Atsunori Tsuchiya

Hepatic progenitor cells of biliary origin with liver repopulation capacity

Hepatocytes and cholangiocytes self-renew following liver injury. Following severe injury hepatocytes are increasingly senescent, but whether hepatic progenitor cells (HPCs) then contribute to liver regeneration is unclear. Here, we describe a mouse model where the E3 ubiquitin ligase Mdm2 is inducibly deleted in more than 98% of hepatocytes, causing apoptosis, necrosis and senescence with nearly all hepatocytes expressing p21. This results in florid HPC activation, which is necessary for survival, followed by complete, functional liver reconstitution. HPCs isolated from genetically normal mice, using cell surface markers, were highly expandable and phenotypically stable in vitro. These HPCs were transplanted into adult mouse livers where hepatocyte Mdm2 was repeatedly deleted, creating a non-competitive repopulation assay. Transplanted HPCs contributed significantly to restoration of liver parenchyma, regenerating hepatocytes and biliary epithelia, highlighting their in vivo lineage potency. HPCs are therefore a potential future alternative to hepatocyte or liver transplantation for liver disease.

Reduced NKG2D ligand expression in hepatocellular carcinoma correlates with early recurrence

BACKGROUND & AIMS The activating receptor natural killer group 2, member D (NKG2D) and its ligands play a crucial role in immune response to tumors. NKG2D ligand expression in tumors has been shown to be associated with tumor eradication and superior patient survival, but the involvement of NKG2D ligands in the immune response against hepatocellular carcinoma (HCC) still remains to be elucidated. METHODS We investigated the expression of NKG2D ligands in HCC tissues collected from 54 patients and HCC cell lines. We also examined the proteasome expression and the effect of inhibition of proteasome activity on NKG2D ligand expression in HCC tissues and cell lines. RESULTS In dysplastic nodules (DN), well-differentiated (well-HCC), and moderately-differentiated HCCs (mod-HCC), UL16-binding protein (ULBP) 1 was expressed predominantly in tumor cells, but not in poorly-differentiated HCCs (poor-HCC). Remarkably, recurrence-free survival of patients with ULBP1-negative HCC was significantly shorter than that of patients with ULBP1-positive HCC (p=0.006). Cox regression analysis revealed that loss of ULBP1 expression was an independent predictor of early recurrence (p=0.008). We confirmed that ULBP1 was expressed in the well- and mod-HCC cell lines, but not in the poor-HCC cell line KYN-2. However, inhibition of proteasome activity resulted in significant up-regulation of ULBP1 expression in KYN-2. Moreover, we found that 20S proteasome expression was more abundant in KYN-2 than that in the well- and mod-HCC cell lines. CONCLUSIONS ULBP1 is prevalently expressed in DN to mod-HCC, but loss of its expression correlates with tumor progression and early recurrence.

Human cord blood CD34+ cells develop into hepatocytes in the livers of NOD/SCID/γcnull mice through cell fusion

Several studies have shown that hepatocytes can be generated from hematopoietic stem cells, but this event is believed to be rare and to require hepatic damage. To investigate this phenomenon in human cells, we used a NOD/SCID/γcnull (NOG) mouse model that can achieve a tremendously high level of chimerism when transplanted with human hematopoietic cells. Even without hepatotoxic treatment other than irradiation, human albumin and α‐1‐antitrypsin‐positive cells were invariably detected in the livers of NOG mice after i.v. transplantation of human cord blood CD34+ cells. Human albumin was detected in the murine sera, indicating functional maturation of the human hepatocytes. Flow cytometric analysis of recipient liver cells in single‐cell suspension demonstrated that human albumin‐positive cells were also positive for both murine and human MHC and were negative for human CD45. PCR analysis of recipient livers revealed the expression of a wide variety of human hepatocyte‐ or cholangiocyte‐specific mRNAs. These results show that human CD34+ cells fuse with hepatocytes of NOG mice without liver injury, lose their hematopoietic phenotype, and begin hepatocyte‐specific gene transcription. These phenomena were not observed when CD34− cells were transplanted. Thus, our model revealed a previously unidentified pathway of human hematopoietic stem/progenitor cell differentiation.—Fujino, H., Hiramatsu, H., Tsuchiya, A., Niwa, A., Noma, H., Shiota, M., Umeda, K., Yoshimoto, M., Ito, M., Heike, T., Nakahata, T. Human cord blood CD34+ cells develop into hepatocytes in the livers of NOD/SCID/γcnull mice through cell fusion. FASEB J. 21, 3499–3510 (2007)

Polysialic acid/neural cell adhesion molecule modulates the formation of ductular reactions in liver injury

In severe liver injury, ductular reactions (DRs) containing bipotential hepatic progenitor cells (HPCs) branch from the portal tract. Neural cell adhesion molecule (NCAM) marks bile ducts and DRs, but not mature hepatocytes. NCAM mediates interactions between cells and surrounding matrix; however, its role in liver development and regeneration is undefined. Polysialic acid (polySia), a unique posttranslational modifier of NCAM, is produced by the enzymes, ST8SiaII and ST8SiaIV, and weakens NCAM interactions. The role of polySia with NCAM synthesizing enzymes ST8SiaII and ST8SiaIV were examined in HPCs in vivo using the choline‐deficient ethionine‐supplemented and 3,5‐diethoxycarbonyl‐1,4‐dihydrocollidine diet models of liver injury and regeneration, in vitro using models of proliferation, differentiation, and migration, and by use of mouse models with gene defects in the polysialyltransferases (St8sia 2+/−4+/−, and St8sia2−/−4−/−). We show that, during liver development, polySia is required for the correct formation of bile ducts because gene defects in both the polysialyltransferases (St8sia2+/−4+/− and St8sia2−/−4−/− mice) caused abnormal bile duct development. In normal liver, there is minimal polySia production and few ductular NCAM+ cells. Subsequent to injury, NCAM+ cells expand and polySia is produced by DRs/HPCs through ST8SiaIV. PolySia weakens cell‐cell and cell‐matrix interactions, facilitating HGF‐induced migration. Differentiation of HPCs to hepatocytes in vitro results in both transcriptional down‐regulation of polySia and cleavage of polySia‐NCAM. Cleavage of polySia by endosialidase (endoN) during liver regeneration reduces migration of DRs into parenchyma. Conclusion: PolySia modification of NCAM+ ductules weakens cell‐cell and cell‐matrix interactions, allowing DRs/HPCs to migrate for normal development and regeneration. Modulation of polySia levels may provide a therapeutic option in liver regeneration. (Hepatology 2014;60:1727–1740)

Clinicopathological analysis of CD133+ and NCAM+ human hepatic stem/progenitor cells in damaged livers and hepatocellular carcinomas

Aim:  Hepatic stem cells are capable of dramatically changing and differentiating to form mature hepatocytes in acute and chronically damaged livers; however, the clinicopathological characteristics of these heterogeneous cell populations have not been sufficiently analyzed.

Increased Susceptibility to Severe Chronic Liver Damage in CXCR4 Conditional Knock-Out Mice

BackgroundThe chemokine SDF-1 and its receptor CXCR4 are essential for the proper functioning of multiple organs. In the liver, cholangiocytes and hepatic progenitor cells (HPCs) are the main cells that produce SDF-1, and SDF-1 is thought to be essential for HPC-stimulated liver regeneration.AimsIn this study, CXCR4 conditionally targeted mice were used to analyze the role of SDF-1 in chronically damaged liver.MethodsChronic liver damage was induced in MxCre CXCR4f/null mice and the control MxCre CXCR4f/wt mice by CCl4. Serum markers were analyzed to assess liver function and damage, the number of cytokeratin-positive cells as a measure of HPCs, and the extent of liver fibrosis. Additional parameters relating to liver damage, such as markers of HPCs, liver function, MMPs, and TIMPs were measured by real-time PCR.ResultsSerum ALT was significantly higher in MxCre CXCR4f/null mice than MxCre CXCR4f/wt mice. The number of cytokeratin-positive cells and the area of fibrosis were also increased in the MxCre CXCR4f/null mice. The expression of mRNAs for several markers related to hepatic damage and regeneration was also increased in the liver of MxCre CXCR4f/null mice, including primitive HPC marker prominin-1, MMP9, TNF-α, and α-SMA.ConclusionsMxCre CXCR4f/null mice were susceptible to severe chronic liver damage, suggesting that SDF-1-CXCR4 signals are important for liver regeneration and preventing the progression of liver disease. Modulation of SDF-1 may therefore be a promising treatment strategy for patients with chronic liver disease.

Multicentric occurrence of hepatocellular carcinoma with nonalcoholic steatohepatitis

AIM To reveal the manner of hepatocellular carcinoma (HCC) development in patients with nonalcoholic steatohepatitis (NASH) focusing on multicentric occurrence (MO) of HCC. METHODS We compared clinicopathological characteristics between patients with and without MO of HCC arising from NASH background. The clinical features were implicated with reference to the literature available. RESULTS MO of HCC was identified with histological proof in 4 out of 12 patients with NASH-related HCC (2 males and 2 females). One patient had synchronous MO; an advanced HCC, two well-differentiated HCCs and a dysplastic nodule, followed by the development of metachronous MO of HCC. The other three patients had multiple advanced HCCs accompanied by a well-differentiated HCC or a dysplastic nodule. Of these three patients, one had synchronous MO, one had metachronous MO and the other had both synchronous and metachronous MO. There were no obvious differences between the patients with or without MO in terms of liver function tests, tumor markers and anatomical extent of HCC. On the other hand, all four patients with MO of HCC were older than 70 years old and had the comorbidities of obesity, type 2 diabetes mellitus (T2DM), hypertension and cirrhosis. Although these conditions were not limited to MO of HCC, all the conditions were met in only one of eight patients without MO of HCC. Thus, concurrence of these conditions may be a predisposing situation to synchronous MO of HCC. In particular, old age, T2DM and cirrhosis were suggested to be prerequisite for MO because these factors were depicted in common among two other cases with MO of HCC under NASH in the literature. CONCLUSION The putative predisposing factors and necessary preconditions for synchronous MO of HCC in NASH were suggested in this study. Further investigations are required to clarify the accurate prevalence and predictors of MO to establish better strategies for treatment and prevention leading to the prognostic improvement in NASH.

Clinical trials using mesenchymal stem cells in liver diseases and inflammatory bowel diseases

Mesenchymal stem cell (MSC) therapies have been used in clinical trials in various fields. These cells are easily expanded, show low immunogenicity, can be acquired from medical waste, and have multiple functions, suggesting their potential applications in a variety of diseases, including liver disease and inflammatory bowel disease. MSCs help prepare the microenvironment, in response to inflammatory cytokines, by producing immunoregulatory factors that modulate the progression of inflammation by affecting dendritic cells, B cells, T cells, and macrophages. MSCs also produce a large amount of cytokines, chemokines, and growth factors, including exosomes that stimulate angiogenesis, prevent apoptosis, block oxidation reactions, promote remodeling of the extracellular matrix, and induce differentiation of tissue stem cells. According to ClinicalTrials.gov, more than 680 clinical trials using MSCs are registered for cell therapy of many fields including liver diseases (more than 40 trials) and inflammatory bowel diseases (more than 20 trials). In this report, we introduce background and clinical studies of MSCs in liver disease and inflammatory bowel diseases.

A safe and effective dose of cisplatin in hepatic arterial infusion chemotherapy for hepatocellular carcinoma

Cisplatin (CDDP) is an anticancer agent that is commonly used in hepatic arterial infusion (HAI) chemotherapy for hepatocellular carcinoma (HCC). This study aimed to clarify the safe and effective dose of CDDP in HAI for HCC. The hypervascular area was measured in 42 HCCs before and after HAI with CDDP. Serum platinum concentration was quantified in the peripheral and/or middle hepatic veins by atomic absorption spectrometry. The relation between the HCC response and CDDP dose was statistically analyzed. The multiple HCC nodules in an individual case generally demonstrated the same response to CDDP. The free‐platinum concentration stayed relatively constant in the hepatic vein during HAI followed by a rapid decline, while total‐platinum gradually increased then slowly disappeared over several days. After CDDP‐HAI, 15 HCCs shrunk and 27 HCCs grew. The reduction rate in the shrunken nodules was tended to be correlated with CDDP dose after standardization with the target liver volume. On the other hand, the growth rate of the enlarged HCCs was significantly correlated with CDDP dose after normalization with creatinine clearance. These data support a recommendation of CDDP‐HAI infusion where the amount of CDDP (mg) administered is less than patient creatinine clearance (mL/min/1.73 m2) upon an assumption of HCC doubling time of 90 days, and the targeted liver is smaller than 200 times the CDDP dose (mg). A further analysis is required to define appropriate injection speeds.

Long-term efficacy and safety of nalfurafine hydrochloride on pruritus in chronic liver disease patients: Patient-reported outcome based analyses

Background and aim Among various symptoms accompanied with chronic liver disease, pruritus affects the quality of life of patients, causing physical and mental stress, and worsens hepatic function. Recently, κ-opioid receptor agonist, nalfurafine hydrochloride was approved to treat central pruritus in patients with liver disease in Japan. This study aimed to assess the long-term efficacy and safety of nalfurafine hydrochloride on pruritus in chronic liver disease patients. Methods A patient-reported outcome using questionnaire-based methods was used for 41 liver disease patients with or without pruritus symptoms. Nalfurafine hydrochloride (2.5 μg/day) was orally administered to 18 patients suffering from pruritus symptoms and whose current treatment was not effective. The same questionnaires and visual analogue scales (VAS) were repeatedly followed up for the patients for the entire follow-up period, and biochemical analyses were performed to evaluate the safety of the treatment. Results Pruritus completely disappeared in seven of 18 cases, and VAS scores showed a decreasing trend over time from the start of nalfurafine hydrochloride administration in all patients who received the medication. Among 11 patients who were followed up for more than 12 weeks, nine patients showed continuous improvement of symptoms, and this progress was still apparent at ≥20 weeks after starting administration (p < 0.0001). The medication was discontinued in four patients because of progression of primary disease, high cost, oral dryness, and anemia. No significant toxicity was observed on the serum biochemical analyses. Conclusions Nalfurafine hydrochloride contributed to long-term suppression of pruritus without significant safety problems.