Isolation of primary human hepatocytes after partial hepatectomy: criteria for identification of the most promising liver specimen

ESRP1-mediated biogenesis of circPTPN12 inhibits hepatocellular carcinoma progression by PDLIM2/ NF-κB pathway

BACKGROUND

Emerging evidence indicates the pivotal involvement of circular RNAs (circRNAs) in cancer initiation and progression. Understanding the functions and underlying mechanisms of circRNAs in tumor development holds promise for uncovering novel diagnostic indicators and therapeutic targets. In this study, our focus was to elucidate the function and regulatory mechanism of hsa-circ-0003764 in hepatocellular carcinoma (HCC).

METHODS

A newly discovered hsa-circ-0003764 (circPTPN12) was identified from the circbase database. QRT-PCR analysis was utilized to assess the expression levels of hsa-circ-0003764 in both HCC tissues and cells. We conducted in vitro and in vivo experiments to examine the impact of circPTPN12 on the proliferation and apoptosis of HCC cells. Additionally, RNA-sequencing, RNA immunoprecipitation, biotin-coupled probe pull-down assays, and FISH were employed to confirm and establish the relationship between hsa-circ-0003764, PDLIM2, OTUD6B, P65, and ESRP1.

RESULTS

In HCC, the downregulation of circPTPN12 was associated with an unfavorable prognosis. CircPTPN12 exhibited suppressive effects on the proliferation of HCC cells both in vitro and in vivo. Mechanistically, RNA sequencing assays unveiled the NF-κB signaling pathway as a targeted pathway of circPTPN12. Functionally, circPTPN12 was found to interact with the PDZ domain of PDLIM2, facilitating the ubiquitination of P65. Furthermore, circPTPN12 bolstered the assembly of the PDLIM2/OTUD6B complex by promoting the deubiquitination of PDLIM2. ESRP1 was identified to bind to pre-PTPN12, thereby fostering the generation of circPTPN12.

CONCLUSIONS

Collectively, our findings indicate the involvement of circPTPN12 in modulating PDLIM2 function, influencing HCC progression. The identified ESRP1/circPTPN12/PDLIM2/NF-κB axis shows promise as a novel therapeutic target in the context of HCC.

Thymidine kinase 1 drives hepatocellular carcinoma in enzyme-dependent and -independent manners

Metabolic reprogramming plays a crucial role in the development of hepatocellular carcinoma (HCC). However, the key drivers of metabolic reprogramming underlying HCC progression remain unclear. Using a large-scale transcriptomic database and survival correlation screening, we identify thymidine kinase 1 (TK1) as a key driver. The progression of HCC is robustly mitigated by TK1 knockdown and significantly aggravated by its overexpression. Furthermore, TK1 promotes the oncogenic phenotypes of HCC not only through its enzymatic activity and production of deoxythymidine monophosphate (dTMP) but also by promoting glycolysis via binding with protein arginine methyltransferase 1 (PRMT1). Mechanistically, TK1 directly binds PRMT1 and stabilizes it by interrupting its interactions with tripartite-motif-containing 48 (TRIM48), which inhibits its ubiquitination-mediated degradation. Subsequently, we validate the therapeutic capacity of hepatic TK1 knockdown in a chemically induced HCC mouse model. Therefore, targeting both the enzyme-dependent and -independent activity of TK1 may be therapeutically promising for HCC treatment.

How Donor and Surgical Factors Affect the Viability and Functionality of Human Hepatocytes Isolated From Liver Resections

Liver resections are a significant source of primary human hepatocytes used mainly in artificial liver devices and pharmacological and biomedical studies. However, it is not well known how patient-donor and surgery-dependent factors influence isolated hepatocytes’ yield, viability, and function. Hence, we aimed to analyze the impact of all these elements on the outcome of human hepatocyte isolation.

Characterization of RNA Sensing Pathways in Hepatoma Cell Lines and Primary Human Hepatocytes

The liver is targeted by several human pathogenic RNA viruses for viral replication and dissemination; despite this, the extent of innate immune sensing of RNA viruses by human hepatocytes is insufficiently understood to date. In particular, for highly human tropic viruses such as hepatitis C virus, cell culture models are needed to study immune sensing. However, several human hepatoma cell lines have impaired RNA sensing pathways and fail to mimic innate immune responses in the human liver. Here we compare the RNA sensing properties of six human hepatoma cell lines, namely Huh-6, Huh-7, HepG2, HepG2-HFL, Hep3B, and HepaRG, with primary human hepatocytes. We show that primary liver cells sense RNA through retinoic acid-inducible gene I (RIG-I) like receptor (RLR) and Toll-like receptor 3 (TLR3) pathways. Of the tested cell lines, Hep3B cells most closely mimicked the RLR and TLR3 mediated sensing in primary hepatocytes. This was shown by the expression of RLRs and TLR3 as well as the expression and release of bioactive interferon in primary hepatocytes and Hep3B cells. Our work shows that Hep3B cells partially mimic RNA sensing in primary hepatocytes and thus can serve as in vitro model to study innate immunity to RNA viruses in hepatocytes.

Supportive Hepatocyte Transplantation after Partial Hepatectomy Enhances Liver Regeneration in a Preclinical Pig Model

BACKGROUND

Hepatocyte transplantation (HTx) is regarded as a potential treatment modality for various liver diseases including acute liver failure. We developed a preclinical pig model to evaluate if HTx could safely support recovery from liver function impairment after partial hepatectomy.

METHODS

Pigs underwent partial hepatectomy with reduction of the liver volume by 50% to induce a transient but significant impairment of liver function. Thereafter, 2 protocols for HTx were evaluated and compared to a control group receiving liver resection only (group 1, n = 5). Portal pressure-controlled HTx was performed either immediately after surgery (group 2, n = 6) or 3 days postoperatively (group 3, n = 5). In all cases, liver regeneration was monitored by conventional laboratory tests and the novel noninvasive maximum liver function capacity (LiMAx) test with a follow-up of 4 weeks.

RESULTS

Partial hepatectomy significantly impaired liver function according to conventional liver function tests as well as LiMAx in all groups. A mean of 4.10 ± 1.1 × 108 and 3.82 ± 0.7 × 108 hepatocytes were transplanted in groups 2 and 3, respectively. All animals remained stable with respect to vital parameters during and after HTx. The animals in group 2 showed enhanced liver regeneration as observed by mean postoperative LiMAx values (621.5 vs. 331.3 μg/kg/h on postoperative day 7; p < 0.001) whereas HTx in group 3 led to a significant increase in mean liver-specific coagulation factor VII (112.2 vs. 54.0% on postoperative day 7; p = 0.003) compared to controls (group 1), respectively. In both experimental groups, thrombotic material was observed in the portal veins and pulmonary arteries on histology, despite the absence of clinical symptoms.

CONCLUSION

HTx can be performed safely and effectively immediately after a partial (50%) hepatectomy as well as 3 days postoperatively, with comparable results regarding the enhancement of liver function and regeneration.

Hepatic patch by stacking patient-specific liver progenitor cell sheets formed on multiscale electrospun fibers promotes regenerative therapy for liver injury

Recently, use of cell sheets with bio-applicable fabrication materials for transplantation has been an attractive approach for the treatment of patients with liver failure. However, renewable and scalable cell sources for engineered tissue patches remain limited. We previously reported a new type of proliferating bipotent human chemically derived hepatic progenitor cells (hCdHs) developed by small molecule-mediated reprogramming. Here, we developed a patient-specific hepatic cell sheet constructed from liver biopsy-derived hCdHs on a multiscale fibrous scaffold by combining electrospinning and three-dimensional printing. Analysis of biomaterial composition revealed that the high-density electrospun sheet was superior in increasing the functional properties of hCdHs. Furthermore, the hepatic patch assembled by multilayer stacking with alternate cell sheets of hCdHs and human umbilical vein endothelial cells (HUVECs) recapitulated a liver tissue-like structure, with histological and morphological shape and size similar to those of primary human hepatocytes, and exhibited a significant increase in hepatic functions such as albumin secretion and activity of cytochrome P450 during in vitro hepatic differentiation compared with that in hCdH cells cultured in a two-dimensional monolayer. Interestingly, in the hepatic patch, the induction of functional hepatocytes was associated with both the electrospun fibrous-facilitated oncostatin M signaling and selective activation of AKT signaling by HUVECs. Notably, upon transplantation into a mouse model of therapeutic liver repopulation, the hepatic patch effectively repopulated the damaged parenchyma and induced the restoration of liver function with healthy morphology in the lobe and an improved survival rate (>70%) in mice. Overall, these results suggested that liver biopsy-derived hCdHs can be an efficient alternative source for developing hepatic cell sheets and patches with potential clinical applications in tissue engineering to advance liver regeneration.

Generation of Hepatic Progenitor Cells from the Primary Hepatocytes of Nonhuman Primates Using Small Molecules

BACKGROUND

Since primates have more biological similarities to humans than do other animals, they are a valuable resource in various field of research, including biomedicine, regenerative medicine, and drug discovery. However, there remain limitations to maintenance and expansion of primary hepatocytes derived from nonhuman primates. To overcome these limitations, we developed a novel culture system for primate cells.

METHODS

Primary hepatocytes from Macaca fascicularis (mf-PHs) were isolated from hepatectomized liver. To generate chemically derived hepatic progenitor cells (mf-CdHs), mf-PHs were cultured with reprogramming medium containing A83-01, CHIR99021, and hepatocyte growth factor (HGF). The bi-potent differentiation capacity of mf-CdHs into hepatocytes and biliary epithelial cells was confirmed by treatment with hepatic differentiation medium (HDM) and cholangiocytic differentiation medium (CDM), respectively.

RESULTS

mf-PHs cultured with reprogramming medium showed rapid proliferation capacity in vitro and expressed progenitor-specific markers. Moreover, when cultured in HDM, these progenitor cells stably differentiated into hepatocyte-like cells expressing the mature hepatic markers. On the other hand, when cultured in CDM, the differentiated biliary epithelial cells expressed mature cholangiocyte characteristics.

CONCLUSION

The results of the present study demonstrate that we successfully induced the formation of hepatic progenitor cells from mf-PHs by culturing them with a combination of small molecules, including growth factors. These results offer a means of expanding nonhuman primate hepatocytes without genetic manipulation for cellular resource, preclinical applications and regenerative medicine for the liver.

Epigenetically modulated miR-1224 suppresses the proliferation of HCC through CREB-mediated activation of YAP signaling pathway

Mounting evidence has demonstrated that microRNA-1224 (miR-1224) is commonly downregulated and serves as a tumor suppressor in multiple malignancies. However, the role and mechanisms responsible for miR-1224 in hepatocellular carcinoma (HCC) remain unclear. In this study, we found that the expression of miR-1224 was downregulated in HCC. Low miR-1224 expression was associated with poor clinicopathologic features and short overall survival. Moreover, the methylation status of putative CpG islands was also found to be an important part in the modulation of miR-1224 expression. miR-1224 could induce HCC cells to arrest in G0/G1 phase and inhibited the proliferation of HCC cells both in vitro and in vivo. Mechanistic investigation showed that by binding with cyclic AMP (cAMP)-response element binding protein (CREB) miR-1224 could repress the transcription and the activation of Yes-associated protein (YAP) signaling pathway. Furthermore, the expression of miR-1224 was inhibited by CREB through EZH2-mediated histone 3 lysine 27 (H3K27me3) on miR-1224 promoter, thus forming a positive feedback circuit. Our findings identify a miR-1224/CREB feedback loop for HCC progression and that blocking this circuit may represent a promising target for HCC treatment.

The Impact of Modern Chemotherapy and Chemotherapy-Associated Liver Injuries (CALI) on Liver Function: Value of 99mTc-Labelled-Mebrofenin SPECT-Hepatobiliary Scintigraphy

BACKGROUND

Chemotherapy is increasingly used before hepatic resection, with controversial impact regarding liver function. This study aimed to assess the capacity of 99mTc-labelled-mebrofenin SPECT-hepatobiliary scintigraphy (HBS) to predict liver dysfunction due to chemotherapy and/or chemotherapeutic-associated liver injuries (CALI), such as sinusoidal obstruction syndrome (SOS) and nonalcoholic steatohepatitis (NASH) activity score (NAS).

METHODS

From 2011 to 2015, all consecutive noncirrhotic patients scheduled for a major hepatectomy (≥ 3 segments) gave informed consent for preoperative SPECT-HBS allowing measurements of segmental liver function. As primary endpoint, HBS results were compared between patients with versus without (1) preoperative chemotherapy (≤ 3 months); and (2) CALI, mainly steatosis, NAS (Kleiner), or SOS (Rubbia-Brandt). Secondary endpoints were (1) other factors impairing function; and (2) impact of chemotherapy, and/or CALI on hepatocyte isolation outcome via liver tissues.

RESULTS

Among 115 patients, 55 (47.8%) received chemotherapy. Sixteen developed SOS and 35 NAS, with worse postoperative outcome. Overall, chemotherapy had no impact on liver function, except above 12 cycles. In patients with CALI, a steatosis ≥ 30% significantly compromised function, as well as NAS, especially grades 2-5. Conversely, SOS had no impact, although subjected to very low patients number with severe SOS. Other factors impairing function were diabetes, overweight/obesity, or fibrosis. Similarly, chemotherapy in 73 of 164 patients had no effect on hepatocytes isolation outcome; regarding CALI, steatosis ≥ 30% and NAS impaired the yield and/or viability of hepatocytes, but not SOS.

CONCLUSIONS

In this first large, prospective study, HBS appeared to be a valuable tool to select heavily treated patients at risk of liver dysfunction through steatosis or NAS.

Sofosbuvir Activates EGFR-Dependent Pathways in Hepatoma Cells with Implications for Liver-Related Pathological Processes

Direct acting antivirals (DAAs) revolutionized the therapy of chronic hepatitis C infection. However, unexpected high recurrence rates of hepatocellular carcinoma (HCC) after DAA treatment became an issue in patients with advanced cirrhosis and fibrosis. In this study, we aimed to investigate an impact of DAA treatment on the molecular changes related to HCC development and progression in hepatoma cell lines and primary human hepatocytes. We found that treatment with sofosbuvir (SOF), a backbone of DAA therapy, caused an increase in EGFR expression and phosphorylation. As a result, enhanced translocation of EGFR into the nucleus and transactivation of factors associated with cell cycle progression, B-MYB and Cyclin D1, was detected. Serine/threonine kinase profiling identified additional pathways, especially the MAPK pathway, also activated during SOF treatment. Importantly, the blocking of EGFR kinase activity by erlotinib during SOF treatment prevented all downstream events. Altogether, our findings suggest that SOF may have an impact on pathological processes in the liver via the induction of EGFR signaling. Notably, zidovudine, another nucleoside analogue, exerted a similar cell phenotype, suggesting that the observed effects may be induced by additional members of this drug class.

Alloresponses of Mixed Lymphocyte Hepatocyte Culture to Immunosuppressive Drugs as an In-Vitro Model of Hepatocyte Transplantation

Background

Hepatocyte transplantation (HCTx) has the potential for the treatment of end-stage liver disease. However, failure of engraftment and the long-term acceptance of cellular allografts remain significant challenges for its clinical application. The aim of this study was to investigate the efficacy of the immunosuppressive agents, Cyclosporine, Everolimus, and Belatacept to suppress the alloresponse of primary human hepatocytes in a mixed lymphocyte-hepatocyte culture (MLHC) and their potential hepatotoxicity in vitro.

Material/Methods

Primary human hepatocytes were co-cultured with allogeneic peripheral blood mononuclear cells (PBMCs) in an MLHC. Proliferative alloresponses were determined by flow cytometry, and cytokine secretion was measured using Luminex-based multiplex technology. Using an MLHC, the alloresponses of primary human hepatocytes were compared in the presence and absence of Cyclosporine, Everolimus, and Belatacept. Cultured primary human hepatocytes were assessed for the production of albumin, urea, aspartate transaminase (AST) and DNA content. Metabolic activity was determined with the MTT assay.

Results

Immune responses induced by primary human hepatocytes were effectively suppressed by Cyclosporine, Everolimus, and Belatacept. Everolimus significantly reduced the metabolic activity of primary human hepatocytes in vitro, suggesting impairment of cell viability. However, further functional analysis showed no significant differences between treated and untreated controls.

Conclusions

Cyclosporine, Everolimus, and Belatacept suppressed the alloresponse of primary human hepatocytes in an MLHC without significant cytotoxicity or functional cell impairment.

Long-term culture and characterization of patient-derived primary hepatocytes using conditional reprogramming

Cultivation of primary human hepatocytes (PHHs) often faces obstacles including failure of long-term in vitro culture, weak proliferation ability, rapid loss of liver-specific function and morphology, and tendency of fibrosis. Previous research focused on immortalization methods, such as telomerase and viral, to culture immortalized primary human hepatocytes, which may lose some of the normal properties. However, non-immortalized PHHs often fail to maintain long-term viability and functionality. These highlight the urgent need for developing new culture strategy for PHHs. In the present study, we isolated PHHs from fresh human liver tissues representing different liver diseases and age groups. We used conditional reprogramming, without permanent immortalization, for long-term in vitro primary human hepatocytes cultivation and characterization. For functional characterization, we assessed CYP3A4, 1A1 and 2C9 activities and measured the mRNA expression of albumin , s100a4 , krt8 , krt18 , cyp1a1 , cyp3a4 , cyp2b6 , cyp2c8 , cyp2c9 , and cyp2d6 . Additionally, we compared the DNA fingerprint of the cells against their original liver tissues using short tandem repeat (STR) analysis. We found that PHHs-derived from young patients can survive for more than three months, while the lifespan of primary human hepatocytes derived from adult patients ranges from two to three months, which is longer than most commercial primary hepatocytes. Importantly, the cells at early passages retain strong CYP3A4, 1A1 and 2C9 activities and the DNA fingerprints are identical with their original tissues. Through conditional programming, we achieved, for the first time, a high level of success rate in the long-term in vitro cultivation of primary human hepatocytes-derived patients representing diverse liver disease. Moreover, the conditional programming cell culture technology reported in this paper requires neither co-culture with additive cells, nor complex and expensive components, such as collagen sandwich or spheroid culture. We thus believe that the patient-derived PHHs cultivation using conditional programming may provide a viable and valuable cell model to study liver disease-related mechanisms.

HBV-related hepatocarcinogenesis: the role of signalling pathways and innovative ex vivo research models

BACKGROUND

Hepatitis B virus (HBV) is the leading cause of liver cancer, but the mechanisms by which HBV causes liver cancer are poorly understood and chemotherapeutic strategies to cure liver cancer are not available. A better understanding of how HBV requisitions cellular components in the liver will identify novel therapeutic targets for HBV associated hepatocellular carcinoma (HCC).

MAIN BODY

The development of HCC involves deregulation in several cellular signalling pathways including Wnt/FZD/β-catenin, PI3K/Akt/mTOR, IRS1/IGF, and Ras/Raf/MAPK. HBV is known to dysregulate several hepatocyte pathways and cell cycle regulation resulting in HCC development. A number of these HBV induced changes are also mediated through the Wnt/FZD/β-catenin pathway. The lack of a suitable human liver model for the study of HBV has hampered research into understanding pathogenesis of HBV. Primary human hepatocytes provide one option; however, these cells are prone to losing their hepatic functionality and their ability to support HBV replication. Another approach involves induced-pluripotent stem (iPS) cell-derived hepatocytes. However, iPS technology relies on retroviruses or lentiviruses for effective gene delivery and pose the risk of activating a range of oncogenes. Liver organoids developed from patient-derived liver tissues provide a significant advance in HCC research. Liver organoids retain the characteristics of their original tissue, undergo unlimited expansion, can be differentiated into mature hepatocytes and are susceptible to natural infection with HBV.

CONCLUSION

By utilizing new ex vivo techniques like liver organoids it will become possible to develop improved and personalized therapeutic approaches that will improve HCC outcomes and potentially lead to a cure for HBV.

Impact of Percoll purification on isolation of primary human hepatocytes

Research and therapeutic applications create a high demand for primary human hepatocytes. The limiting factor for their utilization is the availability of metabolically active hepatocytes in large quantities. Centrifugation through Percoll, which is commonly performed during hepatocyte isolation, has so far not been systematically evaluated in the scientific literature. 27 hepatocyte isolations were performed using a two-step perfusion technique on tissue obtained from partial liver resections. Cells were seeded with or without having undergone the centrifugation step through 25% Percoll. Cell yield, function, purity, viability and rate of bacterial contamination were assessed over a period of 6 days. Viable yield without Percoll purification was 42.4 × 10⁶ (SEM ± 4.6 × 10⁶) cells/g tissue. An average of 59% of cells were recovered after Percoll treatment. There were neither significant differences in the functional performance of cells, nor regarding presence of non-parenchymal liver cells. In five cases with initial viability of <80%, viability was significantly increased by Percoll purification (71.6 to 87.7%, p = 0.03). Considering our data and the massive cell loss due to Percoll purification, we suggest that this step can be omitted if the initial viability is high, whereas low viabilities can be improved by Percoll centrifugation.

The retinoic acid receptor (RAR) α-specific agonist Am80 (tamibarotene) and other RAR agonists potently inhibit hepatitis B virus transcription from cccDNA

Chronic infection with the human Hepatitis B virus (HBV) is a major global health problem. Hepatitis D virus (HDV) is a satellite of HBV that uses HBV envelope proteins for cell egress and entry. Using infection systems encoding the HBV/HDV receptor human sodium taurocholate co-transporting polypeptide (NTCP), we screened 1181 FDA-approved drugs applying markers for interference for HBV and HDV infection. As one primary hit we identified Acitretin, a retinoid, as an inhibitor of HBV replication and HDV release. Based on this, other retinoic acid receptor (RAR) agonists with different specificities were found to interfere with HBV replication, verifying that the retinoic acid receptor pathway regulates replication. Of the eight agonists investigated, RARα-specific agonist Am80 (tamibarotene) was most active. Am80 reduced secretion of HBeAg and HBsAg with IC₅₀s < 10 nM in differentiated HepaRG-NTCP cells. Similar effects were observed in primary human hepatocytes. In HepG2-NTCP cells, profound Am80-mediated inhibition required prolonged treatment of up to 35 days. Am80 treatment of cells with an established HBV cccDNA pool resulted in a reduction of secreted HBsAg and HBeAg, which correlated with reduced intracellular viral RNA levels, but not cccDNA copy numbers. The effect lasted for >12 days after removal of the drug. HBV genotypes B, D, and E were equally inhibited. By contrast, Am80 did not affect HBV replication in transfected cells or HepG2.2.15 cells, which carry an integrated HBV genome. In conclusion, our results indicate a persistent inhibition of HBV transcription by Am80, which might be used for drug repositioning.

Exploring donor demographics effects on hepatocyte yield and viability: Results of whole human liver isolation from one center

Due to the growth of cell-based therapeutic alternatives addressing the shortage of livers for transplant, there is necessity for a reliable source of human hepatocytes. In addition, pharmaceutical research often requires human hepatocytes to assess new drug therapies during development or to achieve FDA approval. Whole human livers producing large quantities of cells from the same donor are ideal, enhancing reproducibility for all purposes, while also allowing for capturing variances in drug-metabolism across different demographics for pharmaceutical testing and development but are limited in availability and quality for research purposes. The present study investigates the effect of donor and liver procurement factors of 16 human livers on cell viability and yield, showing that typical exclusion criteria for transplant still produce viable hepatocytes with significant yields. Although limited in number of data points, which should be taken into consideration, the conclusions of this study could be utilized as indications, allowing for expansion of liver selection criteria for hepatocyte isolation and provide the necessary quality hepatocytes in large quantities for the growing pharmaceutical, biomedical, and therapeutic research fields.

Small molecule-mediated reprogramming of human hepatocytes into bipotent progenitor cells

BACKGROUND & AIMS

Currently, much effort is directed towards the development of new cell sources for clinical therapy using cell fate conversion by small molecules. Direct lineage reprogramming to a progenitor state has been reported in terminally differentiated rodent hepatocytes, yet remains a challenge in human hepatocytes.

METHODS

Human hepatocytes were isolated from healthy and diseased donor livers and reprogrammed into progenitor cells by 2 small molecules, A83-01 and CHIR99021 (AC), in the presence of EGF and HGF. The stemness properties of human chemically derived hepatic progenitors (hCdHs) were tested by standard in vitro and in vivo assays and transcriptome profiling.

RESULTS

We developed a robust culture system for generating hCdHs with therapeutic potential. The use of HGF proved to be an essential determinant of the fate conversion process. Based on functional evidence, activation of the HGF/MET signal transduction system collaborated with A83-01 and CHIR99021 to allow a rapid expansion of progenitor cells through the activation of the ERK pathway. hCdHs expressed hepatic progenitor markers and could self-renew for at least 10 passages while retaining a normal karyotype and potential to differentiate into functional hepatocytes and biliary epithelial cells in vitro. Gene expression profiling using RNAseq confirmed the transcriptional reprogramming of hCdHs towards a progenitor state and the suppression of mature hepatocyte transcripts. Upon intrasplenic transplantation in several models of therapeutic liver repopulation, hCdHs effectively repopulated the damaged parenchyma.

CONCLUSION

Our study is the first report of successful reprogramming of human hepatocytes to a population of proliferating bipotent cells with regenerative potential. hCdHs may provide a novel tool that permits expansion and genetic manipulation of patient-specific progenitors to study regeneration and the repair of diseased livers.

LAY SUMMARY

Human primary hepatocytes were reprogrammed towards hepatic progenitor cells by a combined treatment with 2 small molecules, A83-01 and CHIR99021, and HGF. Chemically derived hepatic progenitors exhibited a high proliferation potential and the ability to differentiate into hepatocytes and biliary epithelial cells both in vitro and in vivo. This approach enables the generation of patient-specific hepatic progenitors and provides a platform for personal and stem cell-based regenerative medicine.

Hepatitis D virus replication is sensed by MDA5 and induces IFN-β/λ responses in hepatocytes

BACKGROUND & AIMS

Hepatitis B virus (HBV) and D virus (HDV) co-infections cause the most severe form of viral hepatitis. HDV induces an innate immune response, but it is unknown how the host cell senses HDV and if this defense affects HDV replication. We aim to characterize interferon (IFN) activation by HDV, identify the responsible sensor and evaluate the effect of IFN on HDV replication.

METHODS

HDV and HBV susceptible hepatoma cell lines and primary human hepatocytes (PHH) were used for infection studies. Viral markers and cellular gene expression were analyzed at different time points after infection. Pattern recognition receptors (PRRs) required for HDV-mediated IFN activation and the impact on HDV replication were studied using stable knock-down or overexpression of the PRRs.

RESULTS

Microarray analysis revealed that HDV but not HBV infection activated a broad range of interferon stimulated genes (ISGs) in HepG2^NTCP cells. HDV strongly activated IFN-β and IFN-λ in cell lines and PHH. HDV induced IFN levels remained unaltered upon RIG-I (DDX58) or TLR3 knock-down, but were almost completely abolished upon MDA5 (IFIH1) depletion. Conversely, overexpression of MDA5 but not RIG-I and TLR3 in HuH7.5^NTCP cells partially restored ISG induction. During long-term infection, IFN levels gradually diminished in both HepG2^NTCP and HepaRG^NTCP cell lines. MDA5 depletion had little effect on HDV replication despite dampening HDV-induced IFN response. Moreover, treatment with type I or type III IFNs did not abolish HDV replication.

CONCLUSION

Active replication of HDV induces an IFN-β/λ response, which is predominantly mediated by MDA5. This IFN response and exogenous IFN treatment have only a moderate effect on HDV replication in vitro indicating the adaption of HDV replication to an IFN-activated state.

LAY SUMMARY

In contrast to hepatitis B virus, infection with hepatitis D virus induces a strong IFN-β/λ response in innate immune competent cell lines. MDA5 is the key sensor for the recognition of hepatitis D virus replicative intermediates. An IFN-activated state did not prevent hepatitis D virus replication in vitro, indicating that hepatitis D virus is resistant to self-induced innate immune responses and therapeutic IFN treatment.

Comparative Analysis of Regulatory Role of Notch Signaling Pathway in 8 Types Liver Cell During Liver Regeneration

Notch signaling is closely related to cell proliferation, cell apoptosis, cell fate decisions, DNA damage repair, and so on. However, the exactly regulatory mechanism of Notch signaling pathway in liver regeneration (LR) remains unclear. To reveal the role of Notch signaling pathway in rat liver regeneration, Ingenuity Pathway Analysis (IPA) software and related pathway database were firstly used to construct the Notch signaling pathway in this study. Next, eight type cells with high purity were obtained by Percoll density centrifugation and immunomagnetic beads sorting. Then, the expression profiles of Notch signaling pathway-related genes in eight type cells were checked by using Rat Genome 230 2.0 Array, and the results showed that the expression of 42 genes were significantly regulated. H-cluster results showed that the hepatic stellate cells are attributed to one cluster; hepatocyte cell, oval cell, sinusoidal endothelial cell, and Kupffer cell are clustered together; and biliary epithelial cell, pit cell, and dendritic cell are one cluster. IPA software and Expression analysis systematic explorer analysis indicated that Notch signaling pathway-related genes were involved in cell proliferation, apoptosis, cell cycle, DNA damage repair, etc. In conclusion, Notch signaling pathway might regulate various physiological activities of LR through multiple pathways.

MiR-3662 suppresses hepatocellular carcinoma growth through inhibition of HIF-1α-mediated Warburg effect

Glucose metabolic reprogramming from oxidative to aerobic glycolysis, referred as the Warburg effect, is a hallmark of tumor cells. Accumulating evidence suggests that a subset of microRNAs play pivotal roles in modulating such reprogramming of glucose metabolism in cancer cells. miR-3662 has been implicated previously in both pro-tumorigenic and anti-tumorigenic effects in several types of cancer. The expression level of miR-3662 is downregulated in acute myeloid leukemia, whereas increased miR-3662 expression is observed in lung adenocarcinoma. However, the roles and underlying mechanisms of miR-3662 in hepatocellular carcinoma (HCC) metabolic reprogramming remain unclear. Our present study revealed that miR-3662 was frequently downregulated in HCC tissues and cell lines. The low expression level of miR-3662 was associated with tumor size, tumor multiplicity, Edmondson grade, and tumor-node-metastasis stage. Gain-of-function and loss-of-function assays showed that miR-3662 dampened glycolysis by reducing lactate production, glucose consumption, cellular glucose-6-phosphate level, ATP generation, and extracellular acidification rate, and increasing oxygen consumption rate in HCC cells after treatment with the hypoxia mimetic CoCl₂. Moreover, miR-3662 suppressed cell growth in vitro and in vivo, and induced G1/S cell cycle arrest. miR-3662 inhibited the activation of ERK and JNK signaling pathways in HCC. By combined computational and experimental approaches, hypoxia-inducible factor-1α (HIF-1α) was determined as a direct target of miR-3662. After treatment with the hypoxia mimetic CoCl₂, miR-3662 regulated the Warburg effect and HCC progression via decreasing HIF-1α expression. Our findings uncover a mechanistic role for miR-3662/HIF-1α axis in HCC metabolic reprogramming, providing a potential therapeutic strategy in liver cancer.

The Predictive Value of the Maximal Liver Function Capacity Test for the Isolation of Primary Human Hepatocytes

The need for primary human hepatocytes is constantly growing for basic research, as well as for therapeutic applications. However, the isolation outcome strongly depends on the quality of liver tissue, and we are still lacking a preoperative test that allows the prediction of the hepatocyte isolation outcome. In this study, we evaluated the "maximal liver function capacity test" (LiMAx) as predictive test for the quantitative and qualitative outcome of hepatocyte isolation. This test is already used in clinical routine to measure preoperative and to predict postoperative liver function. The patient's preoperative mean LiMAx was obtained from the patient records, and preoperative computed tomography and magnetic resonance images were used to calculate the whole liver volume to adjust the mean LiMAx. The outcome parameters of the hepatocyte isolation procedures were analyzed in correlation with the adjusted mean LiMAx. Primary human hepatocytes were isolated from partial hepatectomies (n = 64). From these 64 hepatectomies we included 48 to our study and correlated their isolation outcome parameters with volume corrected LiMAx values. From a total of 11 hepatocyte isolation procedures, metabolic parameters (albumin, urea, and aspartate aminotransferase or AST) were assessed during the hepatocyte cultivation period of 5 days. The volume adjusted mean LiMAx showed a significant positive correlation with the total cell yield (p = 0.049; r = 0.242; n = 48). The correlations of volume adjusted LiMAx values with viable cell yield and cell viability did not reach statistical significance. To create a more homogenous study group regarding tumor entities, subgroup analyses were performed. A subgroup analysis of isolations from patients with colorectal metastasis revealed a significant correlation between volume adjusted mean LiMAx and total cell yield (p = 0.012; r = 0.488; n = 21) and viable cell yield (p = 0.034; r = 0.405; n = 21), whereas a subgroup analysis of isolations of patients with carcinoma of the biliary tree showed significant correlations of volume adjusted mean LiMAx with cell viability (r = 0.387; p = 0.046; n = 20) and lacked significant correlations with total cell yield (r = -0.060; p = 0.401; n = 20) and viable cell yield (r = 0.012; p = 0.480; n = 20). The volume-adjusted mean LiMAx did not show a significant correlation with any of the metabolic parameters. In conclusion, the LiMAx test might be a useful tool to predict the quantitative outcome of hepatocyte isolation, as long as underlying liver disease is taken into consideration.

Liver 'organ on a chip'

The liver plays critical roles in both homeostasis and pathology. It is the major site of drug metabolism in the body and, as such, a common target for drug-induced toxicity and is susceptible to a wide range of diseases. In contrast to other solid organs, the liver possesses the unique ability to regenerate. The physiological importance and plasticity of this organ make it a crucial system of study to better understand human physiology, disease, and response to exogenous compounds. These aspects have impelled many to develop liver tissue systems for study in isolation outside the body. Herein, we discuss these biologically engineered organoids and microphysiological systems. These aspects have impelled many to develop liver tissue systems for study in isolation outside the body. Herein, we discuss these biologically engineered organoids and microphysiological systems.

Clinical Hepatocyte Transplantation: What Is Next?

Purpose of review

Significant recent scientific developments have occurred in the field of liver repopulation and regeneration. While techniques to facilitate liver repopulation with donor hepatocytes and different cell sources have been studied extensively in the laboratory, in recent years clinical hepatocyte transplantation (HT) and liver repopulation trials have demonstrated new disease indications and also immunological challenges that will require the incorporation of a fresh look and new experimental approaches.

Recent findings

Growth advantage and regenerative stimulus are necessary to allow donor hepatocytes to proliferate. Current research efforts focus on mechanisms of donor hepatocyte expansion in response to liver injury/preconditioning. Moreover, latest clinical evidence shows that important obstacles to HT include optimizing engraftment and limited duration of effectiveness, with hepatocytes being lost to immunological rejection. We will discuss alternatives for cellular rejection monitoring, as well as new modalities to follow cellular graft function and near-to-clinical cell sources.

Summary

HT partially corrects genetic disorders for a limited period of time and has been associated with reversal of ALF. The main identified obstacles that remain to make HT a curative approach include improving engraftment rates, and methods for monitoring cellular graft function and rejection. This review aims to discuss current state-of-the-art in clinical HT and provide insights into innovative approaches taken to overcome these obstacles.

Hepatocyte nuclear factor 4A improves hepatic differentiation of immortalized adult human hepatocytes and improves liver function and survival

Immortalized human hepatocytes (IHH) could provide an unlimited supply of hepatocytes, but insufficient differentiation and phenotypic instability restrict their clinical application. This study aimed to determine the role of hepatocyte nuclear factor 4A (HNF4A) in hepatic differentiation of IHH, and whether encapsulation of IHH overexpressing HNF4A could improve liver function and survival in rats with acute liver failure (ALF). Primary human hepatocytes were transduced with lentivirus-mediated catalytic subunit of human telomerase reverse transcriptase (hTERT) to establish IHH. Cells were analyzed for telomerase activity, proliferative capacity, hepatocyte markers, and tumorigenicity (c-myc) expression. Hepatocyte markers, hepatocellular functions, and morphology were studied in the HNF4A-overexpressing IHH. Hepatocyte markers and karyotype analysis were completed in the primary hepatocytes using shRNA knockdown of HNF4A. Nuclear translocation of β-catenin was assessed. Rat models of ALF were treated with encapsulated IHH or HNF4A-overexpressing IHH. A HNF4A-positive IHH line was established, which was non-tumorigenic and conserved properties of primary hepatocytes. HNF4A overexpression significantly enhanced mRNA levels of genes related to hepatic differentiation in IHH. Urea levels were increased by the overexpression of HNF4A, as measured 24h after ammonium chloride addition, similar to that of primary hepatocytes. Chromosomal abnormalities were observed in primary hepatocytes transfected with HNF4A shRNA. HNF4α overexpression could significantly promote β-catenin activation. Transplantation of HNF4A overexpressing IHH resulted in better liver function and survival of rats with ALF compared with IHH. HNF4A improved hepatic differentiation of IHH. Transplantation of HNF4A-overexpressing IHH could improve the liver function and survival in a rat model of ALF.

Sodium taurocholate cotransporting polypeptide is the limiting host factor of hepatitis B virus infection in macaque and pig hepatocytes

Infections with the human hepatitis B virus (HBV) and hepatitis D virus (HDV) depend on species-specific host factors like the receptor human sodium taurocholate cotransporting polypeptide (hNTCP). Complementation of mouse hepatocytes with hNTCP confers susceptibility to HDV but not HBV, indicating the requirement of additional HBV-specific factors. As an essential premise toward the establishment of an HBV-susceptible animal model, we investigated the role of hNTCP as a limiting factor of hepatocytes in commonly used laboratory animals. Primary hepatocytes from mice, rats, dogs, pigs, rhesus macaques, and cynomolgus macaques were transduced with adeno-associated viral vectors encoding hNTCP and subsequently infected with HBV. Cells were analyzed for Myrcludex B binding, taurocholate uptake, HBV covalently closed circular DNA formation, and expression of all HBV markers. Sodium taurocholate cotransporting polypeptide (Ntcp) from the respective species was cloned and analyzed for HBV and HDV receptor activity in a permissive hepatoma cell line. Expression of hNTCP in mouse, rat, and dog hepatocytes permits HDV infection but does not allow establishment of HBV infection. Contrarily, hepatocytes from cynomolgus macaques, rhesus macaques, and pigs became fully susceptible to HBV upon hNTCP expression with efficiencies comparable to human hepatocytes. Analysis of cloned Ntcp from all species revealed a pronounced role of the human homologue to support HBV and HDV infection.

CONCLUSION

Ntcp is the key host factor limiting HBV infection in cynomolgus and rhesus macaques and in pigs. In rodents (mouse, rat) and dogs, transfer of hNTCP supports viral entry but additional host factors are required for the establishment of HBV infection. This finding paves the way for the development of macaques and pigs as immunocompetent animal models to study HBV infection in vivo, immunological responses against the virus and viral pathogenesis. (Hepatology 2017;66:703-716).

Liver tissue fragments obtained from males are the most promising source of human hepatocytes for cell-based therapies - Flow cytometric analysis of albumin expression

Cell-based therapies that could provide an alternative treatment for the end-stage liver disease require an adequate source of functional hepatocytes. There is little scientific evidence for the influence of patient's age, sex, and chemotherapy on the cell isolation efficiency and metabolic activity of the harvested hepatocytes. The purpose of this study was to investigate whether hepatocytes derived from different sources display differential viability and biosynthetic capacity. Liver cells were isolated from 41 different human tissue specimens. Hepatocytes were labeled using specific antibodies and analyzed using flow cytometry. Multiparametric analysis of the acquired data revealed statistically significant differences between some studied groups of patients. Generally, populations of cells isolated from the male specimens had greater percentage of biosynthetically active hepatocytes than those from the female ones regardless of age and previous chemotherapy of the patient. Based on the albumin staining (and partially on the α-1-antitrypsin labeling) after donor liver exclusion (6 out of 41 samples), our results indicated that: 1. samples obtained from males gave a greater percentage of active hepatocytes than those from females (p = 0.034), and 2. specimens from the males after chemotherapy greater than those from the treated females (p = 0.032).

The isolation of primary hepatocytes from human tissue: optimising the use of small non-encapsulated liver resection surplus

Two-step perfusion is considered the gold standard method for isolating hepatocytes from human liver tissue. As perfusion may require a large tissue specimen, which is encapsulated and has accessible vessels for cannulation, only a limited number of tissue samples may be suitable. Therefore, the aim of this work was to develop an alternative method to isolate hepatocytes from non-encapsulated and small samples of human liver tissue. Healthy tissue from 44 human liver resections were graded for steatosis and tissue weights between 7.8 and 600 g were used for hepatocyte isolations. Tissue was diced and underwent a two-step digestion (EDTA and collagenase). Red cell lysis buffer was used to prevent red blood cell contamination and toxicity. Isolated hepatocyte viability was determined by trypan blue exclusion. Western blot and biochemical analyses were undertaken to ascertain cellular phenotype and function. Liver tissue that weighed ≥50 g yielded significantly higher (P < 0.01) cell viability than tissue <50 g. Viable cells secreted urea and displayed the phenotypic hepatocyte markers albumin and cytochrome P450. Presence of steatosis in liver tissue or intra-hepatocellular triglyceride content had no effect on cell viability. This methodology allows for the isolation of viable primary human hepatocytes from small amounts of “healthy” resected liver tissue which are not suitable for perfusion. This work provides the opportunity to increase the utilisation of resection surplus tissue, and may ultimately lead to an increased number of in vitro cellular studies being undertaken using the gold-standard model of human primary hepatocytes.

A Pathway to Personalizing Therapy for Metastases Using Liver-on-a-Chip Platforms

Metastasis accounts for most cancer-related deaths. The majority of solid cancers, including those of the breast, colorectum, prostate and skin, metastasize at significant levels to the liver due to its hemodynamic as well as tumor permissive microenvironmental properties. As this occurs prior to detection and treatment of the primary tumor, we need to target liver metastases to improve patients' outcomes. Animal models, while proven to be useful in mechanistic studies, do not represent the heterogeneity of human population especially in drug metabolism lack proper human cell-cell interactions, and this gap between animals and humans results in costly and inefficient drug discovery. This underscores the need to accurately model the human liver for disease studies and drug development. Further, the occurrence of liver metastases is influenced by the primary tumor type, sex and race; thus, modeling these specific settings will facilitate the development of personalized/targeted medicine for each specific group. We have adapted such all-human 3D ex vivo hepatic microphysiological system (MPS) (a.k.a. liver-on-a-chip) to investigate human micrometastases. This review focuses on the sources of liver resident cells, especially the iPS cell-derived hepatocytes, and examines some of the advantages and disadvantages of these sources. In addition, this review also examines other potential challenges and limitations in modeling human liver.

Isolation, characterization and cold storage of cells isolated from diseased explanted livers

INTRODUCTION

Livers discarded after standard organ retrieval are commonly used as a cell source for hepatocyte transplantation. Due to the scarcity of organ donors, this leads to a shortage of suitable cells for transplantation. Here, the isolation of liver cells from diseased livers removed during liver transplantation is studied and compared to the isolation of cells from liver specimens obtained during partial liver resection.

METHODS

Hepatocytes from 20 diseased explanted livers (Ex-group) were isolated, cultured and stored at 4°C for up to 48 hours, and compared to hepatocytes isolated from the normal liver tissue of 14 liver lobe resections (Rx-group). The nonparenchymal cell fraction (NPC) was analyzed by flow cytometry to identify potential liver progenitor cells, and OptiPrep™ (Sigma-Aldrich) density gradient centrifugation was used to enrich the progenitor cells for immediate transplantation.

RESULTS

There were no differences in viability, cell integrity and metabolic activity in cell culture and survival after cold storage when comparing the hepatocytes from the Rx-group and the Ex-group. In some cases, the latter group showed tendencies of increased resistance to isolation and storage procedures. The NPC of the Ex-group livers contained considerably more EpCAM+ and significantly more CD90+ cells than the Rx-group. Progenitor cell enrichment was not sufficient for clinical application.

CONCLUSIONS

Hepatocytes isolated from diseased explanted livers showed the essential characteristics of being adequate for cell transplantation. Increased numbers of liver progenitor cells can be isolated from diseased explanted livers. These results support the feasibility of using diseased explanted livers as a cell source for liver cell transplantation.

A Modified Protocol for the Isolation of Primary Human Hepatocytes with Improved Viability and Function from Normal and Diseased Human Liver

Successful hepatocyte isolation is critical for continued development of cellular transplantation. However, most tissue available for research is from diseased liver and the results of hepatocyte isolation from such tissue are inferior compared to normal tissue. Here we describe a modified method, combining the use of Liberase and N-acetylcysteine (NAC), for the isolation of primary human hepatocytes with high viability from normal and diseased liver.

Hepatocyte isolation from resected benign tissues: Results of a 5-year experience

AIM

To analyze retrospectively a 5-year experience of human hepatocyte isolation from resected liver tissues with benign disease.

METHODS

We established a method of modified four-step retrograde perfusion to isolate primary human hepatocytes. Samples were collected from the resected livers of patients with intrahepatic duct calculi (n = 7) and liver hemangioma (n = 17). Only the samples weighing ≥ 15 g were considered suitable for hepatocyte isolation. By using the standard trypan blue exclusion technique, hepatocyte viability and yield were immediately determined after isolation.

RESULTS

Twenty-four liver specimens, weighing 15-42 g, were immediately taken from the margin of the removed samples and transferred to the laboratory for hepatocyte isolation. Warm ischemia time was 5-35 min and cold ischemia time was 15-45 min. For the 7 samples of intrahepatic duct calculi, the method resulted in a hepatocyte yield of 3.49 ± 2.31 × 10⁶ hepatocytes/g liver, with 76.4% ± 10.7% viability. The 17 samples of liver hemangioma had significantly higher yield of cells (5.4 ± 1.71 × 10⁶ cells/g vs 3.49 ± 2.31 × 10⁶ cells/g, P < 0.05) than the samples of intrahepatic duct calculi. However, there seems to be no clear difference in cell viability (80.3% ± 9.67% vs 76.4% ± 10.7%, P > 0.05). We obtained a cell yield of 5.31 ± 1.87 × 10⁶ hepatocytes/g liver when the samples weighed > 20 g. However, for the tissues weighing ≤ 20 g, a reduction in yield was found (3.08 ± 1.86 × 10⁶ cells/g vs 5.31 ± 1.87 × 10⁶ cells/g, P < 0.05).

CONCLUSION

Benign diseased livers are valuable sources for large-number hepatocyte isolation. Our study represents the largest number of primary human hepatocytes isolated from resected specimens from patients with benign liver disease. We evaluated the effect of donor liver characteristics on cell isolation, and we found that samples of liver hemangioma can provide better results than intrahepatic duct calculi, in terms of cell yield. Furthermore, the size of the tissues can affect the outcome of hepatocyte isolation.

Human Hepatocyte Isolation: Does Portal Vein Embolization Affect the Outcome?

Primary human hepatocytes are widely used for basic research, pharmaceutical testing, and therapeutic concepts in regenerative medicine. Human hepatocytes can be isolated from resected liver tissue. Preoperative portal vein embolization (PVE) is increasingly used to decrease the risk of delayed postoperative liver regeneration by induction of selective hypertrophy of the future remnant liver tissue. The aim of this study was to investigate the effect of PVE on the outcome of hepatocyte isolation. Primary human hepatocytes were isolated from liver tissue obtained from partial hepatectomies (n = 190) using the two-step collagenase perfusion technique followed by Percoll purification. Of these hepatectomies, 27 isolations (14.2%) were performed using liver tissue obtained from patients undergoing PVE before surgery. All isolations were characterized using parameters that had been described in the literature as relevant for the outcome of hepatocyte isolation. The isolation outcomes of the PVE and the non-PVE groups were then compared before and after Percoll purification. Metabolic parameters (transaminases, urea, albumin, and vascular endothelial growth factor secretion) were measured in the supernatant of cultured hepatocytes for more than 6 days (PVE: n = 4 and non-PVE: n = 3). The PVE and non-PVE groups were similar in regard to donor parameters (sex, age, and indication for surgery), isolation parameters (liver weight and cold ischemia time), and the quality of the liver tissue. The mean initial viable cell yield did not differ between the PVE and non-PVE groups (10.16 ± 2.03 × 10(6) cells/g vs. 9.70 ± 0.73 × 10(6) cells/g, p = 0.499). The initial viability was slightly better in the PVE group (77.8% ± 2.03% vs. 74.4% ± 1.06%). The mean viable cell yield (p = 0.819) and the mean viability (p = 0.141) after Percoll purification did not differ between the groups. PVE had no effect on enzyme leakage and metabolic activity of cultured hepatocytes. Although PVE leads to drastic metabolic alterations and changes in hepatic blood flow, embolized liver tissue is a suitable source for the isolation of primary human hepatocytes and is equivalent to untreated liver tissue in regard to cell yield and viability.

Integrative proteomic and microRNA analysis of the priming phase during rat liver regeneration

The partial hepatectomy (PH) model provides an effective medium for study of liver regeneration (LR). Considering that LR is regulated by microRNAs (miRNAs), investigation of the regulatory role of miRNAs is critical for revealing how regenerative processes are initiated and controlled. Using high-throughput sequencing technology, we examined miRNA expression profiles of the regenerating rat liver after PH, and found that 23 miRNAs were related to rat LR. Among them, several miRNAs were significantly altered at 2h and 6h after PH, corresponding to the priming phase of LR. Furthermore, we examined the protein profiles in the regenerating rat liver at 2h and 6h after PH by iTRAQ coupled with LC-MS/MS, and found that 278 proteins were significantly changed. Subsequently, an integrative proteomic and microRNA analysis by Ingenuity Pathway Analysis 9.0 (IPA) software showed that miR-125a, miR-143, miR-150, miR-181c, miR-182, miR-183, miR-199a, miR-429 regulated the priming phase of rat LR by modulating the expression of proteins involved in networks critical for cell apoptosis, cell survival, cell cycle, inflammatory response, metabolism, etc. Thus, our studies provide novel evidence for a functional molecular network populated by the down-regulated targets of the up-regulated miRNAs in the priming phase of rat LR.

From whole body to cellular models of hepatic triglyceride metabolism: man has got to know his limitations

The liver is a main metabolic organ in the human body and carries out a vital role in lipid metabolism. Nonalcoholic fatty liver disease (NAFLD) is one of the most common liver diseases, encompassing a spectrum of conditions from simple fatty liver (hepatic steatosis) through to cirrhosis. Although obesity is a known risk factor for hepatic steatosis, it remains unclear what factor(s) is/are responsible for the primary event leading to retention of intrahepatocellular fat. Studying hepatic processes and the etiology and progression of disease in vivo in humans is challenging, not least as NAFLD may take years to develop. We present here a review of experimental models and approaches that have been used to assess liver triglyceride metabolism and discuss their usefulness in helping to understand the aetiology and development of NAFLD.

An algorithm that predicts the viability and the yield of human hepatocytes isolated from remnant liver pieces obtained from liver resections

Isolated human primary hepatocytes are an essential in vitro model for basic and clinical research. For successful application as a model, isolated hepatocytes need to have a good viability and be available in sufficient yield. Therefore, this study aims to identify donor characteristics, intra-operative factors, tissue processing and cell isolation parameters that affect the viability and yield of human hepatocytes. Remnant liver pieces from tissue designated as surgical waste were collected from 1034 donors with informed consent. Human hepatocytes were isolated by a two-step collagenase perfusion technique with modifications and hepatocyte yield and viability were subsequently determined. The accompanying patient data was collected and entered into a database. Univariate analyses found that the viability and the yield of hepatocytes were affected by many of the variables examined. Multivariate analyses were then carried out to confirm the factors that have a significant relationship with the viability and the yield. It was found that the viability of hepatocytes was significantly decreased by the presence of fibrosis, liver fat and with increasing gamma-glutamyltranspeptidase activity and bilirubin content. Yield was significantly decreased by the presence of liver fat, septal fibrosis, with increasing aspartate aminotransferase activity, cold ischemia times and weight of perfused liver. However, yield was significantly increased by chemotherapy treatment. In conclusion, this study determined the variables that have a significant effect on the viability and the yield of isolated human hepatocytes. These variables have been used to generate an algorithm that can calculate projected viability and yield of isolated human hepatocytes. In this way, projected viability can be determined even before isolation of hepatocytes, so that donors that result in high viability and yield can be identified. Further, if the viability and yield of the isolated hepatocytes is lower than expected, this will highlight a methodological problem that can be addressed.

Species-specific regulation of fibrinogen synthesis with implications for porcine hepatocyte xenotransplantation

BACKGROUND

Patients with liver failure could potentially be bridged with porcine xenogeneic liver cell transplantation. We examined species-specific differences between primary human and porcine hepatocytes in the regulation of coagulation protein expression and function.

METHODS

Isolated primary human and porcine hepatocytes were stimulated with either porcine or human interleukin (IL)-6 (10 ng/ml), IL-1β (10 ng/ml), and tumor necrosis factor-alpha (TNF-α, 30 ng/ml). mRNA expression of coagulation factors were measured by RT-PCR and real-time PCR. Cell culture supernatants were used for the measurement of fibrinogen by ELISA and determination of fibrin clot generation.

RESULTS

Fibrinogen expression in human hepatocytes increased after IL-6 treatment (P = 0.010) and decreased after TNF-α treatment (P = 0.005). Porcine hepatocytes displayed a lower increase in fibrinogen expression after IL-6 treatment as compared to hepatocytes of human origin (P = 0.021). Porcine hepatocytes responded contrarily following TNF-α treatment with an increased expression of fibrinogen resulting in a significant species-specific difference between human and porcine hepatocytes (P = 0.029). Fibrin polymer generation by human hepatocytes was stable and widely branched after IL-6 treatment, while stimulation with TNF-α displayed no fibrin generation at all. In contrast, treatment of porcine hepatocytes with TNF-α resulted in generation of a stable and widely branched fibrin polymer, and stimulation with IL-6 only leads to generation of partial fibrin aggregates.

CONCLUSION

We identified species-specific differences in the regulation of fibrinogen mRNA expression and fibrin generation under inflammatory stimuli. In hepatic xenotransplantation of porcine origin, these interspecies differences might lead to a loss of physiological coagulation function and a loss of transplanted cells.

Explanted diseased livers - a possible source of metabolic competent primary human hepatocytes

Being an integral part of basic, translational and clinical research, the demand for primary human hepatocytes (PHH) is continuously growing while the availability of tissue resection material for the isolation of metabolically competent PHH remains limited. To overcome current shortcomings, this study evaluated the use of explanted diseased organs from liver transplantation patients as a potential source of PHH. Therefore, PHH were isolated from resected surgical specimens (Rx-group; n = 60) and explanted diseased livers obtained from graft recipients with low labMELD-score (Ex-group; n = 5). Using established protocols PHH were subsequently cultured for a period of 7 days. The viability and metabolic competence of cultured PHH was assessed by the following parameters: morphology and cell count (CyQuant assay), albumin synthesis, urea production, AST-leakage, and phase I and II metabolism. Both groups were compared in terms of cell yield and metabolic function, and results were correlated with clinical parameters of tissue donors. Notably, cellular yields and viabilities were comparable between the Rx- and Ex-group and were 5.3±0.5 and 2.9±0.7×10⁶ cells/g liver tissue with 84.3±1.3 and 76.0±8.6% viability, respectively. Moreover, PHH isolated from the Rx- or Ex-group did not differ in regards to loss of cell number in culture, albumin synthesis, urea production, AST-leakage, and phase I and II metabolism (measured by the 7-ethoxycoumarin-O-deethylase and uracil-5′-diphosphate-glucuronyltransferase activity). Likewise, basal transcript expressions of the CYP monooxygenases 1A1, 2C8 and 3A4 were comparable as was their induction when treated with a cocktail that consisted of 3-methylcholantren, rifampicin and phenobarbital, with increased expression of CYP 1A1 and 3A4 mRNA while transcript expression of CYP 2C8 was only marginally changed. In conclusion, the use of explanted diseased livers obtained from recipients with low labMELD-score might represent a valuable source of metabolically competent PHH which are comparable in viability and function to cells obtained from specimens following partial liver resection.

Study on the activity of the signaling pathways regulating hepatocytes from G0 phase into G1 phase during rat liver regeneration

Under normal physiological conditions, the majority of hepatocytes are in the functional state (G0 phase). After injury or liver partial hepatectomy (PH), hepatocytes are rapidly activated to divide. To understand the mechanism underlying hepatocyte G0/G1 transition during rat liver regeneration, we used the Rat Genome 230 2.0 Array to determine the expression changes of genes, then searched the GO and NCBI databases for genes associated with the G0/G1 transition, and QIAGEN and KEGG databases for the G0/G1 transition signaling pathways. We used expression profile function (E t ) to calculate the activity level of the known G0/G1 transition signal pathways, and Ingenuity Pathway Analysis 9.0 (IPA) to determine the interactions among these signaling pathways. The results of our study show that the activity of the signaling pathways of HGF, IL-10 mediated by p38MAPK, IL-6 mediated by STAT3, and JAK/STAT mediated by Ras/ERK and STAT3 are significantly increased during the priming phase (2-6 h after PH) of rat liver regeneration. This leads us to conclude that during rat liver regeneration, the HGF, IL-10, IL-6 and JAK/STAT signaling pathways play a major role in promoting hepatocyte G0/G1 transition in the regenerating liver.

Inhibition of autophagic flux by salinomycin results in anti-cancer effect in hepatocellular carcinoma cells

Salinomycin raised hope to be effective in anti-cancer therapies due to its capability to overcome apoptosis-resistance in several types of cancer cells. Recently, its effectiveness against human hepatocellular carcinoma (HCC) cells both in vitro and in vivo was demonstrated. However, the mechanism of action remained unclear. Latest studies implicated interference with the degradation pathway of autophagy. This study aimed to determine the impact of Salinomycin on HCC-autophagy and whether primary human hepatocytes (PHH) likewise are affected. Following exposure of HCC cell lines HepG2 and Huh7 to varying concentrations of Salinomycin (0-10 µM), comprehensive analysis of autophagic activity using western-blotting and flow-cytometry was performed. Drug effects were analyzed in the settings of autophagy stimulation by starvation or PP242-treatment and correlated with cell viability, proliferation, apoptosis induction, mitochondrial mass accumulation and reactive oxygen species (ROS) formation. Impact on apoptosis induction and cell function of PHH was analyzed. Constitutive and stimulated autophagic activities both were effectively suppressed in HCC by Salinomycin. This inhibition was associated with dysfunctional mitochondria accumulation, increased apoptosis and decreased proliferation and cell viability. Effects of Salinomycin were dose and time dependent and could readily be replicated by pharmacological and genetic inhibition of HCC-autophagy alone. Salinomycin exposure to PHH resulted in transient impairment of synthesis function and cell viability without apoptosis induction. In conclusion, our data suggest that Salinomycin suppresses late stages of HCC-autophagy, leading to impaired recycling and accumulation of dysfunctional mitochondria with increased ROS-production all of which are associated with induction of apoptosis.

The clinically approved drugs amiodarone, dronedarone and verapamil inhibit filovirus cell entry

Objectives

Filoviruses such as Ebola virus and Marburg virus cause a severe haemorrhagic fever syndrome in humans for which there is no specific treatment. Since filoviruses use a complex route of cell entry that depends on numerous cellular factors, we hypothesized that there may be drugs already approved for human use for other indications that interfere with signal transduction or other cellular processes required for their entry and hence have anti-filoviral properties.

Methods

We used authentic filoviruses and lentiviral particles pseudotyped with filoviral glycoproteins to identify and characterize such compounds.

Results

We discovered that amiodarone, a multi-ion channel inhibitor and adrenoceptor antagonist, is a potent inhibitor of filovirus cell entry at concentrations that are routinely reached in human serum during anti-arrhythmic therapy. A similar effect was observed with the amiodarone-related agent dronedarone and the L-type calcium channel blocker verapamil. Inhibition by amiodarone was concentration dependent and similarly affected pseudoviruses as well as authentic filoviruses. Inhibition of filovirus entry was observed with most but not all cell types tested and was accentuated by the pre-treatment of cells, indicating a host cell-directed mechanism of action. The New World arenavirus Guanarito was also inhibited by amiodarone while the Old World arenavirus Lassa and members of the Rhabdoviridae (vesicular stomatitis virus) and Bunyaviridae (Hantaan) families were largely resistant.

Conclusions

The ion channel blockers amiodarone, dronedarone and verapamil inhibit filoviral cell entry.

An extended ΔCT-method facilitating normalisation with multiple reference genes suited for quantitative RT-PCR analyses of human hepatocyte-like cells

Reference genes (RG) as sample internal controls for gene transcript level analyses by quantitative RT-PCR (RT-qPCR) must be stably expressed within the experimental range. A variety of in vitro cell culture settings with primary human hepatocytes, and Huh-7 and HepG2 cell lines, were used to determine candidate RG expression stability in RT-qPCR analyses. Employing GeNorm, BestKeeper and Normfinder algorithms, this study identifies PSMB6, MDH1 and some more RG as sufficiently unregulated, thus expressed at stable levels, in hepatocyte-like cells in vitro. Inclusion of multiple RG, quenching occasional regulations of single RG, greatly stabilises gene expression level calculations from RT-qPCR data. To further enhance validity and reproducibility of relative RT-qPCR quantifications, the ΔCT calculation can be extended (e-ΔCT) by replacing the CT of a single RG in ΔCT with an averaged CT-value from multiple RG. The use of two or three RG - here identified suited for human hepatocyte-like cells - for normalisation with the straightforward e-ΔCT calculation, should improve reproducibility and robustness of comparative RT-qPCR-based gene expression analyses.

Combined use of N-acetylcysteine and Liberase improves the viability and metabolic function of human hepatocytes isolated from human liver

Background aims

Successful hepatocyte isolation is critical for continued development of cellular transplantation. However, most tissue available for research is from diseased liver, and the results of hepatocyte isolation from such tissue are inferior compared with normal tissue. Liberase and N-acetylcysteine (NAC) have been shown separately to improve viability of isolated hepatocytes. This study aims to determine the effect of Liberase and NAC in combination on human hepatocyte isolation from normal and diseased liver tissues.

Methods

Hepatocytes were isolated from 30 liver specimens through the use of a standard collagenase digestion technique (original protocol) and another 30 with the addition of NAC and standard collagenase substituted by Liberase (new protocol). Viability and success, defined as maintenance of cell adhesion and morphology for 48 hours, were assessed. Metabolic function was assessed by means of albumin and urea synthesis.

Results

Baseline factors were similar for both groups. The delay to tissue processing was slightly shorter in the new protocol group (median, 2 versus 4 hours; P = 0.007). The success rate improved from 12 of 30 (40.0%) to 21 of 30 (70.0%) with the use of the new protocol (P = 0.037), and median viable cell yield increased from 7.3 × 10⁴ to 28.3 × 10⁴ cells/g tissue (P = 0.003). After adjusting for delay, success rate (P = 0.014) and viable cell yield/g tissue (P = 0.001) remained significantly improved. Albumin and urea synthesis were similar or superior in the new protocol group.

Conclusions

NAC and Liberase improve the success of hepatocyte isolation, with a significantly higher yield of viable cells. The use of these agents may improve the availability of hepatocytes for transplantation and laboratory research.

Exchange of cytosolic content between T cells and tumor cells activates CD4 T cells and impedes cancer growth

BACKGROUND

T cells are known to participate in the response to tumor cells and react with cytotoxicity and cytokine release. At the same time tumors established versatile mechanisms for silencing the immune responses. The interplay is far from being completely understood. In this study we show contacts between tumor cells and lymphocytes revealing novel characteristics in the interaction of T cells and cancer cells in a way not previously described.

METHODS/ FINDINGS

Experiments are based on the usage of a hydrophilic fluorescent dye that occurs free in the cytosol and thus transfer of fluorescent cytosol from one cell to the other can be observed using flow cytometry. Tumor cells from cell lines of different origin or primary hepatocellular carcinoma (HCC) cells were incubated with lymphocytes from human and mice. This exposure provoked a contact dependent uptake of tumor derived cytosol by lymphocytes--even in CD4⁺ T cells and murine B cells--which could not be detected after incubation of lymphocytes with healthy cells. The interaction was a direct one, not requiring the presence of accessory cells, but independent of cytotoxicity and TCR engagement. Electron microscopy disclosed 100-200 nm large gaps in the cell membranes of connected cells which separated viable and revealed astonishing outcome. While the lymphocytes were induced to proliferate in a long term fashion, the tumor cells underwent a temporary break in cell division. The in vitro results were confirmed in vivo using a murine acute lymphoblastic leukemia (ALL) model. The arrest of tumor proliferation resulted in a significant prolonged survival of challenged mice.

CONCLUSIONS

The reported cell-cell contacts reveal new characteristics i.e. the enabling of cytosol flow between the cells including biological active proteins that influence the cell cycle and biological behaviour of the recipient cells. This adds a completely new aspect in tumor induced immunology.

Functional 3D human primary hepatocyte spheroids made by co-culturing hepatocytes from partial hepatectomy specimens and human adipose-derived stem cells

We have generated human hepatocyte spheroids with uniform size and shape by co-culturing 1∶1 mixtures of primary human hepatocytes (hHeps) from partial hepatectomy specimens and human adipose-derived stem cells (hADSCs) in concave microwells. The hADSCs in spheroids could compensate for the low viability and improve the functional maintenance of hHeps. Co-cultured spheroids aggregated and formed compact spheroidal shapes more rapidly, and with a significantly higher viability than mono-cultured spheroids. The liver-specific functions of co-cultured spheroids were greater, although they contained half the number of hepatocytes as mono-cultured spheroids. Albumin secretion by co-cultured spheroids was 10% higher on day 7, whereas urea secretion was similar, compared with mono-cultured spheroids. A quantitative cytochrome P450 assay showed that the enzymatic activity of co-cultured spheroids cultured for 9 days was 28% higher than that of mono-cultured spheroids. These effects may be due to the transdifferentiation potential and paracrine healing effects of hADSCs on hHeps. These co-cultured spheroids may be useful for creating artificial three-dimensional hepatic tissue constructs and for cell therapy with limited numbers of human hepatocytes.