Let-7f microRNA negatively regulates hepatic differentiation of human adipose tissue-derived stem cells

MicroRNAs (miRNAs) are noncoding RNAs involved in the regulation of the diverse biological processes such as metabolism, proliferation, and cell cycle, in addition to regulation of differentiation. So far, some miRNAs have been recognized to have important role in regulating hepatic functions. Statistically, let-7f has been revealed as a negative regulator of hepatic differentiation. In the present study, we investigated the effect of let-7f on hepatic differentiation of human adipose tissue-derived stem cells (hADSCs). hADSCs were transduced with recombinant lentivirus containing human inhibitor let-7 f. The expression of hepatocyte nuclear factors alpha (HNF4a), albumin (ALB), alpha fetoprotein (AFP), cytokeratin 18 (CK18), and cytokeratin 19 (CK19) was evaluated using quantitative real-time PCR (qRT-PCR). Immunocytochemistry was used to investigate the expression levels of the hepatocyte markers including ALB, AFP, and HNF4a, and biochemical analysis was implemented for hepatic function, glycogen deposition, and urea secretion. qRT-PCR showed significant upregulation in HNF4a, ALB, AFP, CK18, and CK19 expression in cells transduced with let-7f inhibitor lentiviruses. Moreover, positive staining was detected for ALB, AFP, and HNF4a using immunocytochemistry. Urea production and glycogen deposits were also found in the treated cells, the two specific features of the hepatic cells. Therefore, let-7f silencing led to the increased expression of the hepatocyte-specific factors and the accelerated hADSCs hepatic differentiation. Summing all these finding together, our present report has provided evidences that inhibition of let-7f would facilitate induction of hADSCs into hepatocyte-like cells and possibly in regenerative therapy of the liver disease in a wider spectrum.     

茵陈四苓颗粒对肝衰竭环境下骨髓间充质干细胞分化及IDO蛋白表达的影响

目的:研究肝衰竭体外模型环境下茵陈四苓颗粒对骨髓间充质干细胞的肝向分化及IDO蛋白表达的影响。方法:通过建立肝衰竭血清、中药干预血清、健康血清分别与骨髓间充质干细胞(BMSCs)共培养体系,检测BMSCs中CK18免疫荧光表达,Western-blot法检测甲胎蛋白(AFP)、肝组织白蛋白(ALB)、吲哚胺2,3—双加氧酶(IDO)蛋白表达。结果:1、CK18免疫荧光结果显示肝衰竭组及中药干预组染色均为弱阳性,但后者染色更强,而健康组无阳性染色;2、AFP、ALB在健康组、肝衰竭组、中药干预组均有表达,且各组间ALB比较均有差异(P0.05),三组AFP表达水平逐渐增高,各组间差异有统计学意义。IDO蛋白在健康组无表达,肝衰竭组表达低于中药干预组,且两组间差异具有统计学意义。结论:茵陈四苓颗粒能增强BMSCs在肝衰竭环境下的肝向分化趋势及免疫调节活性。     

Efficient generation of functional hepatocyte-like cells from human fetal hepatic progenitor cells in vitro

Differentiation of human hepatic progenitor cells to functional hepatocytes holds great potential to develop new therapeutic strategies for liver disease and to provide a platform for drug toxicity screens and identification of novel pharmaceuticals. We report here that human fetal hepatic progenitor cells (hFHPCs) efficiently differentiate to hepatocyte-like cells by continuous exposure to a combination of soluble factors for 7 days in vitro. We compared the effect of hepatocyte growth factor (HGF), oncostatin M (OSM), dexamethasone (DEX), or a combination on the expression of a liver-specific marker, albumin (ALB). Real-time RT-PCR analysis showed that, upon exposure to a combination of OSM, DEX, and HGF, the expression of ALB gradually increased in a time-dependent manner. In contrast, the level of the hepatic progenitor cell marker alpha-fetoprotein (AFP) decreased as differentiation progressed. Moreover, cells exposed to the combination of OSM, DEX, and HGF gradually featured highly differentiated hepatic functions, including ALB secretion, glycogen storage, urea production, and cytochrome P450 (CYP) activity. The effect of these factors on the differentiation of hFHPCs may be blocked by U0126, an inhibitor of the ERK1/2 signaling pathway. In conclusion, we demonstrate that a combination of soluble factors facilitates the efficient generation of highly differentiated hepatocyte-like cells from hFHPCs and ERK1/2 signaling pathway involved in this process. Results suggest that this system will be useful for generating functional hepatocytes and, hence, may serve as a cell source suitable for preclinical pharmacological research and testing.     

Derivation and Characterization of Hepatic Progenitor Cells from Human Embryonic Stem Cells

The derivation of hepatic progenitor cells from human embryonic stem (hES) cells is of value both in the study of early human liver organogenesis and in the creation of an unlimited source of donor cells for hepatocyte transplantation therapy. Here, we report for the first time the generation of hepatic progenitor cells derived from hES cells. Hepatic endoderm cells were generated by activating FGF and BMP pathways and were then purified by fluorescence activated cell sorting using a newly identified surface marker, N-cadherin. After co-culture with STO feeder cells, these purified hepatic endoderm cells yielded hepatic progenitor colonies, which possessed the proliferation potential to be cultured for an extended period of more than 100 days. With extensive expansion, they co-expressed the hepatic marker AFP and the biliary lineage marker KRT7 and maintained bipotential differentiation capacity. They were able to differentiate into hepatocyte-like cells, which expressed ALB and AAT, and into cholangiocyte-like cells, which formed duct-like cyst structures, expressed KRT19 and KRT7, and acquired epithelial polarity. In conclusion, this is the first report of the generation of proliferative and bipotential hepatic progenitor cells from hES cells. These hES cell–derived hepatic progenitor cells could be effectively used as an in vitro model for studying the mechanisms of hepatic stem/progenitor cell origin, self-renewal and differentiation.     

Differentiation of human embryonic stem cells into hepatocytes in 2D and 3D culture systems in vitro

Human embryonic stem cells (hESCs) have enormous potential as a source of cells for cell replacement therapies and as a model for early human development. In this study we examined the differentiating potential of hESCs into hepatocytes in two- and three-dimensional (2D and 3D) culture systems. Embryoid bodies (EBs) were inserted into a collagen scaffold 3D culture system or cultured on collagen-coated dishes and stimulated with exogenous growth factors to induce hepatic histogenesis. Immunofluorescence analysis revealed the expression of albumin (ALB) and cytokeratin-18 (CK-18). The differentiated cells in 2D and 3D culture system displayed several characteristics of hepatocytes, including expression of transthyretin, alpha-1-antitrypsin, cytokeratin 8, 18, 19, tryptophan-2,3-dioxygenase, tyrosine aminotransferase, glucose-6-phosphatase (G6P), cytochrome P450 subunits 7a1 and secretion of alpha-fetoprotein (AFP) and ALB and production of urea. In 3D culture, ALB and G6P were detected earlier and higher levels of urea and AFP were produced, when compared with 2D culture. Electron microscopy of differentiated hESCs showed hepatocyte-like ultrastructure, including glycogon granules, well-developed Golgi apparatuses, rough and smooth endoplasmic reticuli and intercellular canaliculi. The differentiation of hESCs into hepatocyte-like cells within 3D collagen scaffolds containing exogenous growth factors, gives rise to cells displaying morphological features, gene expression patterns and metabolic activities characteristic of hepatocytes and may provide a source of differentiated cells for treatment of liver diseases.     

How important is differentiation in the therapeutic effect of mesenchymal stromal cells in liver disease?

Background aimsThe protocols for differentiation of hepatocyte-like cells (HLCs) from mesenchymal stromal cells (MSCs) have been well established. Previous data have shown that MSCs and their derived HLCs were able to engraft injured liver and alleviate injuries induced by carbon tetrachloride. The goal of the current study was to determine the differences of MSCs and their derived HLCs in terms of therapeutic functions in liver diseases.MethodsAfter hepatic differentiation of umbilical cord–derived MSCs in vitro, we detected both MSC and HLC expressions of adhesion molecules and chemokine receptor CXCR4 by flow cytometry; immunosuppressive potential and hepatocyte growth factor expression were determined by means of enzyme-linked immunosorbent assay. We compared the therapeutic effect for fulminant hepatic failure in a mouse model.ResultsMSC-derived-HLCs expressed lower levels of hepatocyte growth factor, accompanied by impaired immunosuppression in comparison with MSCs. Furthermore, undifferentiated MSCs showed rescuing potentials superior to those in HLCs for the treatment of fulminant hepatic failure.ConclusionsAfter differentiation, HLCs lost several major properties in comparison with undifferentiated MSCs, which are beneficial for their application in liver diseases. Undifferentiated MSCs may be more appropriate than are HLCs for the treatment of liver diseases.     

Establishment of lentiviral-vector-mediated model of human alpha-1 antitrypsin delivery into hepatocyte-like cells differentiated from mesenchymal stem cells

Alpha-1 antitrypsin (AAT) deficiency is a lethal hereditary disorder characterized by a severe diminution in plasma levels of AAT leading to progressive liver dysfunction. Since mesenchymal stem cells can differentiate into hepatocyte-like cells they offer a potential unlimited source in autologous transplant procedures. The transfer of genetically modified hepatocyte cells derived from hMSCs into the body constitutes a novel paradigm of coupling cell therapy with gene therapy for this disease. hMSCs were isolated by density gradient centrifugation and plastic adherence. Hepatic differentiation was induced by exposing hMSC to induction medium for up to 21 days. The mRNA levels and protein expression of several important hepatic genes were determined using RT-PCR and immunocytochemistry. The chimeric AAT-Jred transgene was transferred to differentiated cells using a lentiviral vector and its expression was visualized by fluorescent microscopy. Flow cytometric analysis confirmed that hMSCs were obtained. Major hepatocyte marker genes expression were confirmed by RT-PCR and immunocytochemistry. AAT gene was successfully introduced into hepatocyte-like cells differentiated from hMSCs. This established system could be suitable for generation of hMSC derived hepatocyte-like cells containing the normal AAT gene, thus offering a potential in vitro source of cells for transplantation therapy of liver diseases in AAT-deficient patients.     

Hybrid poly-l-lactic acid/poly(ε-caprolactone) nanofibrous scaffold can improve biochemical and molecular markers of human induced pluripotent stem cell-derived hepatocyte-like cells

A suitable alternative strategy for liver transplantation is the use of nanofibrous scaffolds together with stem cells. In this study, a random hybrid of poly-l -lactic acid (PLLA) and poly(ε-caprolactone) (PCL) was used as a three-dimensional (3D) culture for differentiation of hepatocyte-like cells and compared with routine culture (two-dimensional [2D]). The expression of the endodermal marker, forkhead box A2 (FOXA2), was assessed on Day 3 and the hepatic markers; albumin (ALB), α-1 antitrypsin (AAT), and cytokeratin-18 (CK-18) were evaluated on Day 18 using quantitative polymerase chain reaction qPCR. As well as, ALB, α-fetoprotein (AFP), and low-density lipoprotein (LDL) uptake were evaluated using immunocytochemistry; moreover, periodic acid-Schiff and Oil Red were done by cell staining. In addition, AFP and urea production were evaluated by chemiluminescence and colorimetric assays. Light and scanning electron microscopy (SEM) showed changes in the cells in 2D and 3D models. The gene expression of hepatic markers was significantly higher in the 3D cultures. In addition, immunocytochemistry and cell staining showed that ALB, AFP, LDL-uptake, periodic acid-Schiff, and Oil Red were expressed in both cells derived on 2D and 3D. Furthermore, the evaluation of AFP and urea secretion was significantly different between 2D and 3D strategies. These findings suggest that functionally cells cultured on a PLLA/PCL scaffold may be suitable for cell therapy and regenerative medicine.     

The differentiation of hepatocyte-like cells from monkey embryonic stem cells

Embryonic stem cells (ESC) hold great potential for the treatment of liver diseases. Here, we report the differentiation of rhesus macaque ESC along a hepatocyte lineage. The undifferentiated monkey ESC line, ORMES-6, was cultured in an optimal culture condition in an effort to differentiate them into hepatocyte-like cells in vitro. The functional efficacy of the differentiated hepatic cells was evaluated using RT-PCR for the expression of hepatocyte specific genes, and Western blot analysis and immunocytochemistry for hepatic proteins such as alpha-fetoprotein (AFP), albumin and alpha1-antitrypsin (alpha1-AT). Functional assays were performed using the periodic acid schiff (PAS) reaction and ELISA. The final yield of ESC-derived hepatocyte-like cells was measured by flow cytometry for cells that were transduced with a liver-specific lentivirus vector containing the alpha1-AT promoter driving the expression of green fluorescence protein (GFP). The treatment of monkey ESC with an optimal culture condition yielded hepatocyte-like cells that expressed albumin, alpha1-AT, AFP, hepatocyte nuclear factor 3beta, glucose-6-phophatase, and cytochrome P450 genes and proteins as determined by RT-PCR and Western blot analysis. Immunofluorescent staining showed the cells positive for albumin, AFP, and alpha1-AT. PAS staining demonstrated that the differentiated cells showed hepatocyte functional activity. Albumin could be detected in the medium after 20 days of differentiation. Flow cytometry data showed that 6.5 +/- 1.0% of the total differentiated cells were positive for GFP. These results suggest that by using a specific, empirically determined, culture condition, we were able to direct monkey ESC toward a hepatocyte lineage.     

Differentiation and Migration of Bone Marrow Mesenchymal Stem Cells Transplanted through the Spleen in Rats with Portal Hypertension

Aims

The goals of this paper were to evaluate the differentiation of bone marrow mesenchymal stem cells (BMSCs) into hepatocyte-like cells in vitro, and to determine whether stem cells can migrate and plant into the liver with portal hypertension accompanied by the end-stage of liver disease.

Methods

BMSCs were isolated from rats and amplified with hepatocyte growth factor (HGF) and fibroblast growth factor-4 (FGF-4). The expression of alpha-fetoprotein (AFP), cytokeratin 18 (CK-18), and albumin (ALB) was detected by immunofluorescence in induced cells. Rats were randomly divided into experimental (with common bile duct ligation) and control groups. After injection of fluorescence labeled cells, cell distribution was observed under a fluorescence microscope. The integrated optical density (IOD) and cell distribution scores were evaluated using Image-Pro Plus 6.0 software. The portal pressure was measured before the rats were killed.

Results

After being induced with HGF and FGF-4, the Golgi apparatus, endoplasmic reticulum, ribosomes, and mitochondria all significantly increased in the fifth generation cells. Immunofluorescent analysis showed that the induced cells expressed AFP, CK-18, and ALB. BMSCs were stained by CM-Dil, and the labeling rate was as high as 95.5%. The portal pressure in experimental group was much higher than that of the control group (18.04±2.35 vs. 9.75±1.40cm H₂O p<0.01). The IOD of transplanted cells in the experimental group was also significantly higher than that of the control group (11.30±2.09×10⁵ vs. 2.93±0.88×10⁵, p<0.01). In addition, the cell distribution score in the experimental group was lower than that of the control group (1.99±0.36 vs. 2.36±0.27, P<0.05).

Conclusions

The combination of HGF and FGF-4 induces the differentiation of BMSCs into hepatocyte-like cells, which express AFP, CK-18, and ALB. In addition, the recruitment of BMSCs (after transplantation in the spleen) was improved in rats with portal hypertension.     

Nanofiber-expanded stem cells mitigate liver fibrosis: Experimental study

ObjectivesThis study examines a pretreatment strategy to strengthen the hepatic lineage divergence of mesenchymal stem cells (MSCs).Design and methodsBMSCs were expanded in the presence or absence of nanofiber (NF) and treated with growth factors (GF) prior to transplantation. Thioacetamide (TA) was used for liver fibrosis induction and transplantation of NF-expanded BMSCs was compared biochemically and histologically to the cells expanded without NF scaffold.ResultsThe ultraweb NF caused better proliferation and characterization of MSCs. MSCs transplantation significantly improved liver functions, increased hepatic HGF and Bcl-2 levels, whereas decreased serum fibronectin, hepatic TNF-α and TGF-β1 levels. Hepatic HNF4α, FOXa2, CYP7a1 genes expression were enhanced while β-5-Tub and AFP genes expression were depressed. Histological study documented these results. Differentiated NF-MSCs showed pronounced enhancement of the aforementioned parameters as compared to differentiated MSCs in the absence of NF.Conclusionpretreatment with growth factors in the presence of NF augment homing, repopulation and hepatic differentiation abilities of MSCs and proves to be a promising approach for the treatment of liver fibrosis.     

Human bone marrow mesenchymal stem cells are resistant to HBV infection during differentiation into hepatocytes in vivo and in vitro

Hepatocyte-like cells induced from bone marrow mesenchymal stem cells (BMSCs) recover liver function in animal models with liver failure. Our initial findings revealed that human BMSCs improved liver function in hepatitis B patients with end stage liver disease. However, the susceptibility of BMSCs to HBV infection during induction toward hepatocytes remains unknown. We have assessed whether BMSCs-derived hepatocyte-like cells can function like liver cells and be infected by HBV. A new and efficient way to direct the differentiation of BMSCs into functional hepatocytes was developed. BMSCs obtained from hepatitis B patients were induced to differentiate into hepatocytes through exposure to HGF, FGF-4, and EGF. After 6 days of exposure, BMSCs-derived hepatocyte-like cells that expressed a subset of hepatic genes and showed hepatic functions were obtained. HBV was used to infect the differentiated cells, and subsequently these cells were assayed for the presence of HBeAg, HBsAg, and HBV DNA. BMSCs proved resistant to HBV infection, both in vitro and during differentiation into hepatocytes in vitro. This demonstrates that BMSCs are resistant to HBV infection. BMSCs are viable for transplantation and should facilitate further research exploring the in vivo HBV-resistance of the hepatocytes derived from BMSCs after transplantation, a characteristic that could form the basis for hepatocyte transplantation.     

Transdifferentiation of mouse BM cells into hepatocyte-like cells

BACKGROUND: During the past few years multiple studies have revealed that adult stem cells, including BM origin stem cells, can be transdifferentiated into various cell types, including hepatocyte-like cells, under proper treatments or in a suitable microenvironment. However, little is known about the mechanism of the transdifferentiation, and the treatments employed seem to be very complicated and require simplification. It is important to determine the suitable conditions in which BM cells would be efficiently differentiated into hepatocytes. METHODS: Mouse BM cells were isolated from femurs and tibias and cultured in IMDM supplemented with 10% FBS. Hepatic differentiation was induced in a differentiation medium containing 20 ng/mL HGF, 10 ng/mL FGF-4, 10 ng/mL Oncostatin M (OSM) and different concentrations of liver-injured mouse sera. The differentiated hepatic cells were characterized by the expression of liver-associated mRNA and proteins and morphologic and functional features. RESULTS: BM cell-derived polygonal cell colonies appeared after several days of culture, and these hepatocyte-like cells expressed AFP, HNF-3beta, CK19, CK18, ALB, TAT and G-6-Pase at mRNA and protein levels, and the cells also had some hepatic cellular functions, such as glycogen storage and urea production. Interestingly, suitable concentrations of sera from liver-injured mice added to this system showed strong stimulation on the in vitro transdifferentiation of mouse BM cells into hepatocytes. DISCUSSION: In the present study we have established an effective hepatic differentiation system by a combination of HGF, FGF-4, OSM and liver-injured mouse sera in vitro. Accordingly, it will be a useful resource not only for understanding the mechanisms of transdifferentiation but also for efficient amplification of hepatocyte progenitor cells of BM origin.     

DMSO Efficiently Down Regulates Pluripotency Genes in Human Embryonic Stem Cells during Definitive Endoderm Derivation and Increases the Proficiency of Hepatic Differentiation

BackgroundDefinitive endoderm (DE) is one of the three germ layers which during in vivo vertebrate development gives rise to a variety of organs including liver, lungs, thyroid and pancreas; consequently efficient in vitro initiation of stem cell differentiation to DE cells is a prerequisite for successful cellular specification to subsequent DE-derived cell types [1, 2]. In this study we present a novel approach to rapidly and efficiently down regulate pluripotency genes during initiation of differentiation to DE cells by addition of dimethyl sulfoxide (DMSO) to Activin A-based culture medium and report its effects on the downstream differentiation to hepatocyte-like cells.ResultsAddition of DMSO to the Activin A-based medium during DE specification resulted in rapid down regulation of the pluripotency genes OCT4 and NANOG, accompanied by an increase expression of the DE genes SOX17, CXCR4 and GATA4. Importantly, the expression level of ALB in DMSO-treated cells was also higher than in cells which were differentiated to the DE stage via standard Activin A treatment.