Biomedical subjects

R A F M Chamuleau

Publications and source records attributed to R A F M Chamuleau.

10 recordsLinked to original sources

PubMed2006

Subnormothermic preservation maintains viability and function in a porcine hepatocyte culture model simulating bioreactor transport.

Bioartificial liver (BAL) systems have been developed to bridge patients with acute liver failure (ALF) to liver transplantation or liver regeneration. Clinical application of BAL systems is dependent on the supportive quality of cells used and direct availability of the whole system. Reliable transport of BAL systems from the laboratory to remote treatment centers is therefore inevitable. Subsequently, preservation conditions play a crucial role during transport of a BAL, with temperature being one of the most determining factors. In this study, we assessed the effect of subnormothermic preservation on freshly isolated porcine hepatocytes cultured in monolayer under oxygenation. Additionally, the effect of the University of Wisconsin (UW) preservation solution was compared with Williams' E (WE) culture medium at 4 degrees C. The control group was cultured for 3 days at 37 degrees C, whereas the transport groups were cultured at 4 degrees C, 15 degrees C, 21 degrees C, or 28 degrees C for 24 h at day 2. All groups were tested each day for cell damage and hepatic functions. Subnormothermic culture (i.e., 15 degrees C to 28 degrees C) for a period of 24 h did not reduce any hepatic function and did not increase cellular damage. In contrast, culture of hepatocytes in WE medium and preservation in UW solution at 4 degrees C significantly reduced hepatic function. In conclusion, freshly isolated porcine hepatocytes can be preserved for 24 h at subnormothermic temperatures as low as 15 degrees C. Future research will focus on the implementation of the AMC-BAL in an oxygenated culture medium perfusion system for transport between the laboratory and the hospital.

Albumins↗

PubMed2005

Liver support therapy: an overview of the AMC-bioartificial liver research.

Acute liver failure (ALF) is a disease with a mortality of 60-90% depending on the cause. Only high-urgency liver transplantation is able to increase survival compared to standard intensive care therapy. Liver transplantation is hampered by the increasing shortage of organ donors, resulting in a high incidence of patients with ALF dying on the transplantation waiting list. Amongst a variety of liver assist therapies, bioartificial liver (BAL) therapy is marked as the most promising solution to bridge ALF patients to liver transplantation or to liver regeneration, since several BAL systems showed significant improvement of survival time in experimental animals with irreversible ALF. One of these systems has been developed at the Academic Medical Center in Amsterdam, The Netherlands - the AMC-BAL. This overview describes the development of the AMC-BAL based on porcine hepatocytes which was started 10 years ago. Positive results of in-vitro functionality and in vivo safety and efficacy led to a successful phase I study in 12 ALF patients in Italy. However, xenotransplantation legislation in many European countries prohibits the use of porcine hepatocytes in clinically applied BAL systems. The future of the BAL, therefore, resides in the development of a human-derived hepatocyte cell line as biocomponent of BAL systems.

Animals↗

PubMed2005

['Artificial support in case of hepatic failure'; a report from the Dutch Health Council].

Acute liver failure has a high mortality (40-95%) depending on the cause. Emergency liver transplantation is the only way to improve survival: a one-year survival of 5o-6o%. In the past, many different modalities of artificial liver support have been studied. None of them appeared to be able to improve survival compared to maximal intensive care treatment. Two rather recent approaches are the development of a bioartificial liver (BAL), charged with billions of porcine liver cells, and albumin dialysis (MARS). A signalling report has been sent to the Dutch Minister of Health to resume the current position of BAL and MARS in the treatment of severe liver failure. The outcome is that no firm conclusions can yet be drawn as to the applicability of these modalities. Only two small-scale controlled clinical trials have been published on the MARS technique and the only published large-scale controlled clinical trial of a BAL in acute liver failure is not conclusive. On theoretical grounds, BAL treatment has more potential than MARS since a BAL will replace not only the failing hepatic detoxification but also the synthetic and metabolic functions. So far, no evidence has been found for transmission ofporcine pathogens to patients despite numerous phase 1 studies of bioartificial livers charged with porcine hepatocytes. More well-designed controlled clinical trials are needed. Therefore, the Dutch moratorium on xenotransplantation should be revised.

Albumins↗

PubMed2005

Outcome of regional and local ablative therapies for hepatocellular carcinoma: a collective review.

BACKGROUND: Transcatheter arterial (chemo) embolization (TACE), cryoablation (CA) and percutaneous ethanol injection (PEI) were the first regional and local ablative techniques that came into use for irresectable HCC. Radiofrequency ablation (RFA) and interstitial laser coagulation (ILC) followed and have now evolved rapidly. It would not be ethical to compare resection with ablation in patients well enough to undergo major surgery. Therefore, hepatic resection and hepatic transplantation remain the only curative treatment options for HCC. METHODS: On the basis of a Medline literature search and the authors' experiences, the principles, current status and prospects of TACE and local ablative techniques in HCC are reviewed. RESULTS: Complete tumour necrosis can be achieved in 60-100% of patients treated with PEI (70-100%), cryoablation (60-85%), RFA (80-90%) or ILC (70-97%). After TACE significant tumour response is achieved in 17-61.9% but complete tumour response is rare (0-4.8%) as viable tumour cells remain after TACE. Five-year survival rates are available for TACE (1-8%), PEI (0-70%) and cryoablation (40%). Only PEI and RFA were compared in one RCT. RFA was associated with fewer treatment sessions and a higher complete necrosis rate. Furthermore, all techniques are associated with low morbidity and mortality, but cryoablation seems to be associated with a higher morbidity rate. CONCLUSION: TACE has shown to be a valuable therapy with survival benefits in strictly selected patients with unresectable HCC. RFA and PEI are now considered as the local ablative techniques of choice for the treatment of, preferably small, HCC. When tumours are located close to bile ducts or large vessels, PEI remains a valuable therapy. Completeness of ablation can be more easily monitored during cryoablation and another advantage of cryoablation is the possibility of edge freezing. The results of ILC are comparable to RFA with only few side effects and high tumour response rates.

Carcinoma, Hepatocellular↗

PubMed2005

Assessment and improvement of liver specific function of the AMC-bioartificial liver.

UNLABELLED: The variety of methods for measuring bioactive mass and functionality of bioartificial livers (BAL) is confusing and prevents accurate comparison of reported data. Here we present a comparison of different hepatocyte quantification methods and propose that estimation of cell pellet volume after centrifugation generates a reliable, useful and fast method. In addition a correlation is made between several function tests performed in 26 bioreactors to assess their predictive value. The ammonia eliminating capacity was found to be most predictive for other liver functions, except for lidocaine elimination as a measure of mixed function oxidase activity, which should therefore be determined separately. The oxygen consumption test proved to be an easy and predictive parameter as well. The first generation of our BAL system needed further development to assure optimal treatment of acute liver failure (ALF) patients. Changes in the porcine hepatocyte isolation method and bioreactor loading as well as changes in bioreactor configuration, including use of different materials, resulted in a significantly improved level and maintenance of in vitro BAL function. A fourfold increase in ammonia eliminating capacity, which is only reduced to 75% after seven days of culturing, offers promising prospects for further clinical application. CONCLUSION: The current second generation of our BAL and improvement of hepatocyte isolation and testing protocols have led to a significant increase in the level as well as the maintenance of hepatocyte specific function in our BAL. Finally, consensus on definition of the bioactive mass to be loaded in the bioreactor and insight in the variation and reliability of the functional and metabolic parameters enhances comparison of the different types of bioartificial livers presented in literature.

Ammonia↗

PubMed2004

Large animal models of fulminant hepatic failure in artificial and bioartificial liver support research.

Among the large range of organs involved in the field of tissue engineering (skin, blood vessels, cartilage, etc.) the liver has been given broad attention in the last decade. Liver support systems encompassing artificial and bioartificial systems are applied to treat patients with fulminant hepatic failure (FHF) as a bridge to orthotopic liver transplantation or to liver regeneration. To test safety, technical applicability and therapeutic effect of liver support systems, reliable animal models are needed. Due to the complexity of FHF many diverse attempts have been made to develop an adequate animal model to study liver failure, liver regeneration and liver support systems. In this paper an overview is given of the different models and their advantages and disadvantages are discussed. Suggestions are made for the most suitable large animal model to test liver support systems.

Acetaminophen↗

PubMed2003

Blood coagulation in anhepatic pigs: effects of treatment with the AMC-bioartificial liver.

The function of a newly devised bioartificial liver (AMC-BAL) based on viable, freshly isolated porcine hepatocytes has been evaluated in anhepatic pigs. The aim of this study was to assess the contribution of BAL treatment on blood coagulation parameters. Pigs were anesthetized and a total hepatectomy was performed (n = 15). The infrahepatic caval vein and the portal vein were connected to the subdiaphragmatic caval vein using a three-way prosthesis. Animals received standard intensive care (control, n= 5), treatment with an empty BAL (device control, n= 5) or with a cell-loaded BAL (BAL-treatment, n= 5) for a period of 24 h starting 24 h after hepatectomy. Coagulation parameters studied concerned prothrombin time (PT), platelet count, the procoagulant system (factors (F)II, FV, FVII, FVIII and fibrinogen), anticoagulant system (AT III), fibrinolytic system (t-PA, PAI-1) as well as markers of coagulation factor activation (TAT complexes, prothrombin fragment F1 + 2). FII, FV, FVII, AT III and fibrinogen rapidly decreased after total hepatectomy in pigs in accordance with the anhepatic state of the animals. FVIII levels were not influenced by the hepatectomy. A mild drop in platelet count was seen in all groups. Treatment of anhepatic pigs with the cell-loaded BAL did not restore PT or clotting factor levels. TAT and F1 + 2 complexes, however, were significantly increased in this group. Levels of t-PA and PAI-1 were not influenced by cell-loaded BAL treatment. Treatment of anhepatic pigs with the AMC-BAL based on freshly isolated porcine hepatocytes does not result in an improved coagulation state due to extensive consumption of clotting factors. However, increased levels of TAT complexes and prothrombin fragments F1 + 2 during treatment of anhepatic pigs indicate synthesis and direct activation of coagulation factors, leading to thrombin generation. This demonstrates that this bioartificial liver is capable of synthesizing coagulation factors.

Animals↗

PubMed2002

Recent developments on human cell lines for the bioartificial liver.

Most bioartificial liver (BAL) devices contain porcine primary hepatocytes as their biological component. However, alternatives are needed due to xenotransplantation associated risks. Human liver cell lines have excellent growth characteristics and are therefore candidates for application in BAL devices. Tumour-derived cell lines HepG2 and C3A express a variety of liver functions, but some specific liver functions, like ammonia detoxification and ureagenesis are insufficient. Immortalised human hepatocytes might offer better prospects. The balance between immortalisation and transformation with dedifferentiation of cells seems controllable by conditional immortalisation and/or the use of telomerase as immortalising agent. Another promising approach will be the use of embryonic or adult human stem cells. Rodent stem cells have been directed to hepatic differentiation in vitro, which might be applicable to human stem cells. However, both functionality and safety of immortalised human liver cell lines and differentiated stem cells should be improved before successful use in BAL devices becomes reality.

Animals↗

PubMed2002

Phase I clinical trial with the AMC-bioartificial liver.

UNLABELLED: Recently a bio-artificial liver (BAL) system has been developed at the Academic Medical Center (AMC) of Amsterdam to bridge patients with acute liver failure (ALF) to orthotopic liver transplantation (OLT). After successful testing of the AMC-BAL in rodents and pigs with ALF, a phase I study in ALF patients waiting for (OLT) was started in Italy. We present the safety outcome of the first 7 patients aged 21-56 years with coma grade III or IV The total AMC-BAL treatment time ranged from 8 to 35 hours. Three patients received 2 treatments with two different BAL's within three days. Six of the 7 patients were successfully bridged to OLT. One patient showed improved liver function after two treatments and did not need OLT. No severe adverse events of the BAL treatment were noted. CONCLUSION: Treatment of ALF patients with the AMC-BAL is a safe and feasible technique to bridge the waiting time for an adequate liver-graft.

Adult↗

PubMed2002

Treatment of acute liver failure in pigs reduces hepatocyte function in a bioartificial liver support system.

Several different types of bioartificial liver (BAL) support systems have been developed to bridge patients suffering from acute liver failure (ALF) to transplantation or liver regeneration. In this study we assessed the effects of ALF plasma on hepatocyte function in the BAL system that has been developed in our center. Pigs (40-60 kg) were anaesthetised and a total hepatectomy was performed. Cells were isolated from the resected livers and were transferred to the bioreactor of the BAL system. Twenty hours after cell isolation, hepatocytes in the BAL were tested for cell viability and functional activity by using a recirculating test medium in which assessment of LDH leakage, ammonia clearance, urea synthesis, 7-ethoxycoumarin O-deethylase (ECOD) activity and pseudocholine esterase production was performed. Subsequently, two groups were studied. In one group (I, n=5), the cell-loaded bioreactor was used to treat the donor pig, rendered anhepatic, for 24 hours. In the second group (II, n=5) the bioreactor was cultured for 24 h and served as a control. After 24 hours treatment or culturing, the cell viability count and functional activity tests were repeated. The results show that hepatocytes in the BAL remained viable after 24 h treatment of anhepatic pigs, as shown by the LDH release and pseudocholine esterase production. However, metabolic functions such as ammonia clearance, ECOD and urea synthesis were reduced after 24 h exposure of hepatocytes to autologous ALF plasma, whereas these functions were unaltered after 24 h culturing of the cells in the bioreactor.

7-Alkoxycoumarin O-Dealkylase↗