Hepatocyte transplantation followed by auxiliary liver transplantation--a novel treatment for ornithine transcarbamylase deficiency

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.

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.

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.

Repeated transplantation of hepatocytes prevents fulminant hepatitis in a rat model of Wilson's disease

The outcome of consecutive hepatocyte transplants was explored in a rat model of Wilson's disease before the onset of fulminant hepatitis without preconditioning regimens. Rats received a high-copper diet in order to induce a rapid induction of liver failure. Sham-operated rats (15/15) developed jaundice and fulminant hepatitis, and they died within 4 weeks of first transplantation. Despite the continuation of a high dietary copper challenge, long-term survival was observed for a notable proportion of the transplanted animals (7/18). All survivors displayed normalized levels of hepatitis-associated serum markers and ceruloplasmin oxidase activity by posttransplant days 50 and 98, respectively. The liver copper concentrations, the liver histology, and the expression of marker genes were significantly restored within 4 months of transplantation in comparison with the control group. The high expression of a copper transporter gene (ATPase Cu++ transporting beta polypeptide) in the livers of the survivors indicated a high rate of repopulation by donor hepatocytes. Our data suggest that repeated cell transplantation can overcome the limitations of a single therapy session in rats with severe hepatic disease by functionally restoring the host liver without preconditioning.

Monitoring transplanted adipose tissue-derived stem cells combined with heparin in the liver by fluorescence imaging using quantum dots

Adipose tissue-derived stem cell (ASC) transplantation, when used in combination with heparin, has proven to be an effective treatment for acute liver failure in mice. However, the behavior and organ-specific accumulation of transplanted ASCs alone or in combination with heparin is poorly understood. In this paper, we investigated whether quantum dots (QDs) labeling using octa-arginine peptide (R8) for ASCs could be applied for in vivo fluorescence imaging in mice with acute liver failure, and analyzed the behavior and organ-specific accumulation of ASCs that were transplanted alone or in combination with heparin using an IVIS(®) Spectrum analysis. Almost all of the transplanted ASCs were observed to accumulate in the lungs within 10 min without heparin. However, when heparin was used in combination with the ASCs, the accumulation of the transplanted ASCs was found not only in the lungs but also in the liver. The region of interest (ROI) analysis of ex vivo fluorescence imaging showed that the accumulation rate of transplanted ASCs in the liver increased to about 30%. In the time course analysis, the accumulation rate of ASCs in the liver was about 10% in 1 day and was maintained at that level for at least 2 day. We observed that heparin was effective for increasing the accumulation of transplanted ASCs in the liver using fluorescence imaging technology. We suggest that fluorescence imaging by means of QDs labeling using R8 can be useful for tracing the transplanted cells.

High urgency liver transplantation in ornithine transcarbamylase deficiency presenting with acute liver failure

OTCD can present with ALF at any age. Under adequate therapy symptoms resolve quickly. We report a three-yr-old girl with the manifestation of an OTCD as ALF. Despite adequate pharmacotherapy and protein restriction, the patient deteriorated and developed hepatic encephalopathy. A high urgency liver transplantation was performed and the patient recovered completely. We conclude that in patients with ALF urea cycle defects in general and OTCD in particular should be considered as differential diagnosis. Patients should be managed in a center that has the capacity for an emergency liver transplantation.

The instant blood-mediated inflammatory reaction characterized in hepatocyte transplantation

BACKGROUND

Hepatocyte transplantation (HcTx) has proven to be a safe procedure, although the functional results have been unsatisfactory, probably due to insufficient engraftment or a loss of transplanted mass or function. In this study, we investigate whether hepatocytes in contact with blood induce an inflammatory reaction leading to, similar to what happens in clinical islet transplantation, an instant blood-mediated inflammatory reaction (IBMIR) resulting in an early loss of transplanted cells.

METHODS

By using an experimental model that mimics the portal vein blood flow, we could study different parameters reflecting the effects on the innate immunity elicited by hepatocytes in contact with ABO-matched human blood.

RESULTS

We report that all aspects of the IBMIR such as platelet and granulocyte consumption, coagulation, and complement activation were demonstrated. Addition of various specific inhibitors of coagulation allowed us to clearly delineate the various stages of the hepatocyte-triggered IBMIR and show that the reaction was triggered by tissue factor. Analysis of a case of clinical HcTx showed that hepatocyte-induced IBMIR also occurs in vivo. Both the inflammatory and the coagulation aspects were controlled by low-molecular-weight dextran sulfate.

CONCLUSION

Isolated hepatocytes in contact with blood induce the IBMIR in vitro, and there are indications that these events are also relevant in vivo. According to these findings, HcTx would benefit from controlling a wider range of signals from the innate immune system.

Cell therapeutic options in liver diseases: cell types, medical devices and regulatory issues

Although significant progress has been made in the field of orthotopic liver transplantation, cell-based therapies seem to be a promising alternative to whole-organ transplantation. The reasons are manifold but organ shortage is the main cause for this approach. However, many problems such as the question which cell type should be used or which application site is best for transplantation have been raised. In addition, some clinicians have had success by cultivating liver cells in bioreactors for temporary life support. Besides answering the question which cell type, which injection site or even which culture form should be used for liver support recent international harmonization of legal requirements is needed to be addressed by clinicians, scientists and companies dealing with cellular therapies. We here briefly summarize the possible cell types used to partially or temporarily correct liver diseases, the most recent development of bioreactor technology and important regulatory issues.

Paediatric liver transplantation for metabolic disorders. Part 1: Liver-based metabolic disorders without liver lesions

Liver-based metabolic disorders account for 10 to 15% of the indications for paediatric liver transplantation. In the last three decades, important progress has been made in the understanding of these diseases, and new therapies have emerged. Concomitantly, medical and surgical innovations have lead to improved results of paediatric liver transplantation, patient survival nowadays exceeding 80% 10-year after surgery with close to normal quality of life in most survivors. This review is a practical update on medical therapy, indications and results of liver transplantation, and potential future therapies, for the main liver-based metabolic disorders in which paediatric liver transplantation may be considered. Part 1 focuses on metabolic based liver disorders without liver lesions, and part 2 on metabolic liver diseases with liver lesions.

Therapeutic liver repopulation for phenylketonuria

Problems with long-term dietary compliance in phenylketonuria (PKU) necessitate the development of alternative treatment approaches. Therapeutic liver repopulation with phenylalanine hydroxylase (PAH)-expressing cells following hepatocyte or haematopoietic stem cell transplantation has been investigated as a possible novel treatment approach for PKU. Successful therapeutic liver repopulation requires both a stimulus for liver regeneration at the time of cell transplantation and a selective growth advantage for the PAH+ donor cells. Unfortunately, wild-type PAH+ hepatocytes do not enjoy any growth advantage over PAH- cells. Successful correction of hyperphenylalaninemia following therapeutic liver repopulation has been accomplished only in an animal model that yields a selective advantage for the donor cells. Haematopoietic stem cell (HSC)-mediated therapeutic liver repopulation has not been reported in any hyperphenylalaninemic system, and the success of HSC-mediated liver repopulation for PKU may be limited by the slow kinetics of this approach. If therapeutic liver repopulation is to be employed successfully in humans with PKU, an effective method of providing a selective growth advantage for the donor cells must be developed. If this can be achieved, liver repopulation with 10-20% wild-type hepatocytes will likely completely normalize Phe clearance in individuals with PKU.

Cell delivery: from cell transplantation to organ engineering

Cell populations derived from adult tissue and stem cells possess a great expectation for the treatment of several diseases. Great efforts have been made to generate cells with therapeutic impact from stem cells. However, it is clear that the development of systems to deliver such cells to induce efficient engraftment, growth, and function is a real necessity. Biologic and artificial scaffolds have received significant attention for their potential therapeutic application when use to form tissues in vitro and facilitate engraftment in vivo. Ultimately more sophisticated methods for decellularization of organs have been successfully used in tissue engineering and regenerative medicine applications. These decellularized tissues and organs appear to provide bioactive molecules and bioinductive properties to induce homing, differentiation, and proliferation of cells. The combination of decellularized organs and stem cells may dramatically improve the survival, engraftment, and fate control of transplanted stem cells and their ultimate clinical utility, opening the doors to a new era of organ engineering.

Human hepatocyte transplantation: current experience and future challenges

Hepatocyte transplantation has shown potential as an additional treatment modality for certain diseases of the liver. To date, patients with liver-based metabolic disorders or acute liver failure have undergone hepatocyte transplantation in several centers around the world. Results from individual patients are promising, especially for the treatment of liver-based metabolic disorders, but the lack of controlled trials makes the interpretation of the findings difficult. The current source of isolated hepatocytes is donor organs that are unused or deemed unsuitable for liver transplantation. Hence the major challenge that this field is facing is the limited supply of donor organs that can provide good quality cells. Alternative sources of cells, including stem cells, are under investigation. This Review discusses the current bench-to-bedside issues and future challenges that need to be faced to allow the wider application of hepatocyte transplantation.

Monitoring of intraportal liver cell application in children

Despite recent advances and promising results in children, liver cell transplantation (LCT) should still be regarded as an experimental therapy. Several substantial complications are known from animal studies and individual patients. However, safety data on liver cell infusion in children are scarce. We used LCT in four children of different ages (3 weeks to 11 years, 3-40 kg) and underlying diseases [acute liver failure (n = 1), urea cycle disorders (n = 2), and Crigler-Najjar syndrome (n = 1)]. Vital parameters, portal vein flow (PVF), portal vein pressure (PVP), and liver enzymes were measured every 5 min during cell application and hourly thereafter between applications. An application protocol with discontinuation rules depending on changes in PVF and PVP was developed and successfully applied. Application was feasible in all children despite the catastrophic overall condition of the patient with acute liver failure. No application-related changes in vital parameters were found, and none of the children experienced clinical signs of portal vein thrombosis, pulmonary embolism, or anaphylactic reactions. Time courses for changes in PVF, PVP, and liver enzymes were obtained. Thorough monitoring of portal vein pressure and duplex sonography according to a defined protocol is likely to increase safety of cell application in pediatric LCT.

Liver, liver cell and stem cell transplantation for the treatment of urea cycle defects

Despite advances in pharmacological therapy of urea cycle disorders (UCDs), the overall long-term prognosis is poor, especially for neonatal manifestations. Transplantation of liver tissue or isolated cells appears suitable for transfer of the missing enzyme. Liver transplantation (LT) for UCDs has an excellent 5-year survival rate of approximately 90% and is the only way to completely cure the disease. However, major neurological damage can only be prevented if the operation is performed during the first months of life. Unfortunately, such early LTs have a substantial risk for peri- and postoperative complications, mostly caused by a relatively large liver graft. Liver cell transplantation (LCT) is less invasive than LT, but has still to be regarded as an experimental therapy with about 100 patients treated since its first use in 1993. UCDs are a model disease for LCT, because of the poor prognosis, mainly hepatic enzyme defects, and excellent outcome after LT. So far, 10 children underwent LCT for UCDs with very few technical complications and encouraging clinical results. A first prospective study on its use in severe neonatal UCDs has recently started. However, availability of hepatocytes is limited by the scarcity of donor livers; therefore the use of stem cells is under investigation. Several different cell types may be regarded as liver stem cells, and in vivo transformation into hepatocyte-like cells has been shown in animal studies. However, a clear proof of principle in animal models of human metabolic disease is still missing, which is the prerequisite for clinical application in humans.

Cryopreservation of human hepatocytes for clinical use

Cryopreservation of hepatocytes is important for use both in research and for clinical application in hepatocyte transplantation. Cryopreservation causes damage to hepatocytes with the result that cell viability and function is reduced on thawing compared to fresh cells. There are many different protocols reported for freezing human hepatocytes mainly using DMSO as cryoprotectant. In this chapter the current detailed protocols used for cryopreservation and thawing of human hepatocytes for cell transplantation at the Cell Isolation Unit at King's College Hospital, London, are described. All procedures must be performed in a clean GMP environment using materials and reagents which are of pharmaceutical grade. The cryopreservation media is UW solution with added 300 mM glucose containing 10% DMSO and the thawing solution is EMEM containing 2% HSA. Freezing is performed in a controlled-rate freezer using a stepwise cooling programme.

First example of hepatocyte transplantation to alleviate ornithine transcarbamylase deficiency, monitored by NMR-based metabonomics

We demonstrate the effective use of NMR spectroscopic profiles of urine and plasma from the first successful use of hepatocyte transplantation as a bridge to auxiliary partial orthotopic liver transplantation in a child antenatally diagnosed with severe ornithine transcarbamylase deficiency. In this single-patient study, NMR profiles indicated that the disrupted urea cycle could be normalized by hepatocyte cell infusion and this was confirmed using orthogonal partial least-squares-based chemometrics. However, despite dietary manipulations and adminstration of ammonia scavengers, the desired reduction in plasma ammonia was not consistently achieved between sessions of hepatocyte transplantation due to episodes of sepsis. A subsequent liver transplant corrected the metabolic abnormalities. The use of metabolic profiling has been shown to be a promising method for evaluating the efficacy of cell infusions and has demonstrated the capability for the early detection of response to therapy in real time, an approach that may be of use in wider clinical settings.

Stem cells for liver repopulation

PURPOSE OF REVIEW

The capacity of the liver to regenerate and maintain a constant size despite injury is unique. However, the exact mechanisms are not completely clear. Cell transplantation has been proposed as an alternative treatment of liver diseases. Recent progress has been reported on the generation of stem/progenitor cells that may differentiate toward the hepatic lineage. However, it is currently difficult to determine which of the stem/progenitor cell populations are the best for therapy of a given disease.

RECENT FINDINGS

The limited access to donor human hepatocytes has led to a great interest in the generation of hepatocyte-like cells. Several potential cell sources have been identified. However, general standardization of the methods to evaluate these cells is particularly important for the promise of stem/progenitor-derived hepatocyte-based therapies. Moreover, innovations aimed at improving hepatocyte delivery, survival, and engraftment have recently opened the field of organ engineering that may improve liver repopulation.

SUMMARY

Here we review current evidence reported from the perspective of potential clinical applications of different hepatic cell sources with repopulation capacities and the future perspectives and tools that can facilitate the translation of laboratory work into clinical success.

Hepatocyte transplantation (HTx) corrects selected neurometabolic abnormalities in murine intermediate maple syrup urine disease (iMSUD)

Skvorak et al. [1] demonstrated the therapeutic efficacy of HTx in a murine model of iMSUD, confirming significant metabolic improvement and survival. To determine the effect of HTx on extrahepatic organs, we examined the metabolic effects of HTx in brain from iMSUD animals. Amino acid analysis revealed that HTx corrected increased ornithine, partially corrected depleted glutamine, and revealed a trend toward alloisoleucine correction. For amino acid and monoamine neurotransmitters, decreased GABA was partially corrected with HTx, while the l-histidine dipeptide of GABA, homocarnosine, was decreased in iMSUD mice and hypercorrected following HTx. Elevated branched-chain amino acids (BCAA; leucine, isoleucine, and valine) in MSUD can deplete brain tyrosine and tryptophan (the precursors of monoamine neurotransmitters, dopamine (DA) and serotonin (5-hydroxytryptamine; 5-HT)) through competition via the large neutral amino acid transporter. HTx corrected decreased DA levels and the DA metabolite, 3-methoxytyramine, and partially corrected the DA intermediate 3,4-dihydroxyphenylacetate (DOPAC) and 5-HT levels, despite normal tyrosine and tryptophan levels in iMSUD mouse brain. We further observed enhanced intracellular turnover of both DA and 5-HT in iMSUD mouse brain, both of which partially corrected with HTx. Our results suggest new pathomechanisms of neurotransmitter metabolism in this disorder and support the therapeutic relevance of HTx in iMSUD mice, while providing proof-of-principle that HTx has corrective potential in extrahepatic organs.

The use of stem cells in liver disease

PURPOSE OF REVIEW

Cell transplantation to restore liver function as an alternative to whole liver transplantation has thus far not been successful in humans.

RECENT FINDINGS

Adult mature hepatocytes and various populations of liver progenitors and stem cells are being studied for their regenerative capabilities. Hepatocyte transplantation to treat metabolic deficiencies has shown promising early improvement in liver function; however, long-term success has not been achieved. Liver progenitor cells can now be identified and were shown to be capable to differentiate into a hepatocyte-like phenotype. Despite evidence of mesenchymal stem cell fusion in animal models of liver regeneration, encouraging results were seen in a small group of patients receiving autologous transplantation of CD133 mesenchymal stem cells to repopulate the liver after extensive hepatectomy for liver masses. Ethical issues, availability, potential rejection and limited understanding of the totipotent capabilities of embryonic stem cells are the limitations that prevent their use for restoration of liver function. The effectiveness of embryonic stem cells to support liver function has been proven with their application in the bioartificial liver model in rodents.

SUMMARY

There is ongoing research to restore liver function in cell biology, animal models and clinical trials using mature hepatocytes, liver progenitor cells, mesenchymal stem cells and embryonic stem cells.

22 Levertransplantatie

In 1963 verrichtte Thomas Starzl in Denver de eerste levertransplantatie bij de mens. In 1966 werden in Nederland de eerste twee (auxiliaire, zie par. 22.3.6) levertransplantaties verricht in Leiden en Arnhem, in 1968 startte Cambridge. Helaas resulteerden de eerste levertransplantaties niet in langetermijnoverleving als gevolg van niet-optimale operatietechniek, matige immuunsuppressie en onbekendheid met complicaties.

Liver after Hepatocyte Transplantation for Liver-Based Metabolic Disorders in Children

There are limited data regarding donor hepatocyte engraftment into recipient liver after human hepatocyte transplantation (HHTx). We reviewed the explant livers of seven children with metabolic disorders [ornithine-transcarbamylase deficiency (one), coagulation factor VII deficiency (three), Crigler-Najjar syndrome (one), progressive familial intrahepatic cholestasis type 2 (PFIC-2) deficiency (two)] who received allograft hepatocytes by intraportal infusion with improvement in phenotype, although all later underwent liver transplantation (LT). Immunohistochemistry for bile salt export protein (BSEP) in the PFIC-2 patients and genetic typing following laser capture microdissection (LCM) of liver cells in the others were used to identify donor hepatocytes in recipient explant livers. Explant livers usually showed a preserved lobular architecture. In one patient, hepatocytes were identified inside portal vein thrombi. No donor hepatocytes in liver cell plates were identified immunohistochemically or by genetic typing. HHTx was generally followed by partial recovery of metabolic function; the procedure was well tolerated; any increase in portal vein pressure was transient. Hepatocytes were identified in portal vein thrombi, even months after portal vein infusion. Further studies are needed to monitor donor hepatocytes in vivo, to quantify better the efficacy of the procedure and to find ways of improving engraftment and function.

Cell-based therapies for metabolic liver disease

Liver transplantation is an important therapeutic option for many individuals with metabolic liver disease. Nevertheless, the invasive nature of surgery and limitations of donor organ availability have led to the search for alternatives to whole-organ transplantation. Cell-based therapies have been a particularly active area of investigation in recent years. Hepatocyte transplantations have been performed for a variety of indications, including acute liver failure, end-stage liver disease, and inborn errors of metabolism. Individuals with inborn errors of metabolism who have undergone hepatocyte transplantation have shown clinical improvement and partial correction of the underlying metabolic defect. In most cases, sustained benefits have not been observed. This may be related to inadequate cell dose, variations in the quality of hepatocyte preparations, rejection of the transplanted cells, or senescence of transplanted hepatocytes. Though initial proof of concept with hepatocyte transplantation has been demonstrated by a number of investigators, wide application of this technology has been hindered by the inability to secure a reliable and well-characterized cell source(s) for transplantation and by the challenges of sustained engraftment and expansion of transplanted cells in vivo. Cell-based therapies, including those based on stem cells or more differentiated progenitor cells, may represent the future of cell transplantation for treatment of metabolic liver disease.

Recurrent acute liver failure and mitochondriopathy in a case of Wolcott-Rallison syndrome

A 10-year-old Arabic boy of consanguineous parents has suffered eight episodes of acute liver failure with haemolysis triggered by intercurrent febrile illnesses. The first crisis occurred at 9 months of age, after which diabetes mellitus developed. By the age of 6 years, short stature, mild myopathy and later skeletal epiphyseal dysplasia also became evident. His psychosocial development and educational achievements have remained within normal limits. While there were no clear biochemical indicators of a mitochondrial disorder, an almost complete deficiency of complex I of the respiratory chain was demonstrated in liver but not in fibroblast or muscle samples. Molecular analysis of the eukaryotic translation initiation factor 2alpha kinase gene (EIF2AK3) demonstrated a homozygous mutation, compatible with a diagnosis of Wolcott-Rallison syndrome (WRS). This patient's course adds a new perspective to the presentation of WRS caused by mutations in the EIF2AK3 gene linking it to mitochondrial disorders: recoverable and recurrent acute liver failure. The findings also illustrate the diagnostic difficulty of mitochondrial disease as it cannot be excluded by muscle or skin biopsy in patients presenting with liver disease. The case also further complicates the decision-making process for liver transplantation in cases of acute liver failure in the context of a possible mitochondrial disorder. Such patients may be more likely to recover spontaneously if a mitochondrial disorder underlies the liver failure, yet without neurological features liver transplantation remains an option.