Hepatocyte isolation and transplantation in the pig

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.

Direct conversion of porcine primary fibroblasts into hepatocyte-like cells

The pig is an important model organism for biomedical research, mainly due to its extensive genetic, physiological and anatomical similarities with humans. Until date, direct conversion of somatic cells into hepatocyte-like cells (iHeps) has only been achieved in rodents and human cells. Here, we employed lentiviral vectors to screen a panel of 12 hepatic transcription factors (TF) for their potential to convert porcine fibroblasts into hepatocyte-like cells. We demonstrate for the first time, hepatic conversion of porcine somatic cells by over-expression of CEBPα, FOXA1 and HNF4α2 (3TF-piHeps). Reprogrammed 3TF-piHeps display a hepatocyte-like morphology and show functional characteristics of hepatic cells, including albumin secretion, Dil-AcLDL uptake, storage of lipids and glycogen and activity of cytochrome P450 enzymes CYP1A2 and CYP2C33 (CYP2C9 in humans). Moreover, we show that markers of mature hepatocytes are highly expressed in 3TF-piHeps, while fibroblastic markers are reduced. We envision piHeps as useful cell sources for future studies on drug metabolism and toxicity as well as in vitro models for investigation of pig-to-human infectious diseases.

End-stage liver failure: filling the treatment gap at the intensive care unit

End-stage liver failure is a condition of collapsing liver function with mortality rates up to 80. Liver transplantation is the only lifesaving therapy. There is an unmet need for therapy to extend the waiting time for liver transplantation or regeneration of the native liver. Here we review the state-of-the-art of non-cell based and cell-based artificial liver support systems, cell transplantation and plasma exchange, with the first therapy relying on detoxification, while the others aim to correct also other failing liver functions and/or modulate the immune response. Meta-analyses on the effect of non-cell based systems show contradictory outcomes for different types of albumin purification devices. For bioartificial livers proof of concept has been shown in animals with liver failure. However, large clinical trials with two different systems did not show a survival benefit. Two clinical trials with plasma exchange and one with transplantation of mesenchymal stem cells showed positive outcomes on survival. Detoxification therapies lack adequacy for most patients. Correction of additional liver functions, and also modulation of the immune system hold promise for future therapy of liver failure.

miR-885-5p Negatively Regulates Warburg Effect by Silencing Hexokinase 2 in Liver Cancer

Growing tumor cells possess a distinct metabolic phenomenon that allows them to preferentially utilize glucose through aerobic glycolysis, which is referred to as the “Warburg effect.” Accumulating evidence suggests that microRNAs (miRNAs) could regulate such metabolic reprogramming. Our microarray analysis and quantitative real-time PCR validation revealed that miR-885-5p was strongly downregulated in hepatocellular carcinoma (HCC) tissues and cell lines. To investigate miR-885-5p’s biological functions in HCC progression, malignant phenotypes were analyzed in different types of hypoxic model and indicated that overexpression of miR-885-5p significantly inhibited HCC cell proliferation and migration and induced apoptosis in vitro and tumor growth in vivo. Subsequent investigations of whether miR-885-5p regulated the glycometabolic activity of cancer cells demonstrated that forced expression of miR-885-5p in SMMC-7721 cells significantly reduced glucose uptake and lactate production by repressing several key enzymes related to glycolysis. Particularly, miR-885-5p directly targets the 3′ UTR of hexokinase 2 (HK2), which is a key enzyme that catalyzes the irreversible first step of glycolysis and associates with poor patient outcomes. The miR-885-5p/HK2 axis strongly links aerobic glycolysis to carcinogenesis and may become a promising therapeutic target and prognostic predictor for HCC patients.

Cytokines in adipose-derived mesenchymal stem cells promote the healing of liver disease

Adipose-derived mesenchymal stem cells (ADSCs) are a treatment cell source for patients with chronic liver injury. ADSCs are characterized by being harvested from the patient's own subcutaneous adipose tissue, a high cell yield (i.e., reduced immune rejection response), accumulation at a disease nidus, suppression of excessive immune response, production of various growth factors and cytokines, angiogenic effects, anti-apoptotic effects, and control of immune cells via cell-cell interaction. We previously showed that conditioned medium of ADSCs promoted hepatocyte proliferation and improved the liver function in a mouse model of acute liver failure. Furthermore, as found by many other groups, the administration of ADSCs improved liver tissue fibrosis in a mouse model of liver cirrhosis. A comprehensive protein expression analysis by liquid chromatography with tandem mass spectrometry showed that the various cytokines and chemokines produced by ADSCs promote the healing of liver disease. In this review, we examine the ability of expressed protein components of ADSCs to promote healing in cell therapy for liver disease. Previous studies demonstrated that ADSCs are a treatment cell source for patients with chronic liver injury. This review describes the various cytokines and chemokines produced by ADSCs that promote the healing of liver disease.

Preparation and Characterization of Alginate-Chitosan Microcapsule for Hepatocyte Culture

This method is used to prepare microencapsulation of hepatocytes. The key steps in the protocol are (a) isolation of porcine hepatocytes, followed by (b) production of hepatocytes encapsulation, and (c) evaluation of encapsulations and hepatocytes. This method of collecting porcine hepatocytes was first used in 2003 (Maruyama et al. Cell Transplant 12:593-598, 2003). Cell encapsulation technology was first introduced by Chang (Science 146:524-525, 1964) and later by Lim and Sun in 1980 (Science 210:908-910, 1980). Since then, it has been well adopted in tissue engineering and controlled delivery of biological therapeutics such as bioartificial liver.

Magnetic cell labeling of primary and stem cell-derived pig hepatocytes for MRI-based cell tracking of hepatocyte transplantation

Pig hepatocytes are an important investigational tool for optimizing hepatocyte transplantation schemes in both allogeneic and xenogeneic transplant scenarios. MRI can be used to serially monitor the transplanted cells, but only if the hepatocytes can be labeled with a magnetic particle. In this work, we describe culture conditions for magnetic cell labeling of cells from two different pig hepatocyte cell sources; primary pig hepatocytes (ppHEP) and stem cell-derived hepatocytes (PICM-19FF). The magnetic particle is a micron-sized iron oxide particle (MPIO) that has been extensively studied for magnetic cell labeling for MRI-based cell tracking. ppHEP could endocytose MPIO with labeling percentages as high as 70%, achieving iron content as high as ~55 pg/cell, with >75% viability. PICM-19FF had labeling >97%, achieving iron content ~38 pg/cell, with viability >99%. Extensive morphological and functional assays indicated that magnetic cell labeling was benign to the cells. The results encourage the use of MRI-based cell tracking for the development and clinical use of hepatocyte transplantation methodologies. Further, these results generally highlight the importance of functional cell assays in the evaluation of contrast agent biocompatibility.

IFN-γ regulates cytochrome 3A29 through pregnane X receptor in pigs

1. The expression and the activity of cytochromes P450 (CYPs) can be elevated by the activation of nuclear receptors. The pregnane X receptor (PXR, or nuclear receptor NR1I2) is a ligand-activated transcription factor that mediates responses to diverse xenobiotics and endogenous chemicals. Here we investigated the regulatory role of PXR in IFN-γ-mediated CYP3A29 expression in pig liver microsomes, primary porcine hepatocytes, and a cultured hepatocyte cell line. 2. IFN-γ significantly up-regulated CYP3A29 and PXR expressions at mRNA and protein levels in a dose-dependent manner. IFN-γ treatment significantly increased the metabolism of nifedipine. PXR and IFN-γ treatments significantly enhanced the activity of CYP3A29 promoter and the upstream region from -1473 to -1021 of CYP3A29 might be PXR-binding site. Moreover, the IFN-γ-induced CYP3A29 expression was blocked by PXR knockdown, whereas CYP3A29 mRNA and protein expression levels were dramatically elevated by PXR overexpression. 3. The regulatory effect of IFN-γ on CYP3A29 expression is mediated via PXR.

Human-scale whole-organ bioengineering for liver transplantation: a regenerative medicine approach

At this time, the only definitive treatment of hepatic failure is liver transplantation. However, transplantation has been limited by the severely limited supply of human donor livers. Alternatively, a regenerative medicine approach has been recently proposed in rodents that describe the production of three-dimensional whole-organ scaffolds for assembly of engineered complete organs. In the present study, we describe the decellularization of porcine livers to generate liver constructs at a scale that can be clinically relevant. Adult ischemic porcine livers were successfully decellularized using a customized perfusion protocol, the decellularization process preserved the ultrastructural extracellular matrix components, functional characteristics of the native microvascular and the bile drainage network of the liver, and growth factors necessary for angiogenesis and liver regeneration. Furthermore, isolated hepatocytes engrafted and reorganized in the porcine decellularized livers using a human-sized organ culture system. These results provide proof-of-principle for the generation of a human-sized, three-dimensional organ scaffold as a potential structure for human liver grafts reconstruction for transplantation to treat liver disease.

Safety assessment of intraportal liver cell application in New Zealand white rabbits under GLP conditions

Liver cell transplantation (LCT) is considered a new therapeutic strategy for the treatment of acute liver failure and inborn metabolic defects of the liver. Although minimally invasive, known safety risks of the method include portal vein thrombosis and pulmonary embolism. Since no systematic data on these potential side effects exist, we investigated the toxicological profile of repeated intraportal infusion of allogeneic liver cells in 30 rabbits under GLP conditions. Rabbit liver cells were administered once daily for 6 consecutive days at 3 different dose levels, followed by a 2-week recovery period. No test item-related mortality was observed. During cell infusion, clinical findings such as signs of apathy and hyperventilation, moderate elevations of liver enzymes ALT and AST and a slight decrease in AP were observed, all fully reversible. Cell therapy-related macroscopic and histological findings, especially in liver and lungs, were observed in animals of all dose groups. In conclusion, the liver and lungs were identified as potential toxicological target organs of intraportal allogeneic liver cell infusion. A NOAEL (no observed adverse effect level) was not defined because of findings observed also in the low-dose group. No unexpected reactions became apparent in this GLP study. Overall, LCT at total doses up to 12 % (2 % daily over 6 days) of the total liver cell count were tolerated in rabbits. Observed adverse effects are not considered critical for treatment in the intended patient populations provided that a thorough monitoring of safety relevant parameters is in place during the application procedure.

MicroRNA-375 targets AEG-1 in hepatocellular carcinoma and suppresses liver cancer cell growth in vitro and in vivo

MicroRNAs (miRNAs) are believed to have fundamental roles in tumorigenesis and have great potential for the diagnosis and treatment of cancer. However, the roles of miRNAs in hepatocellular carcinogenesis are still not fully elucidated. We investigated the aberrantly expressed miRNAs involved in hepatoma by comparison of miRNA expression profiles in cancerous hepatocytes with normal primary human hepatocytes, and 37 dysregulated miRNAs were screened out by twofold change with a significant difference (P<0.05). Clustering analysis based on 13 miRNAs with changes over 15-folds showed that the miRNA expression patterns between the cancerous and normal hepatocytes were clearly different. Among the 13 miRNAs, we found that miR-375 was significantly downregulated in hepatocellular carcinoma (HCC) tissues and cell lines. Overexpression of miR-375 in liver cancer cells decreased cell proliferation, clonogenicity, migration/invasion and also induced G1 arrest and apoptosis. To unveil the molecular mechanism of miR-375-mediated phenotype in hepatoma cells described above, we examined the putative targets using bioinformatics tools and found that astrocyte elevated gene-1 (AEG-1) was a potential target of miR-375. Then we demonstrated that miR-375 bound directly to the 3'-untranslated region of AEG-1 and inhibited the expression of AEG-1. TaqMan quantitative reverse transcriptase-PCR and western blot analysis showed that miR-375 expression was inversely correlated with AEG-1 expression in HCC tissues. Knockdown of AEG-1 by RNAi in HCC cells, similar to miR-375 overexpression, suppressed tumor properties. Ectopic expression of AEG-1, conversely, could partially reverse the antitumor effects of miR-375. In a mouse model, therapeutic administration of cholesterol-conjugated 2'-O-methyl-modified miR-375 mimics (Chol-miR-375) could significantly suppress the growth of hepatoma xenografts in nude mice. In conclusion, our findings indicate that miR-375 targets AEG-1 in HCC and suppresses liver cancer cell growth in vitro and in vivo, and highlight the therapeutic potential of miR-375 in HCC treatment.

Establishment of an immortalized porcine liver cell line JSNK-1 with retroviral transduction of SV40T

Maintenance of freshly isolated porcine liver cells in vitro is limited for a short period of time. Therefore, establishment of easy handling cell lines is extremely important for in vitro study for liver cells and their possible utilization for cell differentiation and growth of stem cells. Porcine liver cells were transduced with a retroviral vector SSR#69 expressing SV40T, one of SSR#69-immortalized porcine liver cell lines, JSNK-1, was established and characterized. Morphology of JSNK-1 cells was spindle shaped. When the cells became confluent, JSNK-1 cells revealed hills-and-valleys pattern. In the presence of vitamin A, JSNK-1 cells showed big droplets inside the cytoplasm, which were positive with PAS staining. JSNK-1 cells showed the gene expression of collagen type 1α1, collagen type 1α2, FLT-1, β-actin, and SV40T. Immunostaining study revealed that JSNK-1 cells produced collagen, vimentin, and α-smooth muscle actin. JSNK-1 cells possessed the characteristics of the liver stellate cells. JSNK-1 cells produced hepatocyte growth factor (HGF) in a time-dependent manner. When cocultured with iPS cells towards the hepatic differentiation, JSNK-1 cells facilitated their hepatic differentiation in terms of albumin production. In conclusion, JSNK-1 cells would be valuable in the study of liver stellate cell pathophysiology and contribute to the optimization of hepatic differentiation of iPS cells.

Monitoring of Liver Cell Transplantation in a Preclinical Swine Model Using Magnetic Resonance Imaging

Liver cell transplantation (LCT) is a promising treatment approach for certain liver diseases, but clinical implementation requires methods for noninvasive follow-up. Labeling with superparamagnetic iron oxide particles can enable the detection of cells with magnetic resonance imaging (MRI). We investigated the feasibility of monitoring transplanted liver cells by MRI in a preclinical swine model and used this approach to evaluate different routes for cell application. Liver cells were isolated from landrace piglets and labeled with micron-sized iron oxide particles (MPIO) in adhesion. Labeled cells (n = 10), native cells (n = 3), or pure particles (n = 4) were transplanted to minipigs via intraportal infusion into the liver, direct injection into the splenic parenchyma, or intra-arterial infusion to the spleen. Recipients were investigated by repeated 3.0 Tesla MRI and computed tomography angiography up to 8 weeks after transplantation. Labeling with MPIO, which are known to have a strong effect on the magnetic field, enabled noninvasive detection of cell aggregates by MRI. Following intraportal application, which is commonly applied for clinical LCT, MRI was able to visualize the microembolization of transplanted cells in the liver that were not detected by conventional imaging modalities. Cells directly injected into the spleen were retained, whereas cell infusions intra-arterially into the spleen led to translocation and engraftment of transplanted cells in the liver, with significantly fewer microembolisms compared to intraportal application. These findings demonstrate that MRI can be a valuable tool for noninvasive elucidation of cellular processes of LCT and-if clinically applicable MPIO are available-for monitoring of LCT under clinical conditions. Moreover, the results clarify mechanisms relevant for clinical practice of LCT, suggesting that the intra-arterial route to the spleen deserves further evaluation.

An improved purification approach with high cell viability and low cell loss for cryopreserved hepatocytes

A modified purification procedure is described for effectively eliminating dead cells after hepatocyte cryopreservation. Isolated hepatocytes from six pig tissue samples were cryopreserved in liquid nitrogen for 2 weeks. After thawing, we developed a pre-incubation step prior to gradient centrifugation. The hepatocytes were subsequent cultured in suspension overnight (12-16 h), and then dead cells were eliminated by Ficoll 400 purification. The results showed that a high viability (mean of 96%) of cells was obtained, with a low viable cell loss in number (2-5%), by using this modified method.

Hepatocyte Paraffin 1 Immunoreactivity in Early Colon Carcinogenesis

Background

This study was aimed at evaluating the correlation between Hepatocyte paraffin 1 (Hep par 1) and colorectal cancer.

Methods

To this end, 50 intestinal biopsies were analyzed including 10 colorectal polyps with low grade dysplasia, 10 with high grade dysplasia, 10 colorectal adenocarcinomas, 10 specimens of normal ileum and 10 of normal colon mucosa. Tissue sections were immunostained for Hep par 1 utilizing a commercial antibody. Normal colonic mucosa did not express Hep par 1.

Results

Immunoreactivity for Hep par 1 was detected in 20% of polyps with low grade dysplasia, 50% of polyps with high grade dysplasia and 60% of colorectal carcinomas. Hep par 1 was frequently detected in the deepest areas of adenocarcinomas mainly in infiltrating tumour cells.

Conclusions

Our data show that Hep par 1 immunoreactivity in human colon carcinogenesis is correlated with progression from low grade to high grade dysplasia and adenocarcinoma. In clinical practice, our data show that caution should be taken in utilizing Hep par 1 as the sole tool in differentiating hepatocellular carcinoma from a liver metastasis of colon adenocarcinoma. Our data encourage further investigations into the potential role played by Hep par 1 in gastrointestinal carcinogenesis.

Development of a swine model of secondary liver tumor from a genetically induced swine fibroblast cell line

AIM

Metastatic disease is the most common liver tumor. Although alternative therapies have been developed for non-surgical candidates, those therapies lacked ideal testing prior to clinical application because of a paucity of large animal models. The purpose of the present study was to develop a model for secondary liver tumor in a large animal.

MATERIAL AND METHODS

Fibroblasts were isolated from swine ear lobules and then transfected with amphotrophic retroviruses encoding human or murine genetic material (hTERT, p53(DD), cyclinD-1, CDK4(R24C), Myc (T58A), Ras(G12V)). Transformed cell lines were finally inoculated subcutaneously (s.c.) into: 1) immunodeficient mice (nude), 2) immunocompetent mice (wild type), 3) immunosuppressed swine (under tacrolimus or corticosteroids), 4) immunocompetent swine, and 5) into the liver and portal circulation of swine under steroid-based immunosuppression.

RESULTS

In the murine model, tumor growth was evident in 100% of the nude mice (n=5), with a peak size of 20 mm (15.22+/-4.5 mm; mean+/-SD) at the time of sacrifice (3 weeks). Tumor growth was evident in 71% of the wild mice (n=21), with a peak size of 7.8 mm (4.19+/-1.1 mm) by the third week of growth. In the swine model, tumor growth was evident in 75% (3/4 ears; n=2) of swine under tacrolimus-based immunosuppression versus 50% of swine under steroids-based immunosuppression (n=2). Tumor growth was slow in two animals, while in one animal the tumor was larger with a peak growth of 42 mm at 3 weeks. The tumor pattern in the ear lobules was characterized by slow growth, with a peak size of 6-8 mm in the immunocompetent swine at 3 weeks. All tumors were shown to be malignant by histology. In contrast, inoculums of the transformed fibroblast cell line in swine livers showed no evidence of tumor growth at 3 weeks.

CONCLUSIONS

Development of a transformed swine fibroblast cell line was successful, resulting in an in vivo malignant tumor. Cell line inoculums had tumorigenic properties in nude mice, wild-type mice, and immunosuppressed swine, as judged by uncontrolled cell growth, invasion of surrounding tissue, neoangiogenesis, and invasion of normal vasculature, resulting in the formation of tumor nodules. Such properties were not observed in swine upon inoculation into the liver/portal circulation.

Survival of liver failure pigs by transplantation of reversibly immortalized human hepatocytes with Tamoxifen-mediated self-recombination

BACKGROUND/AIMS

Hepatocyte transplantation and bioartificial liver treatment are attractive alternatives to liver transplantation. The availability of well-characterized human hepatocyte lines facilitates such cell therapies.

METHODS

Human hepatocytes were immortalized with a retroviral vector SSR#197 expressing catalytic subunit of human telomerase reverse transcriptase (hTERT) and enhanced green fluorescent protein (EGFP) cDNAs flanked by a pair of loxP recombination targets. Then, Tamoxifen-dependent Cre recombinase was expressed in SSR#197-immortalized hepatocytes. Cre/LoxP recombination was performed in the established cells by simple exposure to 500 nM Tamoxifen for a week. Then, the reverted population of the cells was recovered by EGFP-negative cell sorting and characterized in vitro and in vivo using a pig model of acute liver failure (ALF) induced by d-galactosamine (0.5 g/kg) injection.

RESULTS

A human hepatocyte cell line 16T-3 was established. Reverted 16-T3 cells showed the increased expression of hepatic markers in association with enhanced levels of transcriptional factors. Compared to normal human hepatocytes, albumin production and lidocaine-metabolizing activities of reverted 16-T3 cells were 0.32 and 0.50-fold, respectively. Transplantation of reverted 16T-3 cells significantly prolonged the survival of ALF pigs.

CONCLUSIONS

Here we demonstrate the usefulness of Cre/LoxP -mediated reversible immortalization of human hepatocytes with Tamoxifen-mediated self-recombination.

Construction and transplantation of an engineered hepatic tissue using a polyaminourethane-coated nonwoven polytetrafluoroethylene fabric

BACKGROUND

Acute liver failure (ALF) is a serious condition that has a high mortality rate. Construction of an efficient culture and transplantation engineering system of hepatic tissue is an important approach to treat patients suffering from ALF to provide short-term hepatic support until the damaged liver spontaneously recovers or a donor liver becomes available for transplantation. Here, we evaluate the construction and transplantation of an engineered hepatic tissue (EHT) using primary isolated hepatocytes cultured onto polyaminourethane (PAU)-coated, nonwoven polytetrafluoroethylene (PTFE) fabric.

METHODS

The isolated hepatocytes cultured onto PAU-coated PTFE fabric were able to adhere and spread over the individual fibers of the net and formed hepatic clusters after 3 days, such clusters revealed Gap junctions and well-developed bile canaliculi.

RESULTS

When PAU-coated PTFE was utilized, ammonia-, and diazepam- metabolizing capacities and albumin production ability were significantly increased compared with collagen control. To test the function of this hepatic tissue in vivo, we transplanted a nonwoven PAU-coated PTFE fabric inoculated with one million hepatocytes on the surface of the spleen of Balb/c mice suffering from ALF induced by 90% hepatectomy, and found that this EHT prolonged the survival of liver failure-induced mice without adverse effects. Ultrastructure analyses showed good attachment of the cells on the surface of PTFE fabric and strong albumin expression seven days after the newly formed hepatic tissue was transplanted.

CONCLUSION

We have here demonstrated the efficient construction and transplantation of hepatic tissue using primary hepatocytes and PAU-coated PTFE fabric.

Evaluation of a bioartificial liver based on a nonwoven fabric bioreactor with porcine hepatocytes in pigs

BACKGROUND/AIMS

We developed a bioartificial liver (BAL) based on a direct hemoperfusion typed nonwoven fabric bioreactor containing porcine hepatocytes. In this study, the efficacy of our BAL was evaluated with a pig fulminant hepatic failure (FHF) model.

METHODS

FHF was induced with intravenous administration of D-galactosamine (1.3 g/kg) in each pig. Twelve hours post D-galactosamine injection, fifteen pigs were divided into: a BAL group (n = 5), in which pigs received the BAL treatment with 1.0 to 1.3 x 10(9) hepatocytes for 6 h, a sham BAL group (n = 5), in which pigs received the BAL treatment without hepatocytes, and a FHF group (n = 5), in which pigs only received intensive care. Parameters related to liver function and animal survival up to 168 h were determined.

RESULTS

In the BAL group, blood ammonia and plasma lactate levels were lower, and serum glucose levels and Fischer index were higher than those in the other two groups. Survival time of pigs in the BAL group was significantly prolonged as compared with the sham BAL and the FHF group.

CONCLUSIONS

The BAL based on a nonwoven fabric bioreactor containing porcine hepatocytes appears to be effective in the treatment of FHF in pigs.

Human hepatocyte transplantation for acute liver failure: state of the art and analysis of cell sources

Liver transplantation is the only treatment available for acute liver failure. However, mortality rates remain high because of the shortage of donor organs. Indeed up to 20% of patients with acute liver failure may survive without transplantation. In the last two decades, research has focused on the development of alternative or supportive measures to deal with acute liver failure; one of the most studied is hepatocyte transplantation, because it is thought that the function of the liver can only be replaced with a biological substrate characterized by functioning liver cells. Hepatocyte transplantation has been successful in many animal models of acute liver failure, although only several clinical attempts have been made in humans with encouraging but not yet convincing results, mainly because of the lack of a reliable source of live liver cells. Allogenic and xenogenic fresh or cryopreserved hepatocytes have been tested. Recent research has focused on fetal hepatocytes and progenitor liver cells of both hepatic and bone marrow origin. The ability to preserve and bank human hepatocytes would allow pooling of cells from multiple donors to increase the numbers for transplantation. The development of a reliable and large-scale available source of live liver cells would probably have a major impact on the introduction of hepatocyte transplantation in clinical practice.

A simple and highly effective method for the stable transduction of uncultured porcine hepatocytes using lentiviral vector

Gene therapy is an attractive approach for the treatment of a wide spectrum of liver diseases. Lentiviral vectors allow the stable integration of transgenes into the genome of nondividing differentiated cells including hepatocytes and could provide long-lasting expression of a therapeutic gene. To develop such approaches, preclinical studies in large animal models such as pigs are necessary to evaluate the feasibility and safety of stable lentiviral integration and long-term vector expression. In addition, effective lentivector-mediated gene transfer onto porcine hepatocytes could advance in cell-based therapies for acute liver failure. To investigate this issue, porcine hepatocytes were transduced in suspension immediately after their isolation in University of Wisconsin (UW) solution containing vitamin E. Up to 80% of hepatocytes stably expressed a GFP transgene after a single exposure to lentiviral vector coding for GFP under the control of either liver-specific or ubiquitous promoters. Moreover, porcine hepatocytes cryopreserved in UW solution containing fetal bovine serum, dimethyl sulfoxide, and vitamin E remained highly transducible with lentiviral vector after thawing. When thawed, transduced in suspension, and immediately transplanted into the spleen of immunodeficient mice, ex vivo lentivirally transgene marked xenogeneic hepatocytes were detected in murine liver. We demonstrated that porcine hepatocytes are highly susceptible to lentiviral vector and describe an easy methodology to efficiently, rapidly, and stably introduce transgenes into uncultured porcine hepatocytes.

Development of a porcine model of type 1 diabetes by total pancreatectomy and establishment of a glucose tolerance evaluation method

PURPOSE

To develop and evaluate the efficacy of diabetes-targeted cell therapies in humans, a reliable model in larger animals is highly desirable. This article reports the surgical technique of total pancreatectomy in pigs and the biochemical analysis of the characteristics of totally pancreatectomized pigs.

METHODS

Surgical total pancreatectomy was conducted in 23 pigs. Blood glucose, insulin, biochemistries, activity index, and intravenous glucose tolerance test (IVGTT) were examined to assess the pathophysiological profiles of diabetic pigs.

RESULTS

A total of 14 pigs successfully underwent total pancreatectomy without requiring biliary reconstruction and were analyzed in the present study. Activity index was decreased from day 5 on and the mean survival of totally pancreatectomized pigs was 7.6 +/- 2.7 days. No endogenous insulin secretion was confirmed in these pigs. Pigs which received total pancreatectomy demonstrated significantly higher levels of ketone bodies. IVGTT performed within 4 days after total pancreatectomy showed a spontaneous decrease in blood glucose levels despite an absence of endogenous insulin secretion. IVGTT on day 5 or later showed continued hyperglycemia in pigs with total pancreatectomy. Histological examination showed atrophy of hepatocytes and decreased glycogen storage in the liver and decreased mucus production of the small intestine.

CONCLUSION

This article describes a porcine model of diabetes created by total pancreatectomy and it analyzes the pathophysiological profiles in the animals. The present study has suggested that IVGTT on day 5 or later after total pancreatectomy is a reliable method to evaluate the efficacy of cell therapies.

Hepatocytes transplantation in rats with acute hepatic failure

AIM: To study the effect of allogeneic hepatocytes transplantation (HcT) intraperitoneally, intrasplenically or through vena portae in rats with acute hepatic failure (AHF) induced by D-galactosamine (D-gal).

METHODS: AHF rats were induced by D-gal. HcT was carried out 60h after intoxication, and all rats were divided into six groups: GroupⅠ received 2×10¹⁰/L hepatocytes 1 mL intraperitoneally with cyclosporin A (CsA) at 10 mg/kg simultaneously; Group Ⅱ received 1 mL normal saline (NS) intraperitoneally with CsA10 mg/kg; Group Ⅲ received 2×10¹⁰/L hepatocytes 1 mL through vena portae; Group Ⅳreceived 1mL NS through vena portae; Group Ⅴreceived 2×10¹⁰/L hepatocytes 1 mL intrasplenically; Group Ⅵ received 1 mL NS intrasplenically. After 1 wk the survival rates, liver function and liver histology of all rats were observed.

RESULTS: The survival rate of Group Ⅰ was higher than that of GroupⅡ (60 % vs 20%, P < 0.01), and their liver function and liver histology were obviously improved as compared with GroupⅡ. Similarly, the survival rate of Group Ⅴ was higher than that of Group Ⅵ (47% vs 20%, P < 0.05), and the liver function and liver histology were also improved in GroupⅤas compared with Group Ⅵ. On the other hand, the survival rate of Group Ⅲ was similar to that of GroupⅥ (20% vs 13.3%, P > 0.05), and their liver function and liver histology were also not improved significantly as compared with Group Ⅱ.

CONCLUSION: After HcT intraperitoneally or intrasplenically, the survival rates of AHF rats intoxicated with D-gal are increased, and the liver function and histology are also improved. On the contrary, the survival rate, liver function and liver histology of AHF rats through vena portae HcT are not improved.