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

Single-cell multi-omics deciphers hepatocyte dedifferentiation and illuminates maintenance strategies

Due to the similarity to human hepatocytes, porcine hepatocytes play an important role in hepatic research and drug evaluation. However, once hepatocytes were cultured in vitro, it was often prone to dedifferentiate, resulting in the loss of their characteristic features and normal functions, which impede their application in liver transplantation and hepatotoxic drugs evaluation. Up to now, this process has yet to be thoroughly investigated from the single-cell resolution and multi-omics perspective. In this study, we utilized 10× multiome technology to dissect the heterogeneity of porcine hepatocytes at different time points (Days 0, 1, 3, 5 and 7) during dedifferentiation. We comprehensively investigated cell heterogeneity, cellular dynamics, signalling pathways, potential gene targets, enhancer-driven gene regulatory networks, cell-cell communications of these cells and the conservation of mechanisms across species. We found that a series of critical signalling pathways driven by ERK, PI3K, Src and TGF-β were activated during this process, especially in the early stage of dedifferentiation. Based on these discoveries, we constructed a chemical combination targeting these pathways, which effectively inhibited the dedifferentiation of porcine hepatocytes in vitro. To validate the effectiveness of this combination, we transplanted such treated hepatocytes into FRGN mice, and the results demonstrated that these cells could effectively repopulate the liver and improve the survival of mice.

Therapeutic potential of menstrual blood stem cells in treating acute liver failure

BACKGROUND

Acute liver failure (ALF) is a significant and complex hepatic insult that may rapidly progress to life-threatening conditions. Recently, menstrual blood stem cells (MenSCs) have been identified as a group of easily accessible mesenchymal stem cells with the advantages of non-invasive acquisition, low immunogenicity, a greater capacity of self-renewal and multi-lineage differentiation, making them promising candidates for stem cell-based therapy to revolutionize the treatment strategies for liver failure.

AIM

To investigate the therapeutic potential of MenSCs for treating ALF in pigs and to dynamically trace the biodistribution of transplanted cells.

METHODS

MenSCs were labeled in vitro with PKH26, a lipophilic fluorescent dye. The treatment group received immediate transplantation of PKH26-labelled MenSCs (2.5 × 106/kg) via the portal vein after D-galactosamine injection, and the control group underwent sham operation. The survival time, liver function, and hepatic pathological changes were compared between the two groups. Three major organs (liver, lungs and spleen) were extracted from animals and imaged directly with the In vivo Imaging System (IVIS) at the predetermined time points. The regions of interest were drawn to quantify the cell uptake in different organs.

RESULTS

The labelling procedure did not affect the morphology, viability or multipotential differentiation of MenSCs. Biochemical analysis showed that the levels of alanine aminotransferase (ALT), aspartate aminotransferase (AST), total bilirubin (TBIL) and prothrombin time (PT) measured at selected time points 24 h after transplantation were significantly decreased in the treatment group (P < 0.05). The survival time of ALF animals was prolonged in the treatment group compared with the control group (75.75 ± 5.11 h vs 53.75 ± 2.37 h, log rank, P < 0.001). The liver pathological tissue in the MenSC treatment group showed obviously increased numbers of remaining hepatocytes and a comparatively slight necrotic degree and area. In addition, the IVIS imaging revealed that PKH26-positive MenSCs were clearly retained in the liver initially and then diffused through the systemic circulation. Interestingly, the signal intensity in the liver increased obviously at 36 h, which corresponded to the biochemical result that liver function deteriorated most rapidly at 24 - 36 h.

CONCLUSION

Our study demonstrates the therapeutic efficacy and homing ability of transplanted MenSCs in a large animal model of ALF and suggests that MenSC transplantation could be a promising strategy for treating ALF.

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.

Novel D-galactosamine-induced cynomolgus monkey model of acute liver failure

AIM

To establish a simplified, reproducible D-galactosamine-induced cynomolgus monkey model of acute liver failure having an appropriate treatment window.

METHODS

Sixteen cynomolgus monkeys were randomly divided into four groups (A, B, C and D) after intracranial pressure (ICP) sensor implantation. D-galactosamine at 0.3, 0.25, 0.20 + 0.05 (24 h interval), and 0.20 g/kg body weight, respectively, was injected via the small saphenous vein. Vital signs, ICP, biochemical indices, and inflammatory factors were recorded at 0, 12, 24, 36, 48, 72, 96, and 120 h after D-galactosamine administration. Progression of clinical manifestations, survival times, and results of H&E staining, TUNEL, and Masson staining were recorded.

RESULTS

Cynomolgus monkeys developed different degrees of debilitation, loss of appetite, and jaundice after D-galactosamine administration. Survival times of groups A, B, and C were 56 ± 8.7 h, 95 ± 5.5 h, and 99 ± 2.2 h, respectively, and in group D all monkeys survived the 144-h observation period except for one, which died at 136 h. Blood levels of ALT, AST, CK, LDH, TBiL, Cr, BUN, and ammonia, prothrombin time, ICP, endotoxin, and inflammatory markers [(tumor necrosis factor (TNF)-α, interleukin (IL)-1β, and IL-6)] significantly increased compared with baseline values in different groups (P < 0.05). Pathological results showed obvious liver cell necrosis that was positively correlated with the dose of D-galactosamine.

CONCLUSION

We successfully established a simplified, reproducible D-galactosamine-induced cynomolgus monkey model of acute liver failure, and the single or divided dosage of 0.25 g/kg is optimal for creating this model.

Efficacy of Fluidized Bed Bioartificial Liver in Treating Fulminant Hepatic Failure in Pigs: A Metabolomics Study

Bioartificial livers may act as a promising therapy for fulminant hepatic failure (FHF) with better accessibility and less injury compared to orthotopic liver transplantation. This study aims to evaluate the efficacy and safety of a fluidized bed bioartificial liver (FBBAL) and to explore its therapeutic mechanisms based on metabolomics. FHF was induced by D-galactosamine. Eighteen hours later, pigs were treated with an FBBAL containing encapsulated primary porcine hepatocytes (B group), with a sham FBBAL (containing cell-free capsules, S group) or with only intensive care (C group) for 6 h. Serum samples were assayed using ultra-performance liquid chromatography-mass spectrometry. The difference in survival time (51.6 ± 7.9 h vs. 49.3 ± 6.6 h) and serum metabolome was negligible between the S and C groups, whereas FBBAL treatment significantly prolonged survival time (70.4 ± 11.5h, P < 0.01) and perturbed the serum metabolome, resulting in a marked decrease in phosphatidylcholines, lysophosphatidylcholines, sphingomyelinase, and fatty acids and an increase in conjugated bile acids. The FBBAL exhibits some liver functions and may exert its therapeutic effect by altering the serum metabolome of FHF pigs. Moreover, alginate-chitosan capsules have less influence on serum metabolites. Nevertheless, the alterations were not universally beneficial, revealing that much should be done to improve the FBBAL.

Efficacy of coupled low-volume plasma exchange with plasma filtration adsorption in treating pigs with acute liver failure: A randomised study

BACKGROUND & AIMS

Extracorporeal blood purification systems for supportive therapy of liver failure are widely used. We developed a novel blood purification system, named Li's artificial liver system (Li-ALS), which couples low-volume plasma exchange (low-volume PE) with plasma filtration adsorption (PFA). This study aims to evaluate the efficacy of our novel system in pigs with acute liver failure (ALF).

METHODS

Thirty-two pigs were infused with D-galactosamine (1.3g/kg) to induce ALF. All animals were equally and randomly divided into four groups: the ALF control group received intensive care, the PFA group underwent five hour plasma recycling filtration and adsorption purification, the low-volume PE group received one hour low-volume PE, and the Li-ALS group underwent one hour low-volume PE, followed by five hour PFA. Intervention was initiated 36hours after drug administration. The efficacy of each treatment was assessed by survival time and improvement in hematological, biochemical, and immunohistological parameters.

RESULTS

Pigs in the Li-ALS group survived longer than those in the other groups (p<0.001, ALF control: 60±2h; PFA group: 74±2h; low-volume PE group: 75±2h; and Li-ALS group: 90±3h). Liver enzyme, bilirubin, bile acid and blood ammonia levels were decreased significantly after Li-ALS treatment, and increases in inflammatory cytokines were ameliorated. A higher hepatocyte regeneration index was also observed in the Li-ALS group.

CONCLUSION

Our novel Li-ALS could expedite liver regeneration and improve survival time; hence, it could be promising for treating ALF.

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.

Integration of single-layer skin hollow fibers and scaffolds develops a three-dimensional hybrid bioreactor for bioartificial livers

Bioartificial liver support systems are expected to be an effective therapy as a "bridge" for liver transplantation or reversible acute liver disease. A major roadblock in the application of bioartificial livers is the need for a bioreactor that fully meets the requirements of hepatocyte culture, mass transfer and immunobarriers. In this study, we developed a three-dimensional hybrid bioreactor (3DHB) on a base of single-layer skin polyethersulfone hollow fibers by integrating with polyurethane scaffolds. The mass transfer of bilirubin and albumin from the intracapillary space to the extracapillary space of the hollow fibers was not significantly different between 3DHBs and hollow fiber bioreactors (HFBs). Cell viability staining showed that high-density hepatocytes were uniformly found in different regions of the 3DHB after 7 days of culture. Liver-specific functions of human mature hepatocytes cultured in the 3DHB, such as albumin secretion, urea production, ammonia removal rate and cytochrome P450 activity, were maintained stably and were significantly higher compared with the HFB. These results indicated that the 3DHB has good mass transfer and improves cell distribution and liver-specific functions. Meanwhile, the ammonia and unconjugated bilirubin concentrations in plasma from patients with liver failure were significantly decreased during 6 h of circulation by hepatocytes cultured in the 3DHB. Most hepatocytes in the 3DHB were viable after 6 h exposure to the patient plasma. We further demonstrated that bioartificial liver systems with 3DHB can remove toxins from and endure the deleterious effects of the patient plasma. Therefore, the 3DHB has the potential to accomplish different actions for the clinical application of bioartificial livers.

Composite nonwovens in medical applications

This chapter reviews the role of composite nonwovens in medical applications. It covers surgical gowns, clinical wearable products, wipes, wound dressings, pads, swabs, scaffolds for tissue engineering, hernia meshes, filtration materials, and incontinence products. Commercially available, innovatively designed composite nonwovens for various medical applications are improving the quality of life of many people. Specific research needs have been highlighted to further improve the effectiveness of these products. The chapter ends with some perspectives for the use of composite nonwovens in medical applications in the future.

A promising hepatocyte-like cell line, CCL-13, exhibits good liver function both in vitro and in an acute liver failure model

BACKGROUND

A great many patients awaiting liver transplantation die because of the shortage of donor livers. To resolve the problem, liver support systems like bioartificial livers (BALs) have become subjects of active investigation. However, the problem with BALs is that it is difficult to find a source of healthy hepatic cells with good liver function. This study explored the possibility of employing Chang liver cells (ATCC CCL-13), a human hepatoma cell line as a source for liver support.

METHODS

To evaluate the function of Chang liver cells in vitro, hepatocyte markers were measured by Western blotting and laser confocal microscopy. The gene expression of hepatic markers was examined by reverse transcriptase polymerase chain reaction (RT-PCR). After acute liver failure (ALF) was established by 90% partial hepatectomy, Chang liver cells were intrasplenically transplanted for treatment.

RESULTS

In vitro, Western blotting and laser confocal microscopy showed conspicuous expression of liver function markers, such as albumin, uridine diphosphate glucuronosyltransferase, and cytochrome P450 3A4 by Chang liver cells. RT-PCR revealed expression of related genes at the mRNA level. The survival of rats receiving transplanted Chang liver cells reached 40% versus 0% among the controls (P < .01). Liver function of rats receiving transplanted Chang liver cells was improved at 24 hours after ALF, as evidenced by decreased levels of alanine transaminase, aspartate aminotransferase, bilirubin, and alkaline phosphate.

CONCLUSIONS

Chang liver cells, which express liver function markers and exert obvious liver-protective effects in ALF can serve in liver support systems.

Immunosafety evaluation of a multilayer flat-plate bioartificial liver

INTRODUCTION

To study and evaluate the immunosafety of our newly developed multilayer flat-plate bioartificial liver (BAL) in treatment of canines with acute liver failure.

METHODS

Fresh porcine hepatocytes and bone marrow mesenchymal stem cells were cocultured in new BAL. Ten canine models with acute liver failure were set up through D-galactosamine administration; 24 hours after administration, the beagles were randomly allocated to a 6-hour treatment with the BAL. The beagles were divided into 2 groups by treatment times. Group 1 beagles (n = 5) received a single BAL treatment. Group 2 beagles (n = 5) received 3 BAL treatments. The hemodynamic, hematologic response and humoral immune responses to BAL therapy were studied before and after treatments.

RESULTS

All beagles remained hemodynamically and hematologically stable during BAL treatments. The levels of IgG and IgM were similar before and after treatment after a single treatment. In addition, the level of CH50 in group 1 slightly decreased after the initiation of BAL treatment, and then the level recovered to baseline quickly after treatments. Time-course changes of the levels of antibodies and CH50 after 3 treatments in group 2 were similar to group 1. Only trace levels of IgG were detected in BAL medium after treatments.

CONCLUSION

The multilayer flat-plate BAL showed a great immunosafety in the treatment of canines with acute liver failure and exhibited a good prospect of its use in clinic.

Therapeutic potential of transplanted placental mesenchymal stem cells in treating Chinese miniature pigs with acute liver failure

BACKGROUND

Stem cell-based therapy to treat liver diseases is a focus of current research worldwide. So far, most such studies depend on rodent hepatic failure models. The purpose of this study was to isolate mesenchymal stem cells from human placenta (hPMSCs) and determine their therapeutic potential for treating Chinese experimental miniature pigs with acute liver failure (ALF).

METHODS

hPMSCs were isolated and analyzed for their purity and differentiation potential before being employed as the donor cells for transplantation. ALF models of Chinese experimental miniature pigs were established and divided into four groups: no cell transplantation; hPMSCs transplantation via the jugular vein; X-ray-treated hPMSCs transplantation via the portal vein; and hPMSCs transplantation via the portal vein. The restoration of biological functions of the livers receiving transplantation was assessed via a variety of approaches such as mortality rate determination, serum biochemical analysis, and histological, immunohistochemical, and genetic analysis.

RESULTS

hPMSCs expressed high levels of CD29, CD73, CD13, and CD90, had adipogenic, osteogenic, and hepatic differentiation potential. They improved liver functions in vivo after transplantation into the D-galactosamine-injured pig livers as evidenced by the fact that ALT, AST, ALP, CHE, TBIL, and TBA concentrations returned to normal levels in recipient ALF pigs. Meanwhile, histological data revealed that transplantation of hPMSCs via the portal vein reduced liver inflammation, decreased hepatic denaturation and necrosis, and promoted liver regeneration. These ameliorations were not found in the other three groups. The result of 7-day survival rates suggested that hPMSCs transplantation via the portal vein was able to significantly prolong the survival of ALF pigs compared with the other three groups. Histochemistry and RT-PCR results confirmed the presence of transplanted human cells in recipient pig livers (Groups III, IV).

CONCLUSIONS

Our data revealed that hPMSCs could not only differentiate into hepatocyte-like cells in vitro and in vivo, but could also prolong the survival time of ALF pigs. Regarding the transplantation pathways, the left branch of the portal vein inside the liver was superior to the jugular vein pathway. Thus, hPMSCs transplantation through the portal vein by B-ultrasonography may represent a superior approach for treating liver diseases.

Bioartificial liver system based on choanoid fluidized bed bioreactor improve the survival time of fulminant hepatic failure pigs

Bioartificial liver (BAL) support system has been proposed as potential treatment method for end-stage liver diseases. We described an improved BAL system based on a choanoid fluidized bed bioreactor containing alginate-chitosan encapsulated primary porcine hepatocytes. The feasibility, safety, and efficiency of this device were estimated using an allogeneic fulminant hepatic failure (FHF) model. FHF was induced with intravenous administration of D-galactosamine. Thirty FHF pigs were divided into three groups: (1) an FHF group which was only given intensive care; (2) a sham BAL group which was treated with the BAL system with empty encapsulation, and (3) a BAL group which was treated with the BAL system containing encapsulated freshly isolated primary porcine hepatocytes. The survival times and biochemical parameters of these animals were measured, and properties of the encapsulations and hepatocytes before and after perfusion were also evaluated. Compared to the two control groups, the BAL-treated group had prolonged the survival time and decreased the blood lactate levels, blood glucose, and amino acids remained stable. No obvious ruptured beads or statistical decline in viability or function of encapsulated hepatocytes were observed. This new fluidized bed BAL system is safe and efficient. It may represent a feasible alternative in the treatment of liver failure.

An overview of animal models for investigating the pathogenesis and therapeutic strategies in acute hepatic failure

Acute hepatic failure (AHF) is a severe liver injury accompanied by hepatic encephalopathy which causes multiorgan failure with an extremely high mortality rate, even if intensive care is provided. Management of severe AHF continues to be one of the most challenging problems in clinical medicine. Liver transplantation has been shown to be the most effective therapy, but the procedure is limited by shortage of donor organs. Although a number of clinical trials testing different liver assist devices are under way, these systems alone have no significant effect on patient survival and are only regarded as a useful approach to bridge patients with AHF to liver transplantation. As a result, reproducible experimental animal models resembling the clinical conditions are still needed. The three main approaches used to create an animal model for AHF are: surgical procedures, toxic liver injury and infective procedures. Most common models are based on surgical techniques (total/partial hepatectomy, complete/transient devascularization) or the use of hepatotoxic drugs (acetaminophen, galactosamine, thioacetamide, and others), and very few satisfactory viral models are available. We have recently developed a viral model of AHF by means of the inoculation of rabbits with the virus of rabbit hemorrhagic disease. This model displays biochemical and histological characteristics, and clinical features that resemble those in human AHF. In the present article an overview is given of the most widely used animal models of AHF, and their main advantages and disadvantages are reviewed.

Management of Hepatitis C virus Genotype 2 or 3 Infection: Treatment Optimization on the Basis of Virological Response

Current guidelines recommend a full 24-week regimen for all patients undergoing treatment for genotype 2 or 3 hepatitis C virus (HCV) infection. Recent data from two large randomized studies, one with pegylated interferon-α2a plus ribavirin (RBV) and one with pegylated interferon-α2b plus RBV assessed treatment duration and on-treatment predictors, such as rapid virological response (RVR; HCV RNA <50 IU/ml at week 4) or sustained virological response rates. Overall, these studies have shown that abbreviated regimens are generally less effective than standard 24-week regimens in genotype 2 or 3 patients because of a higher rate of relapse. However, abbreviated treatment might be offered to selected patients with an RVR provided that they have a low baseline viral load and minimal hepatic fibrosis.

Comparison between bioartificial and artificial liver for the treatment of acute liver failure in pigs

AIM: To characterize and evaluate the therapeutic efficacy of bioartificial liver (BAL) as compared to that of continuous hemodiafiltration (CHDF) with plasma exchange (PE), which is the current standard therapy for fulminant hepatic failure (FHF) in Japan.

METHODS: Pigs with hepatic devascularization were divided into three groups: (1) a non-treatment group (NT; n = 4); (2) a BAL treatment group (BAL; n = 4), (3) a PE + CHDF treatment group using 1.5 L of normal porcine plasma with CHDF (PE + CHDF, n = 4). Our BAL system consisted of a hollow fiber module with 0.2 μm pores and 1 x 10¹⁰ of microcarrier-attached hepatocytes inoculated into the extra-fiber space. Each treatment was initiated 4 h after hepatic devascularization.

RESULTS: The pigs in the BAL and the PE + CHDF groups survived longer than those in the NT group. The elimination capacity of blood ammonia by both BAL and PE + CHDF was significantly higher than that in NT. Aromatic amino acids (AAA) were selectively eliminated by BAL, whereas both AAA and branched chain amino acids, which are beneficial for life, were eliminated by PE + CHDF. Electrolytes maintenance and acid-base balance were better in the CPE + CHDF group than that in the BAL group.

CONCLUSION: Our results suggest that PE + CHDF eliminate all factors regardless of benefits, whereas BAL selectively metabolizes toxic factors such as AAA. However since PE + CHDF maintain electrolytes and acid-base balance, a combination therapy of BAL plus CPE + CHDF might be more effective for FHF.