhosis were randomly divided into two groups: a model group receiving continuous CCl₄, and a cell transplantation group receiving continuous CCl₄ and transplanted with embryonic fluorescent-labeled hepatocytes. In addition, a normal control group was composed of healthy rats. All rats were sacrificed after 2 wk following the initiation of the cell transplant. Ultrasound, pathological analyses and serum biochemical tests were used to evaluate the efficacy of embryonic hepatocyte transplantation. To analyze the recovery status of cirrhotic hepatocytes and the signaling pathways influenced by embryonic hepatocyte transplantation, real-time polymerase chain reaction was performed to examine the mRNA expression of stellate activation-associated protein (STAP), c-myb, α smooth muscle actin (α-SMA) and endothelin-1 (ET-1). Western blotting and immunohistochemistry were employed to detect α-SMA and ET-1 protein expression in hepatic tissues.

RESULTS: Gross morphological, ultrasound and histopathological examinations, serum biochemical tests and radioimmunoassays demonstrated that hepatic cirrhosis was successfully established in the Wistar rats. Stem cell factor receptor (c-kit), hepatocyte growth factor receptor (c-Met), Nestin, α fetal protein, albumin and cytokeratin19 markers were observed in the rat embryonic hepatocytes. Following embryonic hepatocyte transplantation, there was a significant reversal in the gross appearance, ultrasound findings, histopathological properties, and serum biochemical parameters of the rat liver. In addition, after the activation of hepatic stellate cells and STAP signaling, α-SMA, c-myb and ET-1 mRNA levels became significantly lower than in the untreated cirrhotic group (P < 0.05). These levels, however, were not statistically different from those of the normal healthy group. Immunohistochemical staining and Western blot analyses revealed that α-SMA and ET-1 protein expression levels in the transplantation group were significantly lower than in the untreated cirrhotic group, but being not statistically different from the normal group.

CONCLUSION: Transplantation of embryonic hepatocytes in rats has therapeutic effects on cirrhosis. The described treatment may significantly reduce the expression of STAP and ET-1.