Hepatocyte transplantation, a step forward?

Hepatocyte transplantation emerged a few decades ago as a possible strategy to overcome some of the limitations of liver transplantation, among them the availability of organ donors and the functional quality of grafts. Nowadays, allogenic cell transplantation is still to be confirmed as a viable therapeutic option for patients with hereditary metabolic liver diseases. Although we have now overseen 5 decades of basic and animal research in the field, the number of successfully treated patients remains low. Limitations in cell engraftment and selective proliferation of transplanted cells remain a constraint to the generalized use of this therapeutic approach

The Vitamin D Receptor Regulates Glycerolipid and Phospholipid Metabolism in Human Hepatocytes

The vitamin D receptor (VDR) must be relevant to liver lipid metabolism because VDR deficient mice are protected from hepatosteatosis. Therefore, our objective was to define the role of VDR on the overall lipid metabolism in human hepatocytes. We developed an adenoviral vector for human VDR and performed transcriptomic and metabolomic analyses of cultured human hepatocytes upon VDR activation by vitamin D (VitD). Twenty percent of the VDR responsive genes were related to lipid metabolism, including MOGAT1, LPGAT1, AGPAT2, and DGAT1 (glycerolipid metabolism); CDS1, PCTP, and MAT1A (phospholipid metabolism); and FATP2, SLC6A12, and AQP3 (uptake of fatty acids, betaine, and glycerol, respectively). They were rapidly induced (4-6 h) upon VDR activation by 10 nM VitD or 100 µM lithocholic acid (LCA). Most of these genes were also upregulated by VDR/VitD in mouse livers in vivo. Ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS) metabolomics demonstrated intracellular accumulation of triglycerides, with concomitant decreases in diglycerides and phosphatidates, at 8 and 24 h upon VDR activation. Significant alterations in phosphatidylcholines, increases in lyso-phosphatidylcholines and decreases in phosphatidylethanolamines and phosphatidylethanolamine plasmalogens were also observed. In conclusion, active VitD/VDR signaling in hepatocytes triggers an unanticipated coordinated gene response leading to triglyceride synthesis and to important perturbations in glycerolipids and phospholipids

New microRNA biomarkers for drug-induced steatosis and their potential to predict the contribution of drugs to non-alcoholic fatty liver disease

Background and Aims: Drug-induced steatosis is a major reason for drug failure in clinical trials and post-marketing withdrawal; and therefore, predictive biomarkers are essential. These could be particularly relevant in non-alcoholic fatty liver disease (NAFLD), where most patients show features of the metabolic syndrome and are prescribed with combined chronic therapies, which can contribute to fatty liver. However, specific biomarkers to assess the contribution of drugs to NAFLD are lacking. We aimed to find microRNAs (miRNAs) responsive to steatotic drugs and to investigate if they could become circulating biomarkers for drug-induced steatosis. Methods: Human HepG2 cells were treated with drugs and changes in miRNA levels were measured by microarray and qRT-PCR. Drug-induced fat accumulation in HepG2 was analyzed by high-content screening and enzymatic methods. miRNA biomarkers were also analyzed in the sera of 44 biopsy-proven NAFLD patients and in 10 controls. Results: We found a set of 10 miRNAs [miR-22-5p, -3929, -24-2-5p, -663a, -29a-3p, -21 (5p and 3p), -27a-5p, -1260 and -202-3p] that were induced in human HepG2 cells and secreted to the culture medium upon incubation with model steatotic drugs (valproate, doxycycline, cyclosporin A and tamoxifen). Moreover, cell exposure to 17 common drugs for NAFLD patients showed that some of them (e.g., irbesartan, fenofibrate, and omeprazole) also induced these miRNAs and increased intracellular triglycerides, particularly in combinations. Finally, we found that most of these miRNAs (60%) were detected in human serum, and that NAFLD patients under fibrates showed both induction of these miRNAs and a more severe steatosis grade. Conclusion: Steatotic drugs induce a common set of hepatic miRNAs that could be used in drug screening during preclinical development. Moreover, most of these miRNAs are serum circulating biomarkers that could become useful in the diagnosis of iatrogenic steatosis

SOC-V-11 New serum miRNA biomarkers to predict liver steatosis by valproic acid in paediatric epileptic patients

Depakine (Valproate, VPA) has been the first line, most-frequently prescribed, anti-epileptic drug in children for the past 50 years. Idiosyncratic hepatotoxicity (iDILI) by VPA has been demonstrated in several case reports, where microvesicular liver steatosis was the most frequent feature. Moreover, more than half of VPA-treated patients could have silent fatty liver as demonstrated by ultrasounds. Extensive experimental studies support that VPA has a high potential to induce steatosis in hepatocytes. However, there is an apparent lack of significant hepatic problems in the Neuropediatric Units, despite transaminitis is not uncommon. One of the reasons could be that iDILI and liver steatosis diagnosis lack specific biomarkers. Thus, it is likely that a relevant number of children under VPA treatment may have a significant, but sub-clinical, hepatosteatosis

Human mesenchymal stem cells from adipose tissue: Differentiation into hepatic lineage

Adipose tissue represents an accessible source of mesenchymal stem cells (ADSCs), with similar characteristics to bone marrow-derived stem cells. The aim of this work was to investigate the transdifferentiation of ADSCs into hepatic lineage cells in vitro. ADSCs were obtained from human adipose tissue from lipectomy. Cells were grown in medium containing 15% AB human serum. Cultures were serum deprived for two days and exposed to a two-step protocol with two different media using growth factors and cytokines. Hepatic differentiation was assessed by RT-PCR of liver-marker genes. ADSCs exhibited a fibroblastic morphology that changed to a cuboidal shape when cells differentiated. Expression of liver genes increased when using one of the two studied media consisting of DMEM supplemented with HGF, bFGF and nicotinamide for 14 days. The results indicate that, under certain specific inducing conditions, ADSCs can be induced to differentiate into hepatic lineage in vitro. Adipose tissue may be an ideal source of high amounts of autologous stem cells

Targeted profiling of circulating and hepatic bile acids in human, mouse, and rat using a UPLC-MRM-MS-validated method[S]

Bile acids (BAs) are a group of chemically related steroids recognized as regulatory molecules whose profiles can change in different physio-pathological situations. We have developed a sensitive, fast, and reproducible ultraperformance liquid chromatography/multiple reaction monitoring/mass spectrometry method to determine the tissue and sera BA profiles in different species (human, rat, and mouse) by quantifying 31 major and minor BA species in a single 21-min run. The method has been validated according to FDA guidelines, and it generally provides good results in terms of intra- and interday precision (less than 8.6% and 16.0%, respectively), accuracy (relative error measurement between –11.9% and 8.6%), and linearity (R2 > 0.996 and dynamic ranges between two and four orders of magnitude), with limits of quantification between 2.5 and 20 nM. The new analytical approach was applied to determine BA concentrations in human, rat, and mouse serum and in liver tissue. Our comparative study confirmed and extended previous reports, showing marked interspecies differences in circulating and hepatic BA composition. The targeted analysis revealed the presence of unexpected minoritary BAs, such as tauro-alpha-Muricholic acid in human serum, thus allowing us to obtain a thorough profiling of human samples. Its great sensitivity, low sample requirements (25 µl of serum, 5 mg of tissue), and comprehensive capacity to profile a considerable number of BAs make the present method a good choice to study BA metabolism in physiological and pathological situations, particularly in toxicological studies

Hepatogenic differentiation of human mesenchymal stem cells from adipose tissue in comparison with bone marrow mesenchymal stem cells

AIM: To investigate and compare the hepatogenic transdifferentiation of adipose tissue-derived stem cells (ADSC) and bone marrow-derived mesenchymal stem cells (BMSC) in vitro. Transdifferentiation of BMSC into hepatic cells in vivo has been described. Adipose tissue represents an accessible source of ADSC, with similar characteristics to BMSC. METHODS: BMSCs were obtained from patients undergoing total hip arthroplasty and ADSC from human adipose tissue obtained from lipectomy. Cells were grown in medium containing 15% human serum. Cultures were serum deprived for 2 d before cultivating under similar pro-hepatogenic conditions to those of liver development using a 2-step protocol with sequential addition of growth factors, cytokines and hormones. Hepatic differentiation was RT-PCR-assessed and liver-marker genes were immunohistochemically analysed. RESULTS: BMSC and ADSC exhibited a fibroblastic morphology that changed to a polygonal shape when cells differentiated. Expression of stem cell marker Thy1 decreased in differentiated ADSC and BMSC. However, the expression of the hepatic markers, albumin and CYPs increased to a similar extent in differentiated BMSC and ADSC. Hepatic gene activation could be attributed to increased liver-enriched transcription factors (C/EBPβ and HNF4α), as demonstrated by adenoviral expression vectors. CONCLUSION: Mesenchymal stem cells can be induced to hepatogenic transdifferentiation in vitro. ADSCs have a similar hepatogenic differentiation potential to BMSC, but a longer culture period and higher proliferation capacity. Therefore, adipose tissue may be an ideal source of large amounts of autologous stem cells, and may become an alternative for hepatocyte regeneration, liver cell transplantation or preclinical drug testing