Proliferation Of Hepatic Progenitor Cells Research Articles

Transcriptional Control: A Directional Sign at the Crossroads of Adult Hepatic Progenitor Cells' Fates.

Hepatic progenitor cells (HPCs) have a bidirectional potential to differentiate into hepatocytes and bile duct epithelial cells and constitute a second barrier to liver regeneration in the adult liver. They are usually located in the Hering duct in the portal vein region where various cells, extracellular matrix, cytokines, and communication signals together constitute the niche of HPCs in homeostasis to maintain cellular plasticity. In various types of liver injury, different cellular signaling streams crosstalk with each other and point to the inducible transcription factor set, including FoxA1/2/3, YB-1, Foxl1, Sox9, HNF4α, HNF1α, and HNF1β. These transcription factors exert different functions by binding to specific target genes, and their products often interact with each other, with diverse cascades of regulation in different molecular events that are essential for homeostatic regulation, self-renewal, proliferation, and selective differentiation of HPCs. Furthermore, the tumor predisposition of adult HPCs is found to be significantly increased under transcriptional factor dysregulation in transcriptional analysis, and the altered initial commitment of the differentiation pathway of HPCs may be one of the sources of intrahepatic tumors. Related transcription factors such as HNF4α and HNF1 are expected to be future targets for tumor treatment.

Hepatic progenitor cell-originated ductular reaction facilitates liver fibrosis through activation of hedgehog signaling.

Background: It is poorly understood what cellular types participate in ductular reaction (DR) and whether DR facilitates recovery from injury or accelerates hepatic fibrosis. The aim of this study is to gain insights into the role of hepatic progenitor cell (HPC)-originated DR during fibrotic progression. Methods: DR in liver specimens of PBC, chronic HBV infection (CHB) or NAFLD, and four rodent fibrotic models by different pathogenic processes was evaluated. Gli1 expression was inhibited in rodent models or cell culture and organoid models by AAV-shGli1 or treating with GANT61. Results: Severity of liver fibrosis was positively correlated with DR extent in patients with PBC, CHB or NAFLD. HPCs were activated, expanded, differentiated into reactive cholangiocytes and constituted "HPC-originated DR", accompanying with exacerbated fibrosis in rodent models of HPC activation & proliferation (CCl4/2-AAF-treated), Μdr2-/- spontaneous PSC, BDL-cholestatic fibrosis or WD-fed/CCl4-treated NASH-fibrosis. Gli1 expression was significantly increased in enriched pathways in vivo and in vitro. Enhanced Gli1 expression was identified in KRT19+-reactive cholangiocytes. Suppressing Gli1 expression by administration of AAV-shGli1 or GANT61 ameliorated HPC-originated DR and fibrotic extent. KRT19 expression was reduced after GANT61 treatment in sodium butyrate-stimulated WB-F344 cells or organoids or in cells transduced with Gli1 knockdown lentiviral vectors. In contrast, KRT19 expression was elevated after transducing Gli1 overexpression lentiviral vectors in these cells. Conclusions: During various modes of chronic injury, Gli1 acted as an important mediator of HPC activation, expansion, differentiation into reactive cholangiocytes that formed DR, and subsequently provoked hepatic fibrogenesis.

The endocannabinoid system promotes hepatocyte progenitor cell proliferation and maturation by modulating cellular energetics

The proliferation and differentiation of hepatic progenitor cells (HPCs) drive the homeostatic renewal of the liver under diverse conditions. Liver regeneration is associated with an increase in Axin2+Cnr1+ HPCs, along with a marked increase in the levels of the endocannabinoid anandamide (AEA). But the molecular mechanism linking AEA signaling to HPC proliferation and/or differentiation has not been explored. Here, we show that in vitro exposure of HPCs to AEA triggers both cell cycling and differentiation along with increased expression of Cnr1, Krt19, and Axin2. Mechanistically, we found that AEA promotes the nuclear localization of the transcription factor β-catenin, with subsequent induction of its downstream targets. Systemic analyses of cells after CRISPR-mediated knockout of the β-catenin-regulated transcriptome revealed that AEA modulates β-catenin-dependent cell cycling and differentiation, as well as interleukin pathways. Further, we found that AEA promotes OXPHOS in HPCs when amino acids and glucose are readily available as substrates, but AEA inhibits it when the cells rely primarily on fatty acid oxidation. Thus, the endocannabinoid system promotes hepatocyte renewal and maturation by stimulating the proliferation of Axin2+Cnr1+ HPCs via the β-catenin pathways while modulating the metabolic activity of their precursor cells.

TWEAK/FN14 promotes profibrogenic pathway activation in Prominin-1-expressing hepatic progenitor cells in biliary atresia.

Biliary atresia (BA), a congenital cholestatic liver disease, commonly culminates in end-stage liver disease. We previously demonstrated in BA that Prominin-1 ( Prom1 )-expressing hepatic progenitor cells (HPCs) expand within regions of developing fibrosis, giving rise to cholangiocytes within biliary ductular reactions. Null mutation of Prom1 or ablation of cells expressing Prom1 significantly diminishes fibrogenesis. FN14, the receptor for TNF-like weak inducer of apoptosis (TWEAK), is expressed by HPCs. TWEAK/FN14 signaling promotes fibrosis in multiple organ systems. Therefore, we hypothesized that TWEAK/FN14 signaling mediates Prom1 -expressing HPC proliferation leading to profibrogenic ductular reactions in BA. The experimental mouse model of BA mediated by perinatal rhesus rotavirus (RRV) infection resulted in increased co-expression of Fn14 in Prom1 -expressing HPCs within regions of ductular reactions. FN14 antagonist L524-0366 decreased ductular reactions, biliary fibrosis and periportal fibroblast activation in RRV injury. L524-0366 inhibition also demonstrated loss of downstream noncanonical NF-kB signaling expression in RRV injury. Murine HPC organoids demonstrated accelerated organoid growth and proliferation when treated with recombinant TWEAK. Increased organoid proliferation with recombinant TWEAK was lost when also treated with L524-0366. Analysis of a large publicly available RNA sequencing database of BA and normal control patients revealed significant increases in expression of PROM1 , FN14 , and genes downstream of TNF signaling and noncanonical NF-κB signaling pathways in BA infants. Infants who failed to achieve bile drainage after hepatoportoenterostomy had higher relative levels of FN14 expression. TWEAK/FN14 signaling activation in Prom1 -expressing HPCs contributes to proliferation of profibrogenic ductular reactions in BA.

Clonorchis sinensis infection contributes to hepatocellular carcinoma progression in rat.

Clonorchis sinensis (C. sinensis) infection is a risk factor for cholangiocarcinoma. Whether it also contributes to the development of hepatocellular carcinoma (HCC) is still unclear. This study explored the potential relationship between C. sinensis infection and HCC. A total of 110 Sprague-Dawley rats were divided into four treatment groups, the negative control group (NC) received intragastric (i.g.) administration of saline, while the clonorchiasis group (CS) received i.g. administration of 150 C. sinensis metacercariae. The diethylnitrosamine-induced group (DEN) received intraperitoneal (i.p.) administration of DEN. The clonorchiasis DEN-induced group (CSDEN) received i.g. administration of 150 C. sinensis metacercariae followed by i.p. administration of DEN. Hematoxylin and eosin staining, immunohistochemistry, and Masson's trichrome staining were performed for histopathological analysis of the isolated tissues. RNA-seq technology and RT-PCR were employed for gene expression. In the DEN group, 15 rats survived, of which 9 developed liver cirrhosis and 7 developed HCC. In the CSDEN group, all of the 17 surviving rats developed cirrhosis, and 15 showed development of HCC. The incidence of liver cirrhosis and HCC was significantly higher in the CSDEN group than in the DEN group. KEGG pathway analysis of the differentially expressed genes suggested significant upregulation in inflammation-associated pathways. Immunohistochemistry and RT-PCR results showed significant upregulation of hepatic progenitor cell markers (CK19, SOX9, EpCAM) in the CS group compared to the NC group, as well as in the CSDEN group compared to the DEN group. Our study suggests that C. sinensis infection increases risk of HCC in a rat model by stimulating proliferation of hepatic progenitor cells.

P53 positively regulates the proliferation of hepatic progenitor cells promoted by laminin-521

Hepatic progenitor cells (HPCs) hold tremendous potential for liver regeneration, but their well-known limitation of proliferation hampers their broader use. There is evidence that laminin is required for the proliferation of HPCs, but the laminin isoform that plays the dominant role and the key intracellular downstream targets that mediate the regulation of HPC proliferation have yet to be determined. Here we showed that p53 expression increased gradually and reached maximal levels around 8 days when laminin α4, α5, β2, β1, and γ1 subunit levels also reached a maximum during HPC activation and expansion. Laminin-521 (LN-521) promoted greater proliferation of HPCs than do laminin, matrigel or other laminin isoforms. Inactivation of p53 by PFT-α or Ad-p53V143A inhibited the promotion of proliferation by LN-521. Further complementary MRI and bioluminescence imaging analysis showed that p53 inactivation decreased the proliferation of transplanted HPCs in vivo. p53 was activated by LN-521 through the Integrin α6β1/FAK-Src-Paxillin/Akt axis. Activated p53 was involved in the nuclear translocation of CDK4 and inactivation of Rb by inducing p27Kip1. Taken together, this study identifies LN-521 as an ideal candidate substrate for HPC culture and uncovers an unexpected positive role for p53 in regulating proliferation of HPCs, which makes it a potential target for HPC-based regenerative medicine.

Loss of YB-1 alleviates liver fibrosis by suppressing epithelial-mesenchymal transition in hepatic progenitor cells

Previously, we reported that the nuclear translocation of Y-box binding protein 1 (YB-1) is induced by transforming growth factor-β (TGF-β) and promotes hepatic progenitor cells (HPCs) expansion. Here, we explored the mechanisms underlying YB-1 translocation and the impact of YB-1 on the epithelial–mesenchymal transition (EMT) in HPCs. YB-1flox/floxcre+/− (YB-1f/fcre+/−) mice and YB-1f/fcre−/− mice were fed with a 3,5-diethoxycarbonyl-1,4-dihydrocollidine (DDC) or a choline-deficient, ethionine-supplemented (CDE) diet. Liver injury and fibrosis were assessed by performing hematoxylin and eosin (HE) and Masson staining. The expression of collagen and EMT-related markers (E-cadherin, N-cadherin, and Snail) was detected by reverse transcription-polymerase chain reaction (RT-PCR), western blotting, and immunofluorescence analyses. Protein kinase B (AKT) expression in HPCs was silenced via RNA interference. Nuclear YB-1 expression in HPCs was detected via western blotting and immunofluorescence analyses. HPC proliferation was detected by immunofluorescence. Our results indicate that YB-1 transcriptionally regulated the biological behavior of HPCs. HPC-specific YB-1 knockout alleviated liver fibrosis in mice fed with DDC or CDE diet. YB-1 nuclear translocation promoted matrix metallopeptidase 9 transcription. YB-1 depletion in HPCs significantly dampened the EMT and inhibited AKT phosphorylation in vitro and in vivo. AKT knockdown compromised TGF-β-induced YB-1 nuclear translocation, thereby inhibiting the EMT and HPC proliferation. EMT and AKT were highly activated in HPCs in cirrhotic livers. Collectively, our findings indicate that the loss of YB-1 suppressed EMT in HPCs and alleviated liver fibrosis in mice, and that AKT was essential for TGF-β-induced YB-1 nuclear translocation and HPC proliferation.

GITR/GITRL reverse signalling modulates the proliferation of hepatic progenitor cells by recruiting ANXA2 to phosphorylate ERK1/2 and Akt

Hepatic stem/progenitor cells are the major cell compartment for tissue repair when hepatocyte proliferation is compromised in chronic liver diseases, but the expansion of these cells increases the risk of carcinogenesis. Therefore, it is essential to explore the pathways restricting their expansion and abnormal transformation. The ligand of glucocorticoid-induced tumour necrosis factor receptor (GITRL) showed the most highly increased expression in hepatic progenitor cells treated with transforming growth factor (TGF)-β1. If overexpressed by hepatic progenitor cells, GITRL stimulated cell proliferation by activating the epithelial–mesenchymal transition pathway and enhancing ERK1/2 and Akt phosphorylation via GITRL binding to ANXA2. However, GITR, the specific GITRL receptor, suppressed the epithelial–mesenchymal transition pathway of GITRL-expressing cells and decreased their growth by dissociating ANXA2 from GITRL and reducing downstream ERK1/2 and Akt phosphorylation. This study identifies GITR/GITRL reverse signalling as a cross-interaction pathway between immune cells and hepatic stem/progenitor cells that restricts the expansion of hepatic stem/progenitor cells and reduces the possibility of carcinogenesis.

Specific knockdown of Y-box binding protein 1 in hepatic progenitor cells inhibits proliferation and alleviates liver fibrosis

The proliferation of hepatic progenitor cells (HPCs) contributes to liver regeneration and fibrogenesis during chronic liver injury; however, the mechanism modulating HPC proliferation remains unknown. Y-box binding protein-1 (YB-1) is a transcription factor that regulates the transcription of several genes and is highly expressed in liver injury. We explored the role of YB-1 in HPC proliferation and liver fibrosis. We detected increased expansion of HPCs and elevated levels of YB-1 in HPCs from patients with hepatitis B virus-related fibrosis and choline-deficient ethionine-supplemented or 5-diethoxycarbonyl-1,4-dihydrocollidine diet-induced mice compared with those in control groups. HPC-specific deletion of YB-1 using YB-1flox/flox; Foxl1-Cre+/- mice led to reduced HPC expansion and less collagen deposition in the liver tissues compared with that in Cre-/- mice. In cultured primary HPCs, YB-1 knockdown inhibited HPC proliferation. Further experiments indicated YB-1 negatively regulated p53 expression, and silencing of p53 blocked YB-1 knockdown-mediated inhibition of HPC proliferation. Collectively, YB-1 negatively regulates HPC proliferation and alleviates liver fibrosis by p53.

Hepatic progenitor cells promote the repair of schistosomiasis liver injury by inhibiting IL-33 secretion in mice

BackgroundHepatic schistosomiasis, a chronic liver injury induced by long-term Schistosoma japonicum (S. japonicum) infection, is characterized by egg granulomas and fibrotic pathology. Hepatic progenitor cells (HPCs), which are nearly absent or quiescent in normal liver, play vital roles in chronic and severe liver injury. But their role in the progression of liver injury during infection remains unknown.MethodsIn this study, the hepatic egg granulomas, fibrosis and proliferation of HPCs were analyzed in the mice model of S. japonicum infection at different infectious stages. For validating the role of HPCs in hepatic injury, tumor necrosis factor-like-weak inducer of apoptosis (TWEAK) and TWEAK blocking antibody were used to manipulate the proliferation of HPCs in wild-type and IL-33−/− mice infected with S. japonicum.ResultsWe found that the proliferation of HPCs was accompanied by inflammatory granulomas and fibrosis formation. HPCs expansion promoted liver regeneration and inhibited inflammatory egg granulomas, as well as the deposition of fibrotic collagen. Interestingly, the expression of IL-33 was negatively associated with HPCs’ expansion. There were no obvious differences of liver injury caused by infection between wild-type and IL-33−/− mice with HPCs’ expansion. However, liver injury was more attenuated in IL-33−/− mice than wild-type mice when the proliferation of HPCs was inhibited by anti-TWEAK.ConclusionsOur data uncovered a protective role of HPCs in hepatic schistosomiasis in an IL-33-dependent manner, which might provide a promising progenitor cell therapy for hepatic schistosomiasis.

TGF-β/YB-1/Atg7 axis promotes the proliferation of hepatic progenitor cells and liver fibrogenesis

Hepatic fibrosis is characterized by excessive extracellular matrix deposition and ductular reactions, manifested as the expansion of hepatic progenitor cells (HPCs). We previously reported that the Y-box binding protein 1 (YB-1) in HPCs is involved in chronic liver injury. In this study, we constructed YB-1f/f Foxl1-Cre mice and investigated the role of YB-1 in HPC expansion in murine choline-deficient, ethionine-supplemented (CDE), and 3,5-diethoxycarbonyl-1,4-dihydrocollidine (DDC) models. Liver injury and fibrosis were measured using hematoxylin and eosin (HE), Masson, and Sirius Red staining. HPC proliferation was detected using EdU and immunofluorescence (IF). Autophagic flow was measured by mCherry-GFP-LC3B staining and transmission electron microscopy (TEM). YB-1 expression was measured by immunofluorescence and western blotting. CUT & Tag analysis, chromatin immunoprecipitation, and RT-PCR were performed to explore the regulation of autophagy-related protein 7 (Atg7) transcription by YB-1. Our results indicated that liver injury was accompanied by high expression of YB-1, proliferative HPCs, and activated autophagy in the CDE and DDC models. YB-1f/f Cre+/− mice displayed less liver injury and fibrosis than YB-1f/f Cre−/− mice in the CDE and DDC models. YB-1 promoted proliferation and autophagy of HPCs in vitro and in vivo. Transforming growth factor-β (TGF-β) induced YB-1 nuclear translocation and facilitated the proliferation and autophagy of HPCs. YB-1 nuclear translocation promoted the transcription of Atg7, which is essential for TGF-β/YB-1 mediated HPCs expansion in vitro and in vivo. In summary, YB-1 nuclear translocation induced by TGF-β in HPCs promotes the proliferation and autophagy of HPCs and Atg7 participates in YB-1-mediated HPC-expansion and liver fibrosis.

Enrichment of progenitor cells by 2-acetylaminofluorene accelerates liver carcinogenesis induced by diethylnitrosamine in vivo.

The potential role of hepatocytes versus hepatic progenitor cells (HPC) on the onset and pathogenesis of hepatocellular carcinoma (HCC) has not been fully clarified. Because the administration of 2‐acetylaminofluorene (2AAF) followed by a partial hepatectomy, selectively induces the HPC proliferation, we investigated the effects of chronic 2AAF administration on the HCC development caused by the chronic administration of the carcinogen diethylnitrosamine (DEN) for 16 weeks in the rat. DEN + 2AAF protocol impeded weight gain of animals but promoted prominent hepatomegaly and exacerbated liver alterations compared to DEN protocol alone. The tumor areas detected by γ‐glutamyl transferase, prostaglandin reductase‐1, and glutathione S‐transferase Pi−1 liver cancer markers increased up to 80% as early as 12 weeks of treatment, meaning 6 weeks earlier than DEN alone. This protocol also increased the number of Ki67‐positive cells and those of CD90 and CK19, two well‐known progenitor cell markers. Interestingly, microarray analysis revealed that DEN + 2AAF protocol differentially modified the global gene expression signature and induced the differential expression of 30 genes identified as HPC markers as early as 6 weeks of treatment. In conclusion, 2AAF induces the early appearance of HPC markers and as a result, accelerates the hepatocarcinogenesis induced by DEN in the rat. Thus, since 2AAF simultaneously administrated with DEN enriches HPC during hepatocarcinogenesis, we propose that DEN + 2AAF protocol might be a useful tool to investigate the cellular origin of HCC with progenitor features.

FoxA2 inhibits the proliferation of hepatic progenitor cells by reducing PI3K/Akt/HK2‐mediated glycolysis

FoxA2 is an essential transcription factor for liver organogenesis and homeostasis. Although reduced expression of FoxA2 has been associated with chronic liver diseases, hepatic progenitor cells (HPCs) that are activated in these circumstances express FoxA2. However, the functional effects and underlying mechanism of FoxA2 in HPCs are still unknown. As revealed by immunostaining, HPCs expressed FoxA2 in human cirrhotic livers and in the livers of choline-deficient diet supplemented with ethionine (CDE) rats. Knocking down FoxA2 in HPCs isolated from CDE rats significantly increased cell proliferation and aerobic glycolysis. Moreover, gene transcription, protein expression, and the enzyme activities of hexokinase 2 (HK2) were upregulated, and blocking HK2 activities via 2-deoxyglucose markedly reduced cell proliferation and aerobic glycolysis. Kyoto Encyclopedia of Genes and Genomes analysis revealed that FoxA2 knockdown enhanced the transcription of genes involved in the phosphatidylinositol 3-kinase (PI3K)/protein kinase B (Akt) pathway and triggered downstream Akt phosphorylation. Blocking the PI3K/Akt pathway by Ly294002 inhibited HK2 activities, aerobic glycolysis, and cell proliferation in FoxA2-knockdown cells. Therefore, FoxA2 plays an important role in the proliferation and inhibition of HPCs by suppressing PI3K/Akt/HK2-regulated aerobic glycolysis.

Vascular Endothelial Growth Factor Promotes Proliferation of Epithelial Cell Adhesion Molecule–Positive Cells in Nonalcoholic Steatohepatitis

An impaired hepatocyte proliferation during severe liver injury causes the proliferation of hepatic progenitor cells (HPCs), also called as the ductular reaction (DR). In the present study, we studied the role of key angiogenic factors in HPC-mediated DR in nonalcoholic steatohepatitis (NASH). Liver biopsies from patients with NASH (n= 14) were included in the study. Patients with NASH were divided in two groups, early and late fibrosis (based on fibrosis staging). Biopsies were used to analyze the gene expression by quantitative real-time polymerase chain reaction and immunohistochemical (IHC) staining for two markers of DR, viz, CK19 and epithelial cell adhesion molecule (EpCAM). Cocultures were performed between steatotic human umbilical vein endothelial cells (HUVECs) and LX2 and Huh7 cells. Enzyme-linked immunosorbent assays were performed to measure levels of vascular endothelial growth factor (VEGF) in coculturestudies. Next, Huh7 cells were treated with VEGF, and proliferation was investigated by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium (MTT) assays. The number of EpCAM-positive cells was analyzed by flow cytometry. Of all the angiogenic factors, the gene expression of VEGFand angiopoietin 2 (Ang2) was significantly different between patients with NASH in the early and late fibrosis groups (P<0.05 for both). Both VEGF and Ang2 also correlated significantly with the IHC scores of CK19 and EpCAM in the study group. In the invitro studies, VEGF levels were significantly increased when Huh7 cells were cocultured with steatotic HUVECs and LX2 cells. The proliferation and percentage of EpCAM-positive cells was increased when Huh7 cells were treated with VEGF. Our study indicates an important contribution of VEGF towardthe activation of HPC-mediated regeneration and DR in NASH.

Ring1 promotes the transformation of hepatic progenitor cells into cancer stem cells through the Wnt/β-catenin signaling pathway.

The proliferation of hepatic progenitor cells (HPCs) is observed in reactive conditions of the liver and primary liver cancers. Ring1 as a member of polycomb-group proteins which play vital roles in carcinogenesis and stem cell self-renewal was increased in HCC patients and promoted proliferation and survival of cancer cell by degrading p53. However, the mechanisms of Ring1 driving the progression of hepatocarcinogenesis have not been elucidated. In this study, forced expression Ring1 and Ring1 siRNA lentiviral vectors were utilized to stably overexpression and silence Ring1 in HPC cell line (WB-F344), respectively. Our finding indicated that overexpression of Ring1 in HPCs promoted colony formation, cell multiplication, and invasion in vitro, conversely depletion of Ring1 repressed the biological functions of HPCs relative to controls. The expression of β-catenin was upregulated in the HPCs with overexpression of Ring1, and the correlation analysis also showed that β-catenin and Ring1 had a significant correlation in the liver cancer tissues and adjacent tissues. The activation of the Wnt/β-catenin signaling pathway significantly increased the expression of liver cancer stem cells related (LCSCs)-related molecular markers CD90 and EpCAM, which led to the transformation of HPCs into LCSCs. Most importantly, the injection of HPCs with overexpressed Ring1 into the subcutaneous of nude mice leads to the formation of poorly differentiated HCC neoplasm. Our findings elucidate that overexpression of Ring1 the activated Wnt/β-catenin signaling pathway and drove the transformation of HPCs into cancer stem cell-like cells, suggesting Ring1 has extraordinary potential in early diagnosis of HCC.

Functions and the Emerging Role of the Foetal Liver into Regenerative Medicine.

During foetal life, the liver plays the important roles of connection and transient hematopoietic function. Foetal liver cells develop in an environment called a hematopoietic stem cell niche composed of several cell types, where stem cells can proliferate and give rise to mature blood cells. Embryologically, at about the third week of gestation, the liver appears, and it grows rapidly from the fifth to 10th week under WNT/β-Catenin signaling pathway stimulation, which induces hepatic progenitor cells proliferation and differentiation into hepatocytes. Development of new strategies and identification of new cell sources should represent the main aim in liver regenerative medicine and cell therapy. Cells isolated from organs with endodermal origin, like the liver, bile ducts, and pancreas, could be preferable cell sources. Furthermore, stem cells isolated from these organs could be more susceptible to differentiate into mature liver cells after transplantation with respect to stem cells isolated from organs or tissues with a different embryological origin. The foetal liver possesses unique features given the co-existence of cells having endodermal and mesenchymal origin, and it could be highly available source candidate for regenerative medicine in both the liver and pancreas. Taking into account these advantages, the foetal liver can be the highest potential and available cell source for cell therapy regarding liver diseases and diabetes.

Regulation of Long Non-Coding RNA-Dreh Involved in Proliferation and Migration of Hepatic Progenitor Cells during Liver Regeneration in Rats.

Liver regeneration plays a significant role in protecting liver function after liver injury or chronic liver disease. Long non-coding RNAs (lncRNAs) are considered to be involved in the proliferation of hepatocytes and liver regeneration. Therefore, this study aimed to explore the effects of LncRNA-Dreh on the regulation of hepatic progenitor cells (HPCs) during liver regeneration in rats. Initially, the rat model of liver injury was established to investigate the effect of LncRNA-Dreh down-regulation on liver tissues of rats with liver injury. Subsequently, HPCs line WB-F344 cells were transfected with interference plasmid of LncRNA-Dreh and the expression of LncRNA-Dreh and Vimentin was detected. The proliferation and migration ability of WB-F344 cells, as well as the content of albumin (ALB) and alpha fetoprotein (AFP) in cell differentiation were then determined. Disorderly arranged structure of liver tissue, a large number of HPCs set portal area as center extended to hepatic lobule and ductular reaction were observed in liver tissues of rats with liver injury. The expression of LncRNA-Dreh decreased while Vimentin increased in liver tissues of rats with liver injury. Moreover, the proliferation and migration ability, expression of Vimentin and AFP in WB-F344 cells were increased after silencing of LncRNA-Dreh and ALB was decreased. Collectively, our findings demonstrate that inhibition of LncRNA-Dreh can enhance the proliferation and migration abilities of HPCs in liver regeneration but cause abnormal differentiation of HPCs.

Lipopolysaccharide induces the differentiation of hepatic progenitor cells into myofibroblasts constitutes the hepatocarcinogenesis-associated microenvironment.

Hepatocellular carcinoma (HCC) generally occurs in the presence of chronic liver injury, often as a sequela of liver fibrosis. Hepatic progenitor cells (HPCs) are known to be capable of forming both hepatocytes and cholangiocytes in chronic liver injury, which are also considered a source of myofibroblasts and tumor-initiating cells, under carcinogenic circumstances. However, the underlying mechanisms that activate HPCs to give rise to HCC are still unclear. In current study, the correlation between HPCs activation and liver fibrosis and carcinogenesis was investigated in rats and human specimens. We analyzed the role of HPCs in tumorigenesis, by transplanting exogenous HPCs in a diethylnitrosamine-induced rat HCC model. Our data indicated that HPC activation correlated with hepatic fibrosis and hepatocarcinogenesis. We further found that exogenous HPC infusion promoted liver fibrosis and hepatocarcinogenesis, while lipopolysaccharides (LPS) played an important role in this process. However, results of our study indicated that LPS did not induce HPCs to form tumor in nude mice directly. Rather, LPS induced myofibroblast-like morphology in HPCs, which enhanced the tumorigenic potential of HPCs. Further experiments showed that LPS/Toll-like receptor 4 (TLR4) signaling mediated the differentiation of HPCs into myofibroblasts and enhanced the production of interleukin-6 (IL-6) and tumor necrosis factor-α (TNF-α), which led to the aberrant expression of Ras and p53 signaling pathways in HPCs, and finally, promoted the proliferation and malignant transformation of HPCs, by long non-coding RNA regulation. Besides, examination of HCC clinical samples demonstrated that IL-6 and TNF-α production correlated with HPC activation, hepatic fibrosis, and HCC recurrence. Our study indicates that both myofibroblasts and tumor cells are derived from HPCs. HPC-derived myofibroblasts create tumor microenvironment and contribute to the proliferation and malignant transformation of HPCs. Furthermore, LPS present in the chronic liver inflammation microenvironment might play an important role in hepatocarcinogenesis, by regulating the plastic potential of HPCs.

Identification of a Novel Bone Marrow Cell-Derived Accelerator of Fibrotic Liver Regeneration Through Mobilization of Hepatic Progenitor Cells in Mice.

Granulocyte colony stimulating factor (G-CSF) has been reported to ameliorate impaired liver function in patients with advanced liver diseases through mobilization and proliferation of hepatic progenitor cells (HPCs). However, the underlying mechanisms remain unknown. We previously showed that G-CSF treatment increased the number of bone marrow (BM)-derived cells migrating to the fibrotic liver following repeated carbon tetrachloride (CCl4 ) injections into mice. In this study, we identified opioid growth factor receptor-like 1 (OGFRL1) as a novel BM cell-derived accelerator of fibrotic liver regeneration in response to G-CSF treatment. Endogenous Ogfrl1 was highly expressed in the hematopoietic organs such as the BM and spleen, whereas the liver contained a relatively small amount of Ogfrl1 mRNA. Among the peripheral blood cells, monocytes were the major sources of OGFRL1. Endogenous Ogfrl1 expression in both the peripheral blood monocytes and the liver was decreased following repeated CCl4 injections. An intrasplenic injection of cells overexpressing OGFRL1 into CCl4 -treated fibrotic mice increased the number of HPC and stimulated proliferation of hepatic parenchymal cells after partial resection of the fibrotic liver. Furthermore, overexpression of OGFRL1 in cultured HPC accelerated their differentiation as estimated by increased expression of liver-specific genes such as hepatocyte nuclear factor 4α, cytochrome P450, and fatty acid binding protein 1, although it did not affect the colony forming ability of HPC. These results indicate a critical role of OGFRL1 in the mobilization and differentiation of HPC in the fibrotic liver, and administration of OGFRL1-expressing cells may serve as a potential regenerative therapy for advanced liver fibrosis. Stem Cells 2019;37:89-101.

1α,25-dihydroxyvitamin D3 inhibits Aflatoxin B1-Induced proliferation and malignant transformation of hepatic progenitor cells by regulating PI3K/Akt and hippo pathways

Background: Hepatic progenitor cells (HPCs) might be the origin of hepatocellular carcinoma. 1α, 25-dihydroxyvitamin D3 (1, 25(OH)2D3) is capable of inhibiting the proliferation of various cancer cells . This study was conducted to determine the potential of 1α, 25(OH)2D3 to inhibit proliferation and malignant transformation of HPCs induced by aflatoxin B1 (AFB1) and explore the mechanism of inhibition. Methods: A rat HPC cell line, WB F-344 cells, were treated with AFB1, 1α, 25(OH)2D3 or combination. Cell proliferation, apoptosis, cell cycle, differentiation and invasion were measured. ICR mice were exposed to AFB1 every day for 14 d, the liver function and immunohistochemistry were surveyed. Results: AFB1 exhibited the stimulative effects on the proliferation, dedifferentiation and invasion of HPCs. In this period, the phosphorylation of AKT, expression of Yap, Taz, cyr61 and cyclin D1 were increased in cells. At the same time, phosphorylation of lats1, expression of p21 Kip1 were reduced in AFB1-treated cells. When F-344 cells were treated with AFB1 in combination with 1α, 25(OH)2D3, it was found that 1α, 25(OH)2D3 inhibited these effects of AFB1 on HPCs. Meanwhile, the expression and phosphorylation of the above pathways were reversed compared to treatment with AFB1 alone. Conclusions: These results suggest that AFB1 could induce proliferation, differentiation and transformation of HPCs, and that an enhanced 1α, 25(OH)2D3 negatively regulates the inductive effects of AFB1 on HPCs by suppressing the activation of Akt, activating Hippo pathways.