N-acetylcysteine improves the viability of human hepatocytes isolated from severely steatotic donor liver tissue

Establishment of a Serum-Free Hepatocyte Cryopreservation Process for the Development of an "Off-the-Shelf" Bioartificial Liver System

To use hepatocytes immediately when necessary for hepatocyte transplantation and bioartificial liver (BAL) systems, a serum-free cryopreservation protocol ensuring the high survival of hepatocytes and maintenance of their functions should be developed. We established a serum-free protocol for the cryopreservation of primary hepatocytes, hepatocyte spheroids, and hepatocyte spheroid beads in liquid nitrogen. The serum-free cryopreservation solutions showed a significantly higher performance in maintaining enhanced viability and ammonia removal, urea secretion, and the albumin synthesis of hepatocyte spheroids and spheroid beads. The serum-free thawing medium, containing human serum albumin (HSA) and N-acetylcysteine (NAC), was compared with a fetal bovine serum-containing thawing medium for the development of a serum-free thawing medium. Our results show that hepatocyte spheroids and spheroid beads thawed using a serum-free thawing medium containing HSA and NAC exhibited increased hepatocyte viability, ammonia removal, urea secretion, and albumin synthesis compared to those thawed using the serum-containing medium. Finally, we evaluated the liver functions of the cryopreserved BAL system-applied serum-free cryopreservation process compared to the fresh BAL system. The ammonia removal efficiency of the cryopreserved hepatocyte spheroids BAL was lower than or similar to that of the fresh BAL system. Additionally, the urea concentrations in the media of all three BAL systems were not significantly different during BAL system operation. This cryopreserved spheroid-based BAL system using a serum-free process will be a good candidate for the treatment of patients.

Procurement and Evaluation of Hepatocytes for Transplantation From Neonatal Donors After Circulatory Death

Hepatocyte transplantation is a promising treatment for liver failure and inborn metabolic liver diseases, but progress has been hampered by a scarcity of available organs. Here, hepatocytes isolated from livers procured for a neonatal hepatocyte donation program within a research setting were assessed for metabolic function and suitability for transplantation. Organ donation was considered for infants who died in neonatal intensive care in the Stockholm region during 2015–2021. Inclusion was assessed when a decision to discontinue life-sustaining treatment had been made and hepatectomy performed after declaration of death. Hepatocyte isolation was performed by three-step collagenase perfusion. Hepatocyte viability, yield, and function were assessed using fresh and cryopreserved cells. Engraftment and maturation of cryopreserved neonatal hepatocytes were assessed by transplantation into an immunodeficient mouse model and analysis of the gene expression of phase I, phase II, and liver-specific enzymes and proteins. Twelve livers were procured. Median warm ischemia time (WIT) was 190 [interquartile range (IQR): 80–210] minutes. Median viability was 86% (IQR: 71%–91%). Median yield was 6.9 (IQR: 3.4–12.8) x10⁶ viable hepatocytes/g. Transplantation into immunodeficient mice resulted in good engraftment and maturation of hepatocyte-specific proteins and enzymes. A neonatal organ donation program including preterm born infants was found to be feasible. Hepatocytes isolated from neonatal donors had good viability, function, and engraftment despite prolonged WIT. Therefore, neonatal livers should be considered as a donor source for clinical hepatocyte transplantation, even in cases with extended WIT.

Cell therapy in congenital inherited hepatic disorders

Congenital inherited hepatic disorders (CIHDs) are a set of diverse and heterogeneous group of genetic disorders leading to a defect in an enzyme or transporter. Most of these disorders are currently treated by liver transplantation as standard of care. Improved surgical techniques and post-operative care has led to a wider availability and success of liver transplantation program worldwide. However liver transplantation has its own limitations due to invasive surgery and lifelong use of immunosuppressive agents. Our experience from auxiliary liver transplantation (where right or the left lobe of the patient liver is replaced with a healthy liver donor) demonstrated successful treatment of the underlying defect of noncirrhotic metabolic disorder suggesting that whole liver replacement may not be necessary to achieve a change in phenotype. Large number of animal studies in human models of CIHD have shown success of hepatocyte transplantation leading to its human use. This review addresses the current state of human hepatocyte transplantation in the management of CIHDs with bottlenecks to its wider application and future perspectives.

Stem Cell Transplant for Advanced Stage Liver Disorders: Current Scenario and Future Prospects

BACKGROUND

Chronic Liver Disorders (CLD), caused by the lifestyle patterns like alcoholism or by non-alcoholic fatty liver disease or because of virus-mediated hepatitis, affect a large population fraction across the world. CLD progresses into end-stage diseases with a high mortality rate. Liver transplant is the only approved treatment available for such end-stage disease patients. However, the number of liver transplants is limited due to the limited availability of suitable donors and the extremely high cost of performing the procedure. Under such circumstances, Stem Cell (SC) mediated liver regeneration has emerged as a potential therapeutic alternative approach.

OBJECTIVE

This review aims to critically analyze the current status and future prospects of stem cellbased interventions for end-stage liver diseases. The clinical studies undertaken, the mechanism underlying therapeutic effects and future directions have been examined.

METHOD

The clinical trial databases were searched at https://clinicaltrials.gov.in and http://www.isrctn.com to identify randomized, non-randomized and controlled studies undertaken with keywords such as "liver disorder and Mesenchymal Stem Cells (MSCs)", "liver cirrhosis and MSCs" and "liver disorder and SCs". Furthermore, https://www.ncbi.nlm.nih.gov/pubmed/ database was also explored with similar keywords for finding the available reports and their critical analyses.

RESULTS

The search results yielded a significant number of studies that used bone marrow-derived stem cells, MSCs and hepatocytes. The studies clearly indicated that SCs play a key role in the hepatoprotection process by some mechanisms involving anti-inflammation, auto-immune-suppression, angiogenesis and anti-apoptosis. Further, studies indicated that SCs derived paracrine factors promote angiogenesis, reduce inflammation and inhibit hepatocyte apoptosis.

CONCLUSION

The SC-based interventions provide a significant improvement in patients with CLD; however, there is a need for randomized, controlled studies with the analysis of a long-term follow-up.

N-Acetyl Cysteine Targets Hepatic Lipid Accumulation to Curb Oxidative Stress and Inflammation in NAFLD: A Comprehensive Analysis of the Literature

Impaired adipose tissue function and insulin resistance remain instrumental in promoting hepatic lipid accumulation in conditions of metabolic syndrome. In fact, enhanced lipid accumulation together with oxidative stress and an abnormal inflammatory response underpin the development and severity of non-alcoholic fatty liver disease (NAFLD). There are currently no specific protective drugs against NAFLD, and effective interventions involving regular exercise and healthy diets have proved difficult to achieve and maintain. Alternatively, due to its antioxidant and anti-inflammatory properties, there has been growing interest in understanding the therapeutic effects of N-acetyl cysteine (NAC) against metabolic complications, including NAFLD. Here, reviewed evidence suggests that NAC blocks hepatic lipid accumulation in preclinical models of NAFLD. This is in part through the effective regulation of a fatty acid scavenger molecule (CD36) and transcriptional factors such as sterol regulatory element-binding protein (SREBP)-1c/-2 and peroxisome proliferator-activated receptor gamma (PPARγ). Importantly, NAC appears effective in improving liver function by reducing pro-inflammatory markers such as interleukin (IL)-6 IL-1β, tumour necrosis factor alpha (TNF-α) and nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB). This was primarily through the attenuation of lipid peroxidation and enhancements in intracellular response antioxidants, particularly glutathione. Very few clinical studies support the beneficial effects of NAC against NAFLD-related complications, thus well-organized randomized clinical trials are still necessary to confirm its therapeutic potential.

Cold storage of porcine hepatocyte spheroids for spheroid bioartificial liver

BACKGROUND AND AIMS

Cell-based therapies for liver disease such as bioartificial liver rely on a large quantity and high quality of hepatocytes. Cold storage was previously shown to be a better way to preserve the viability and functionality of hepatocytes during transportation rather than freezing, but this was only proved at a lower density of rat hepatocytes spheroids. The purpose of this study was to optimize conditions for cold storage of high density of primary porcine hepatocyte spheroids.

METHODS

Porcine hepatocytes were isolated by a three-step perfusion method; hepatocyte spheroids were formed by a 24 hours rocked culture technique. Hepatocyte cell density was 5 × 10⁶ /mL in 1000 mL spheroid forming medium. Spheroids were then maintained in rocked culture at 37°C (control condition) or cold stored at 4°C for 24, 48 or 72 hours in four different cold storage solutions: histidine-tryptophan-ketoglutarate (HTK) alone; HTK + 1 mM deferoxamine (DEF); HTK + 5 mM N-acetyl-L-cysteine (NAC); and HTK + 1 mM DEF + 5 mM NAC. The viability, ammonia clearance, albumin production, gene expression, and functional activity of cytochrome P450 enzymes were measured after recovery from the cold storage.

RESULTS

In this study, we observed that cold-induced injury was reduced by the addition of the iron chelator. Viability of HTK + DEF group hepatocyte spheroids was increased compared with other cold storage groups (P < 0.05). Performance metrics of porcine hepatocyte spheroids cold stored for 24 hours were similar to those in control conditions. The hepatocyte spheroids in control conditions started to lose their ability to clear ammonia while production of albumin was still active at 48 and 72 hours (P < 0.05). In contrast, the viability and functionality of hepatocyte spheroids including ammonia clearance and albumin secretion were preserved in HTK + DEF group at both 48- and 72-hour time points (P < 0.05).

CONCLUSIONS

The beneficial effects of HTK supplemented with DEF were more obvious after cold storage of high density of porcine hepatocyte spheroids for 72 hours. The porcine hepatocyte spheroids were above the cutoff criteria for use in a spheroid-based bioartificial liver.

Hepatocyte transplantation: Consider infusion before incision

Human hepatocyte transplantation is undergoing study as a bridge, or even alternative, to orthotopic liver transplantation (OLT). This technique has undergone multiple developments over the past thirty years in terms of mode of delivery, source and preparation of cell cultures, monitoring of graft function, and use of immunosuppression. Further refinements and improvements in these techniques will likely allow improved graft survival and function, granting patients higher yield from this technique and potentially significantly delaying need for OLT.

Increased autophagic degradation contributes to the neuroprotection of hydrogen sulfide against cerebral ischemia/reperfusion injury

Hydrogen sulfide (H₂S), an endogenous gaseous signal molecule, exhibits protective effect against ischemic injury. However, its underlying mechanism is not fully understood. We have recently reported that exogenous H₂S decreases the accumulation of autophagic vacuoles in mouse brain with ischemia/reperfusion (I/R) injury. To further investigate whether this H₂S-induced reduction of autophagic vacuoles is caused by the decreased autophagosome synthesis and/or the increased autophagic degradation inautophagic flux, we performed in vitro and in vivo studies using SH-SY5Y cells for the oxygen and glucose deprivation/reoxygenation (OGD/R) and mice for the cerebral I/R, respectively. NaHS (a donor of H₂S) treatment significantly increased cell viability and reduced cerebral infarct volume. NaHS treatment reduced the OGD/R-induced elevation in LC3-II (an autophagic marker), which was completely reversed by co-treatment with an autophagic flux inhibitor bafilomycin A₁ (BafA1). However, H₂S did not affect the OGD/R-induced increase of the ULK1 self-association and decrease of the ATG13 phosphorylation, which are the critical steps for the initiation of autophagosome formation. Cerebral I/R injury caused an increase in LC3-II, a decrease in p62 and the accumulation of autophagosomes in the cortex and the hippocampus, which were inhibited by NaHS treatment. This H₂S-induced decline of LC3-II in ischemic brain was reversed by BafA1. Moreover, BafA1 treatment abolished the protection of H₂S on the cerebral infarction. Collectively, the neuroprotection of exogenous H₂S against ischemia/hypoxia and reperfusion/reoxygenation injury is mediated by the enhancement of autophagic degradation.

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.

Cellular Mechanisms of Liver Regeneration and Cell-Based Therapies of Liver Diseases

The emerging field of regenerative medicine offers innovative methods of cell therapy and tissue/organ engineering as a novel approach to liver disease treatment. The ultimate scientific foundation of both cell therapy of liver diseases and liver tissue and organ engineering is delivered by the in-depth studies of the cellular and molecular mechanisms of liver regeneration. The cellular mechanisms of the homeostatic and injury-induced liver regeneration are unique. Restoration of the mass of liver parenchyma is achieved by compensatory hypertrophy and hyperplasia of the differentiated parenchymal cells, hepatocytes, while expansion and differentiation of the resident stem/progenitor cells play a minor or negligible role. Participation of blood-borne cells of the bone marrow origin in liver parenchyma regeneration has been proven but does not exceed 1-2% of newly formed hepatocytes. Liver regeneration is activated spontaneously after injury and can be further stimulated by cell therapy with hepatocytes, hematopoietic stem cells, or mesenchymal stem cells. Further studies aimed at improving the outcomes of cell therapy of liver diseases are underway. In case of liver failure, transplantation of engineered liver can become the best option in the foreseeable future. Engineering of a transplantable liver or its major part is an enormous challenge, but rapid progress in induced pluripotency, tissue engineering, and bioprinting research shows that it may be doable.

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.

Comparison of methods for isolating primary hepatocytes from mini pigs

Successful porcine hepatocyte isolation is crucial for the development of bioartificial liver devices and hepatocyte transplantation. Serva collagenase NB grades are formulated collagenases that are suitable for various tissue isolation applications. N-acetylcysteine (NAC) can improve the viability of human hepatocytes. The aim of this study was to compare the effectiveness of two collagenases and effect of NAC on hepatocyte isolation from porcine liver tissue. Porcine hepatocytes were isolated using the perfusion method from Bama mini pigs assigned to the Serva NB 4 group (n=6), the Serva NB 8 group (n=6), or the NB 8+NAC group (n=6). Viability and yield were defined as fresh hepatocytes and their spheroids formation after 24-hour rocker culture in serum-free medium. Metabolic function was assessed by gene expression, albumin, and urea synthesis. All procedures resulted in successful hepatocyte isolation. Cells from the NB 8+NAC group had (97.8±1.9)% viability, which was higher than the NB 8 group with (94.4±2.4)% and the NB 4 group with (94.5±3.2)% (P<.001). The final cell yield reached (11.8±1.0)×10(9) cells in the NB 8+NAC group, compared to (9.5±2.1)×10(9) cells in the NB 8 group (P<.01) and (9.1±1.1) ×10(9) cells in the NB 4 group (P<.001). The secretion of albumin was superior in the NB 8+NAC group at a concentration of (425.8±35.3) ng/mL compared to the NB 8 group (339.1±32.6) ng/mL (P <.001) and NB 4 group (293.6±43.3) ng/mL (P <.01). The injury of hepatocytes also decreased in the NB 8+NAC group (P<.01). The data are presented as means ± SD. Formulated collagenase Serva NB 8 and NAC could improve the porcine hepatocyte isolation, resulting in higher yields of viable cells.

Hepatocyte cell therapy in liver disease

Liver disease is a leading cause of morbidity and mortality. Liver transplantation remains the only proven treatment for end-stage liver failure but is limited by the availability of donor organs. Hepatocyte cell therapy, either with bioartificial liver devices or hepatocyte transplantation, may help address this by delaying or preventing liver transplantation. Early clinical studies have shown promising results, however in most cases, the benefit has been short lived and so further research into these therapies is required. Alternative sources of hepatocytes, including stem cell-derived hepatocytes, are being investigated as the isolation of primary human hepatocytes is limited by the same shortage of donor organs. This review summarises the current clinical experience of hepatocyte cell therapy together with an overview of possible alternative sources of hepatocytes. Current and future areas for research that might lead towards the realisation of the full potential of hepatocyte cell therapy are discussed.

The Effect of Intraoperative N-Acetylcysteine on Hepatocellular Injury During Laparoscopic Bariatric Surgery. A Randomised Controlled Trial

BACKGROUND

The combination of pneumoperitoneum and intraoperative retraction of the left lobe of the liver leads to hepatocellular injury during laparoscopic gastric surgery. Fatty livers are more susceptible to ischaemic insults. This trial investigated whether the antioxidant N-acetylcysteine (NAC) reduced liver injury during laparoscopic sleeve gastrectomy (LSG).

METHODS

Patients undergoing LSG were randomised (single blinded) to receive intraoperative NAC infusion or standard anaesthetic treatment. Blood samples were taken before and after surgery (days 0 to 4). Primary endpoints included serum aminotransferases. Secondary measures were C-reactive protein, weight cell count (WCC), cytokines (interleukin 6 and 10) and cytokeratin-18 as markers of apoptosis. Intraoperative liver biopsy samples were assessed using a locally developed injury score.

RESULTS

Twenty patients (14 females, mean age 44.5 (SEM ± 2.9) years, mean BMI 60.8 (SEM ± 2.4) kg/m(2)) were recruited (NAC n = 10, control n = 10). The trial was stopped early after a planned interim analysis. Baseline liver function was similar. The peak rise in liver enzymes was on day 1, but levels were not significantly different between the groups. Rates of complications and length of stay were not significantly different. Secondary outcome measures, including white cell count (WCC), cytokines and cytokeratin (CK)-18 fragments, were not different between groups. Liver injury scores did not differ significantly.

CONCLUSIONS

NAC did not reduce intraoperative liver injury in this small number of patients. The heterogenous nature of the study population, with differences in co-morbidities, body mass index and intraabdominal anatomy, leads to a varied post-operative inflammatory response. Significant hepatocyte injury occurs through both necrosis and apoptosis.

Hemocyanin from Shrimp Litopenaeus vannamei Has Antiproliferative Effect against HeLa Cell In Vitro

Hemocyanin (HMC) has been shown to participate in multiple roles of immune defence. In this study, we investigated the antiproliferative effect and underpinning mechanism of HMC from Litopenaeus vannamei in vitro. Sulforhodamine B (SRB) assay indicated that HMC could dramatically inhibit the growth of HeLa cells, but not 293T cells under the same conditions. Moreover, typical morphological features of apoptosis in HeLa cells including the formation of apoptotic body-like vesicles, chromatin condensation and margination were observed by using 4, 6-diamidino-2- phenylindole dihydrochloride (DAPI) staining and fluorescence analysis. An apoptotic DNA ladder from 180 to 300 bp was also detected. Furthermore, 10 variation proteins associated with apoptosis pathway, viz. G3PDH isoforms 1/2 (G3PDH1/2), aldosereductase, ectodemal dysplasia receptor associated death receptor domain isoform CRA_a (EDARADD), heat shock 60kD protein 1 variant 1 (HSP60), heat shock 70kDa protein 5 precursor (HSP70), heat shock protein 90kDa beta member 1 precursor (HSP90), 14-3-3 protein ζ/δ, Ran and ubiquitin activating enzyme E1(UBE1), were identified from HMC-treated HeLa cells by the proteomic and quantitative real-time RT-PCR strategies. Importantly, the reactive oxygen species (ROS), mitochondrial membrane potential (Δψm) and caspase-9/3 activities were changed significantly in HMC-treated HeLa cells. Together, the data suggests that L. vannamei HMC mediates antiproliferative properties through the apoptosis mechanism involving the mitochondria triggered pathway.

Hepatocyte transplantation program: Lessons learned and future strategies

This review aims to share the lessons we learned over time during the setting of the hepatocyte transplantation (HT) program at the Hepatic Cell Therapy Unit at Hospital La Fe in Valencia. New sources of liver tissue for hepatocyte isolation have been explored. The hepatocyte isolation and cryopreservation procedures have been optimized and quality criteria for assessment of functionality of hepatocyte preparations and suitability for HT have been established. The results indicate that: (1) Only highly viable and functional hepatocytes allow to recover those functions lacking in the native liver; (2) Organs with steatosis (≥ 40%) and from elderly donors are declined since low hepatocyte yields, viability and cell survival after cryopreservation, are obtained; (3) Neonatal hepatocytes are cryopreserved without significant loss of viability or function representing high-quality cells to improve human HT; (4) Cryopreservation has the advantage of providing hepatocytes constantly available and of allowing the quality evaluation and suitability for transplantation; and (5) Our results from 5 adults with acute liver failure and 4 from children with inborn metabolic diseases, indicate that HT could be a very useful and safe cell therapy, as long as viable and metabolically functional human hepatocytes are used.

Effects of N-Acetylcysteine Addition to University of Wisconsin Solution on the Rate of Ischemia-Reperfusion Injury in Adult Orthotopic Liver Transplant

OBJECTIVES

One of the main concerns in liver transplant is the prolonged ischemia time, which may lead to primary graft nonfunction or delayed function. N-acetylcysteine is known as a hepato-protective agent in different studies, which may improve human hepatocyte viability in steatotic donor livers. This study investigated whether N-acetylcysteine can decrease the rate of ischemia-reperfusion syndrome and improve short-term outcome in liver transplant recipients.

MATERIALS AND METHODS

This was a double-blind, randomized, control clinical trial of 115 patients. Between April 2012 and January 2013, patients with orthotopic liver transplant were randomly divided into 2 groups; in 49 cases N-acetylcysteine was added to University of Wisconsin solution as the preservative liquid (experimental group), and in 66 cases standard University of Wisconsin solution was used (control group). We compared postreperfusion hypotension, inotrope requirement before and after portal reperfusion, intermittent arterial blood gas analysis and potassium measurement, pathological review of transplanted liver, in-hospital complications, morbidity, and mortality.

RESULTS

There was no significant difference between the groups regarding time to hepatic artery reperfusion, hospital stay, vascular complications, inotrope requirement before and after portal declamping, and blood gas analysis. Hypotension after portal reperfusion was significantly more common in experimental group compared with control group (P = .005). Retransplant and in-hospital mortality were comparable between the groups.

CONCLUSIONS

Preservation of the liver inside Univer-sity of Wisconsin solution plus N-acetylcysteine did not change the rate of ischemia reperfusion injury and short-term outcome in liver transplant recipients.

Cell therapy for liver disease: From liver transplantation to cell factory

Work over several decades has laid solid foundations for the advancement of liver cell therapy. To date liver cell therapy in people has taken the form of hepatocyte transplantation for metabolic disorders with a hepatic basis, and for acute or chronic liver failure. Although clinical trials using various types of autologous cells have been implemented to promote liver regeneration or reduce liver fibrosis, clear evidence of therapeutic benefits have so far been lacking. Cell types that have shown efficacy in preclinical models include hepatocytes, liver sinusoidal endothelial cells, mesenchymal stem cells, endothelial progenitor cells, and macrophages. However, positive results in animal models have not always translated through to successful clinical therapies and more realistic preclinical models need to be developed. Studies defining the optimal repopulation by transplanted cells, including routes of cell transplantation, superior engraftment and proliferation of transplanted cells, as well as optimal immunosuppression regimens are required. Tissue engineering approaches to transplant cells in extrahepatic locations have also been proposed. The derivation of hepatocytes from pluripotent or reprogrammed cells raises hope that donor organ and cell shortages could be overcome in the future. Critical hurdles to be overcome include the production of hepatocytes from pluripotent cells with equal functional capacity to primary hepatocytes and long-term phenotypic stability in vivo.

Oxidative stress triggers cytokinesis failure in hepatocytes upon isolation

Primary hepatocytes are highly differentiated cells and proliferatively quiescent. However, the stress produced during liver digestion seems to activate cell cycle entry by proliferative/dedifferentiation programs that still remain unclear. The aim of this work was to assess whether the oxidative stress associated with hepatocyte isolation affects cell cycle and particularly cytokinesis, the final step of mitosis. Hepatocytes were isolated from C57BL/6 mice by collagenase perfusion in the absence and presence of N-acetyl cysteine (NAC). Polyploidy, cell cycle, and reactive oxygen species (ROS) were studied by flow cytometry (DNA, phospho-histone 3, and CellROX(®) Deep Red) and Western blotting (cyclins B1 and D1, and proliferating cell nuclear antigen). mRNA expression of cyclins A1, B1, B2, D1, and F by reverse transcription (RT)-PCR was also assessed. Glutathione levels were measured by mass spectrometry. Here we show that hepatocyte isolation enhanced cell cycle entry, increased hepatocyte binucleation, and caused marked glutathione oxidation. Addition of 5 mM NAC to the hepatocyte isolation media prevented glutathione depletion, partially blocked ROS production and cell cycle entry of hepatocytes, and avoided the blockade of mitosis progression, abrogating defective cytokinesis and diminishing the formation of binucleated hepatocytes during isolation. Therefore, addition of NAC to the isolation media decreased the generation of polyploid hepatocytes confirming that oxidative stress occurs during hepatocyte isolation and it is responsible, at least in part, for cytokinesis failure and hepatocyte binucleation.

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.

The effect of anterograde persufflation on energy charge and hepatocyte function in donation after cardiac death livers unsuitable for transplant

Donation after cardiac death (DCD) livers are considered to be marginal organs for solid organ and cell transplantation. Low energy charge (EC) and low purine quantity within the liver parenchyma has been associated with poor outcome after liver transplantation. The aim of this work was to assess the effect of anterograde persufflation (A-PSF) using an electrochemical concentrator on DCD liver energy status and hepatocyte function. Organs utilized for research were DCD livers considered not suitable for transplant. Each liver was formally split, and the control non-persufflated (non-PSF) section was stored in University of Wisconsin (UW) solution at 4°C. The A-PSF liver section was immersed in UW solution on ice, and A-PSF was performed via the portal vein with 40% oxygen. Tissue samples were taken 2 hours after A-PSF from the A-PSF and control non-PSF liver sections for snap freezing. Purine analysis was performed with photodiode array detection. Hepatocytes were isolated from A-PSF and control non-PSF liver sections using a standard organs utilized for research were DCD livers considered not suitable for transplant collagenase perfusion technique. Hepatocyte function was assessed using mitochondrial dehydrogenase activity {3-[4,5-dimethylthiazol-2-y1]-2,5-diphenyl tetrazolium bromide (MTT)} and the sulforhodamine B (SRB) assay for cell attachment. In DCD livers with <30% steatosis (n = 6), A-PSF increased EC from 0.197 ± 0.025 to 0.23 ± 0.035 (P = 0.04). In DCD livers with >30% steatosis (n = 4), A-PSF had no beneficial effect. After isolation (n=4, <30% steatosis), A-PSF was found to increase MTT from 0.92 ± 0.045 to 1.19 ± 0.55 (P < 0.001) and SRB from 2.53 ± 0.12 to 3.2 ± 0.95 (P < 0.001). In conclusion, A-PSF can improve the EC and function of isolated hepatocytes from DCD livers with <30% steatosis.

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.

[Current status and future perspectives of hepatocyte transplantation]

The imbalance between the number of potential beneficiaries and available organs, originates the search for new therapeutic alternatives, such as Hepatocyte transplantation (HT).Even though this is a treatment option for these patients, the lack of unanimity of criteria regarding indications and technique, different cryopreservation protocols, as well as the different methodology to assess the response to this therapy, highlights the need of a Consensus Conference to standardize criteria and consider future strategies to improve the technique and optimize the results.Our aim is to review and update the current state of hepatocyte transplantation, emphasizing the future research attempting to solve the problems and improve the results of this treatment.

[Current status and future perspectives of hepatocyte transplantation]

The imbalance between the number of potential beneficiaries and available organs, originates the search for new therapeutic alternatives, such as Hepatocyte transplantation (HT).Even though this is a treatment option for these patients, the lack of unanimity of criteria regarding indications and technique, different cryopreservation protocols, as well as the different methodology to assess the response to this therapy, highlights the need of a Consensus Conference to standardize criteria and consider future strategies to improve the technique and optimize the results.Our aim is to review and update the current state of hepatocyte transplantation, emphasizing the future research attempting to solve the problems and improve the results of this treatment.

Hepatocyte isolation from unused/rejected livers for transplantation: initial step toward hepatocyte transplantation, the first experience from iran

BACKGROUND

Hepatocyte transplantation is being used in patients with liver-based metabolic disorders and acute liver failure. Hepatocytes can be isolated from unused/rejected livers under sterile conditions.

OBJECTIVES

The quality of the hepatocytes is very important and the main and initial step in hepatocyte transplantation is hepatocyte isolation. In this study we tried to set up the methods of hepatocyte isolation in order to use the high quality cells in acute liver failure or congenital metabolic disorders.

MATERIALS AND METHODS

In this study, during a year, hepatocytes were isolated from 7 unused/rejected livers among more than 300 harvested livers in Shiraz University of Medical Sciences. The two step collagenase perfusion method was used under GMP (Good manufacturing practice) for hepatocyte isolation.

RESULTS

Highly quality hepatocytes with high viability and low contamination were isolated. The mean viability was 71.8% ± 21.7. In the first 4 cases microbial contamination by Staphylococci, Diphtheroid and Klebsiella was detected, however the last 3 cases were free of any micro organisms. After 5 weeks of cryopreservation in -140°C, the cell viability was still acceptable.

CONCLUSIONS

Hepatocyte isolation can be performed as the main and initial step for cell transplantation from unused/rejected liver. It is the first experience in Iran.

Hepatocyte transplantation for inherited metabolic diseases of the liver

Inherited metabolic diseases of the liver are characterized by deficiency of a hepatic enzyme or protein often resulting in life-threatening disease. The remaining liver function is usually normal. For most patients, treatment consists of supportive therapy, and the only curative option is liver transplantation. Hepatocyte transplantation is a promising therapy for patients with inherited metabolic liver diseases, which offers a less invasive and fully reversible approach. Procedure-related complications are rare. Here, we review the experience of hepatocyte transplantation for metabolic liver diseases and discuss the major obstacles that need to be overcome to establish hepatocyte transplantation as a reliable treatment option in the clinic.

Current status of hepatocyte transplantation

Hepatocyte transplantation (HT) has been performed in patients with liver-based metabolic disease and acute liver failure as a potential alternative to liver transplantation. The results are encouraging in genetic liver conditions where HT can replace the missing enzyme or protein. However, there are limitations to the technique, which need to be overcome. Unused donor livers to isolate hepatocytes are in short supply and are often steatotic, although addition of N-acetylcysteine improves the quality of the cells obtained. Hepatocytes are cryopreserved for later use and this is detrimental to metabolic function on thawing. There are improved cryopreservation protocols, but these need further refinement. Hepatocytes are usually infused into the hepatic portal vein with many cells rapidly cleared by the innate immune system, which needs to be prevented. It is difficult to detect engraftment of donor cells in the liver, and methods to track cells labeled with iron oxide magnetic resonance imaging contrast agents are being developed. Methods to increase cell engraftment based on portal embolization or irradiation of the liver are being assessed for clinical application. Encapsulation of hepatocytes allows cells to be transplanted intraperitoneally in acute liver failure with the advantage of avoiding immunosuppression. Alternative sources of hepatocytes, which could be derived from stem cells, are needed. Mesenchymal stem cells are currently being investigated particularly for their hepatotropic effects. Other sources of cells may be better if the potential for tumor formation can be avoided. With a greater supply of hepatocytes, wider use of HT and evaluation in different liver conditions should be possible.

Steatotic liver: a suitable source for the isolation of hepatic progenitor cells

BACKGROUND

Alternative and/or complementary sources of cells such as hepatic progenitor cells (HPC) are under investigation for hepatic cell therapy purposes. Steatotic livers are those most commonly rejected for clinical transplantation and are also unsuitable for good quality hepatocyte isolation.

AIM

Taken together these two facts, our aim was to investigate whether they could represent a suitable source for the isolation of progenitor cells.

METHODS

Rats fed for 7 weeks with methionine-choline deficient diets showing proved steatotic signs (i.e. increase in hepatic lipids; macrovesicular steatosis) and steatotic and normal human liver samples were used to study the expression of HPC markers and to isolate these cells.

RESULTS

In the liver of the steatotic rats there was a significant increase in HPC (known as oval cells in rodents) markers such as Thy-1, epithelial cell adhesion molecule (EpCAM) and OV-6 (2-, 3- and 5-fold increase respectively). Additionally, there was an increase in the yield of isolated oval cells compared to control rats. Similarly, studies using human livers clearly confirmed an increase in the expression of HPC markers in the steatotic tissue and a significant rise in the number of isolated progenitor cells (EpCAM+, Thy-1+, OV-6+) (10, 12 and 11.6 × 10(4)  cells/g of tissue respectively).

CONCLUSIONS

These data suggest that steatotic livers, discarded for orthotopic liver transplantation and hepatocyte isolation, could be a suitable source for large scale isolation of HPC which might be potential candidates in liver cell therapy.

Isolation of primary human hepatocytes from normal and diseased liver tissue: a one hundred liver experience

Successful and consistent isolation of primary human hepatocytes remains a challenge for both cell-based therapeutics/transplantation and laboratory research. Several centres around the world have extensive experience in the isolation of human hepatocytes from non-diseased livers obtained from donor liver surplus to surgical requirement or at hepatic resection for tumours. These livers are an important but limited source of cells for therapy or research. The capacity to isolate cells from diseased liver tissue removed at transplantation would substantially increase availability of cells for research. However no studies comparing the outcome of human hepatocytes isolation from diseased and non-diseased livers presently exist. Here we report our experience isolating human hepatocytes from organ donors, non-diseased resected liver and cirrhotic tissue. We report the cell yields and functional qualities of cells isolated from the different types of liver and demonstrate that a single rigorous protocol allows the routine harvest of good quality primary hepatocytes from the most commonly accessible human liver tissue samples.