Hepatocyte transplantation: A review of laboratory techniques and clinical experiences

A Simple and Useful Predictive Assay for Evaluating the Quality of Isolated Hepatocytes for Hepatocyte Transplantation

No optimal assay for assessing isolated hepatocytes before hepatocyte transplantation (HTx) has been established, therefore reliable and rapid assays are warranted. Isolated rat hepatocytes were dipped in a water bath (necrosis model), and were also cultured with Okadaic acid (apoptosis model) or vehicle, followed by cellular assessment including trypan blue exclusion (TBE) viability, ADP /ATP ratio, plating efficiency (PE), DNA quantity and ammonia elimination. Hepatocytes were transplanted into the liver of analbuminemic rats, subsequently engraftment was assessed by serum albumin and the histology of transplanted grafts. In the necrosis model, the ADP/ATP ratio was strongly and negatively correlated with the TBE (R² = 0.559, P < 0.001). In the apoptosis model, the ADP/ATP ratio assay, PE, DNA quantification and an ammonia elimination test clearly distinguished the groups (P < 0.001, respectively). The ADP/ATP ratio, PE and DNA quantity were well-correlated and the ammonia elimination was slightly correlated with the transplant outcome. TBE could not distinguish the groups and was not correlated with the outcome. The ADP/ATP ratio assay predicted the transplant outcome. PE and DNA quantification may improve the accuracy of the retrospective (evaluations require several days) quality assessment of hepatocytes. The ADP/ATP ratio assay, alone or with a short-term metabolic assay could improve the efficiency of HTx.

Agonist c-Met Monoclonal Antibody Augments the Proliferation of hiPSC-derived Hepatocyte-Like Cells and Improves Cell Transplantation Therapy for Liver Failure in Mice

Rationale: Hepatocyte-like cells (HLCs) derived from human induced pluripotent stem cells (hiPSCs) have been developed to address the shortage of primary human hepatocytes (PHHs) for therapeutic applications. However, the in vivo repopulation capacity of HLCs remains limited. This study investigated the roles of agonist antibody activating the c-Met receptor in promoting the in vivo proliferation and repopulation of engrafted PHHs and/or HLCs in mice with liver injuries due to different causes.

Methods: An agonist c-Met receptor antibody (5D5) was used to treat PHHs and hiPSC-HLCs in both cell culture and hepatocyte-engrafted immunodeficient mice mimicking various inherited and acquired liver diseases. The promoting roles and potential influence on the hepatic phenotype of the 5D5 regimen in cell transplantation-based therapeutic applications were systematically evaluated.

Results: In hiPSC-HLC cell cultures, 5D5 treatment significantly stimulated c-Met receptor downstream signalling pathways and accelerated cell proliferation in dose-dependent and reversible manners. In contrast, only slight but nonsignificant promotion was observed in 5D5-treated PHHs. In vivo administration of 5D5 greatly promoted the expansion of implanted hiPSC-HLCs in fumarylacetoacetate hydrolase (Fah) deficient mice, resulting in significantly increased human albumin levels and high human liver chimerism (over 40%) in the transplanted mice at week 8 after transplantation. More importantly, transplantation of hiPSC-HLCs in combination with 5D5 significantly prolonged animal survival and ameliorated liver pathological changes in mice with acute and/or chronic liver injuries caused by Fas agonistic antibody treatment, carbon tetrachloride treatment and/or tyrosinemic stress.

Conclusion: Our results demonstrated that the proliferation of hiPSC-HLCs can be enhanced by antibody-mediated modulation of c-Met signalling and facilitate hiPSC-HLC-based therapeutic applications for life-threatening liver diseases.

Clinical outcome of hepatocyte transplantation in four pediatric patients with inherited metabolic diseases

Hepatocyte transplantation (HT) has become an effective therapy for patients with metabolic inborn errors. We report the clinical outcome of four children with metabolic inborn errors that underwent HT, describing the cell infusion protocol and the metabolic outcome of transplanted patients. Cryopreserved hepatocytes were used as this allows scheduling of treatments. Functional competence (viability, cell attachment, major cytochrome P450 and UDP-glucuronosyltransferase 1A1 activities, and urea synthesis) and microbiological safety of cell batches were assessed prior to clinical use. Four pediatric patients with liver metabolic diseases [ornithine transcarbamylase (OTC) deficiency, Crigler-Najjar (CNI) syndrome, glycogen storage disease Ia (GSD-Ia), and tyrosinemia type I (TYR-I)] underwent HT. Indication for HT was based on severity of disease, deterioration of quality of life, and benefits for the patients, with the ultimate goal to improve their clinical status whenever liver transplantation (LT) was not indicated or to bridge LT. Cells were infused into the portal vein while monitoring portal flow. The protocol included antibiotic prophylaxis and immunosuppressant therapy. After HT, analytical data on the disease were obtained. The OTC-deficient patient showed a sustained decrease in plasma ammonia levels and increased urea production after HT. Further cell infusions could not be administered given a fatal nosocomial fungus sepsis 2 weeks after the last HT. The CNI and GSD-Ia patients improved their clinical status after HT. They displayed reduced serum bilirubin levels (by ca. 50%) and absence of hypoglycaemic episodes, respectively. In both cases, the HT contributed to stabilize their clinical status as LT was not indicated. In the infant with TYR-I, HT stabilized temporarily the biochemical parameters, resulting in the amelioration of his clinical status while diagnosis of the disease was unequivocally confirmed by full gene sequencing. In this patient, HT served as a bridge therapy to LT.

Blockade of endothelial G(i) protein enhances early engraftment in intraportal cell transplant to mouse liver

The limited availability of liver donors and recent progress in cell therapy technologies has centered interest on cell transplantation as a therapeutic alternative to orthotopic liver transplant for restoring liver function. Following transplant by intraportal perfusion, the main obstacle to cell integration in the parenchyma is the endothelial barrier. Transplanted cells form emboli in the portal branches, inducing ischemia and reperfusion injury, which cause disruption of endothelial impermeability and activate the immune system. Approximately 95% of transplanted cells fail to implant and die within hours by anoikis or are destroyed by the host immune system. Intravascular perfusion of Bordetella pertussis toxin (PTx) blocks endothelial G(i) proteins and acts as a reversible inducer of actin cytoskeleton reorganization, leading to interruption of cell confluence in vitro and increased vascular permeability in vivo. PTx treatment of the murine portal vascular tree 2 h before intraportal perfusion of embryonic stem cells facilitated rapid cell engraftment. By 2 h postperfusion, the number of implanted cells in treated mice was more than fivefold greater than in untreated controls, a difference that was maintained to at least 30 days posttransplant. We conclude that prior to cell transplant, PTx blockade of the G(i) protein pathway in liver endothelium promotes rapid, efficient cell implantation in liver parenchyma, and blocks chemokine receptor signaling, an essential step in early activation of the immune system.

Immediate intraportal transplantation of human bone marrow mesenchymal stem cells prevents death from fulminant hepatic failure in pigs

The effectiveness of human bone marrow mesenchymal stem cell (hBMSC) transplantation to treat acute and chronic liver injury has been demonstrated in animal models and in a few nonrandomized clinical trials. However, no studies have investigated hBMSC transplantation in the treatment of fulminant hepatic failure (FHF), especially in large animal (pig) models. The aim of this study was to demonstrate the safety, effectiveness, and underlying mechanism of hBMSC transplantation for treating FHF in pigs through the intraportal route. Human BMSCs (3 × 10(7) ) were transplanted into pigs with FHF via the intraportal route or peripheral vein immediately after D-galactosamine injection, and a sham group underwent intraportal transplantation (IPT) without cells (IPT, peripheral vein transplantation [PVT], and control groups, respectively, n = 15 per group). All of the animals in the PVT and control groups died of FHF within 96 hours. In contrast, 13 of 15 animals in the IPT group achieved long-term survival (>6 months). Immunohistochemistry demonstrated that transplanted hBMSC-derived hepatocytes in surviving animals were widely distributed in the hepatic lobules and the liver parenchyma from weeks 2 to 10. Thirty percent of the hepatocytes were hBMSC-derived. However, the number of transplanted cells decreased significantly at week 15. Only a few single cells were scattered in the regenerated liver lobules at week 20, and the liver tissues exhibited a nearly normal structure.

CONCLUSION

Immediate IPT of hBMSCs is a safe and effective treatment for FHF. The transplanted hBMSCs may quickly participate in liver regeneration via proliferation and transdifferentiation into hepatocytes during the initial stage of FHF. This method can possibly be used in future clinical therapy.

Factors from human embryonic stem cell-derived fibroblast-like cells promote topology-dependent hepatic differentiation in primate embryonic and induced pluripotent stem cells

The future clinical use of embryonic stem cell (ESC)-based hepatocyte replacement therapy depends on the development of an efficient procedure for differentiation of hepatocytes from ESCs. Here we report that a high density of human ESC-derived fibroblast-like cells (hESdFs) supported the efficient generation of hepatocyte-like cells with functional and mature hepatic phenotypes from primate ESCs and human induced pluripotent stem cells. Molecular and immunocytochemistry analyses revealed that hESdFs caused a rapid loss of pluripotency and induced a sequential endoderm-to-hepatocyte differentiation in the central area of ESC colonies. Knockdown experiments demonstrated that pluripotent stem cells were directed toward endodermal and hepatic lineages by FGF2 and activin A secreted from hESdFs. Furthermore, we found that the central region of ESC colonies was essential for the hepatic endoderm-specific differentiation, because its removal caused a complete disruption of endodermal differentiation. In conclusion, we describe a novel in vitro differentiation model and show that hESdF-secreted factors act in concert with regional features of ESC colonies to induce robust hepatic endoderm differentiation in primate pluripotent stem cells.

Functional assessment of the quality of human hepatocyte preparations for cell transplantation

Hepatocyte transplantation is an alternative therapy to orthotopic liver transplantation for the treatment of liver diseases. Good quality freshly isolated or cryopreserved human hepatocytes are needed for clinical transplantation. However, isolation, cryopreservation, and thawing processes can seriously impair hepatocyte viability and functionality. The aim of the present study was to develop a fast and sensitive procedure to estimate the quality of hepatocyte preparations prior to clinical cell infusion. To this end, cell viability, attachment efficiency, and metabolic competence (urea synthesis and drug-metabolizing P450 activities) were selected as objective criteria. Viability of hepatocyte suspension was estimated by trypan blue staining. DNA content of attached cells 50 min after hepatocyte platting to fibronectin/collagen-coated dishes was quantified to estimate adherence capacity. Urea production was determined after incubating hepatocyte suspensions with 2 mM C1NH4 for 30 min. The cytochrome P450 function was assayed by a 30-min incubation of hepatocyte suspension with a cocktail mixture containing selective substrates for seven individual P450 activities (CYP1A2, 2A6, 2C9, 2C19, 2D6, 2E1, and 3A4). The assay can be applied to both freshly isolated and cryopreserved hepatocyte suspensions, and the results are available within 1 h, which could help to make short-term decisions: 1) to assess the suitability for cell transplantation of a preparation of freshly isolated hepatocytes or a particular batch of thawed cells, or 2) to estimate the convenience of banking a particular cell preparation.

Intrasplenic or subperitoneal hepatocyte transplantation to increase survival after surgically induced hepatic failure?

BACKGROUND

As a basis for future clinical questions, we evaluated the efficacy of hepatocyte transplantation in a surgical model using a subperitoneal or intrasplenic approach for cell implantation.

METHODS

In rats, acute liver failure was induced by subtotal hepatectomy. Series of allogenic hepatocyte transplantations were performed by varying cell number, site, and sequence of cell transplantation.

RESULTS

Following subperitoneal or intrasplenic cell implantation subsequent to liver surgery, no survival benefit was achieved when compared to the control groups. However, intrasplenic cell implantation 24 h prior to liver surgery revealed a statistically significantly higher animal survival (72 vs. 29%).

CONCLUSION

According to our experience, both timing and site of cell implantation played an important role in hepatocyte transplantation. Intrasplenic hepatocyte transplantation 1 day before liver surgery showed the best results in terms of survival. Consequently, we were able to establish a model of hepatocyte transplantation which may be the basis for further investigations evaluating potential treatment modalities to overcome deleterious postoperative liver insufficiency.