Bioartificial liver treatment prolongs survival and lowers intracranial pressure in pigs with fulminant hepatic failure

Preclinical models of acute liver failure: a comprehensive review

Acute liver failure is marked by the rapid deterioration of liver function in a previously well patient over period of days to weeks. Though relatively rare, it is associated with high morbidity and mortality. This makes it a challenging disease to study clinically, necessitating reliance on preclinical models as means to explore pathophysiology and novel therapies. Preclinical models of acute liver failure are artificial by nature, and generally fall into one of three categories: surgical, pharmacologic or immunogenic. This article reviews preclinical models of acute liver failure and considers their relevance in modeling clinical disease.

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.

Treatment with Bioartificial Liver Improves Lung Injury in a Swine Model of Partial Hepatectomy and Ischemia/Reperfusion

Purpose

Hepatic ischemia/reperfusion injury can lead to remote lung injury by inducing oxidative stress and inflammation. this study aims to investigate whether support of liver function with a bioartificial liver can attenuate remote lung injury after extended hepatectomy.

Methods

Fourteen domestic pigs were subjected to liver ischemia for 150 minutes and 70–75% hepatectomy. Six hours after initiation of hepatic reperfusion the animals were randomly allocated to a 6-hour treatment with a bioartificial liver (group B, n=7) or observation (group C, n=7). Hemodynamic and metabolic parameters were monitored for 24 hours following reperfusion. Lung biopsies were used for histological, nitrotyrosine and mrNA analysis.

Results

Oxygenation gradually deteriorated in group C, but was not significantly impaired in group B. Histological evaluation revealed improvements in alveolar collapse, necrotized pneumonocytes and lymphocyte infiltration in group B. Nitrotyrosine content of the lung was lower in group B compared to group C (55±12 vs. 132±22 nM/mg protein, p<0.01). Lung mRNA expression of interleukin-6, Stat-3 and E-selectin also decreased in group B. Expression of transforming growth factor-α mRNA did not differ between groups.

Conclusions

Application of a bioartificial liver was associated with improvement in several parameters of post-hepatectomy lung injury. the mechanisms appear to involve reduced nitrosative stress and attenuation of the native inflammatory process in the lung.

Adhesion and Function of Rat Liver Cells Adherent to Silk Fibroin/Collagen Blend Films

Collagen is often used in bioartificial livers as a biomimetic coating to promote liver cell adhesion and differentiation. Animal proteins are expensive and expose the host to risks of cross-species infection due to contamination with prions. Silk fibroin (SF) is a biocompatible protein produced by Bombyx mori silk worms and possibly an alternative to collagen. We prepared SF-collagen blend films with different SF content adherent to the bottom of standard tissue culture dishes, and characterized their surface morphology by SEM, their wettability and examined them for their capacity to support rat liver cell adhesion and metabolism. Cell metabolism was characterized by estimating the rate at which cells eliminated ammonia and synthesized urea for up to 48h of culture. SF-containing films were smooth, clear and more wettable than collagen. Cells readily adhered, formed junctions and small size aggregates on all films. As many cells adhered on SF as on collagen films. Cell adhesion to high collagen content blend films could not be reliably estimated because cells dwelt in the large cavities in the film. The effect of SF on cell metabolism differed with the investigated metabolic pathway. However, cells on SF-containing films eliminated ammonia and synthesized urea at rates generally comparable to, for urea synthesis at times higher than, that of cells on collagen. These results suggest that silk fibroin is a suitable substratum for liver cell attachment and culture, and a potential alternative to collagen as a biomimetic coating.

Bioartificial liver attenuates intestinal mucosa injury and gut barrier dysfunction after major hepatectomy: Study in a porcine model

BACKGROUND

The aim of this study was to evaluate whether bioartificial liver support can attenuate gut mucosa injury in a porcine model of posthepatectomy liver dysfunction.

METHODS

Posthepatectomy liver failure was induced in pigs combining major (70%) liver resection and ischemia/reperfusion injury. An ischemic period of 150 minutes was followed by reperfusion for 24 hours. Animals were divided randomly into 2 groups: a control group (n = 6) that received standard critical care and a bioartificial liver support group (Hepat, n = 6) that were subjected to extracorporeal liver support for 6 hours during reperfusion. Intestinal mucosal injury, bacterial translocation, and endotoxin translocation were evaluated in all animals. Intestinal mucosa was also evaluated with markers of oxidative injury and immunohistochemical staining for caspase 3.

RESULTS

When compared with median values, the control group, animals in the Hepat group had a lesser intestinal mucosal injury score (4.0 [range:2.0-5.0] vs 1.0 [range:1.0-2.0]; P < .01), decreased bacterial translocation in the portal and the systemic circulation at 24 hours of reperfusion (P < .05), and decreased portal and systemic endotoxin levels at 24 hours (P < .05). At 24 hours after reperfusion, mucosal protein carbonyls and malondialdehyde levels were decreased in Hepat animals (0.57 nmol/mg [range:0.32-0.70] vs 0.33 nmol/mg [range:0.03-0.53] and 3.85 nmol/mg [range:3.01-6.43] vs 3.27 nmol/mg [range:1.46-3.55], respectively; P < .05). There was no difference in tissue caspase staining.

CONCLUSION

Bioartificial liver support seems to attenuate intestinal mucosal injury and gut barrier dysfunction after major hepatectomy.

Artificial liver support system reduces intracranial pressure more effectively than bioartificial system: an experimental study

OBJECTIVES

Extracorporeal liver support (ELS) may play a role in bridging therapy in patients with acute liver failure (ALF). The aim of this study was to compare the influence of nonbiological and biological methods on intracranial pressure (ICP) in an animal model of ALF.

METHODS

A surgical devascularization model of ALF in pigs (35-40 kg) was used. Elimination therapy started after the onset of hypoglycemia. Biochemical parameters (bilirubin, ammonia, lactate, etc.) as well as ICP and cerebral perfusion pressure (CPP) were monitored for 12 hours. Of the total 31 pigs with ALF, 14 animals were treated by fractionated plasma separation and absorption (FPSA), 10 were treated with a bioartificial liver (BAL), and 7 animals were used as a control group.

RESULTS

FPSA and BAL treatment started on average 3 hours 17 minutes and 2 hours 21 minutes, after devascularization and lasted for 5 hours 54 minutes and 5 hours 43 minutes, respectively. Ammonia levels were lower in the FPSA group, and bilirubin levels differed significantly in both the FPSA and BAL groups compared with controls. However, ICP values were reduced more effectively in pigs treated by FPSA: 19.1 vs. 27.0 mm Hg at 9 hours, 22.5 vs. 28.7 mm Hg at 11 hours, and 24.0 vs. 33.0 mm Hg at 12 hours (p<0.05).

CONCLUSIONS

The artificial liver support system FPSA reduced ICP values more effectively than the Performer O. Liver RanD BAL system. Compared with this BAL system, the nonbiological elimination method of FPSA is a simpler application with the advantage that it can be applied in a more continuous way.

Reversal of experimental posthepatectomy liver failure in pigs: a new application of hepatocyte bioreactors

Postoperative liver failure remains a major cause of morbidity and mortality after extensive hepatectomies. This study aims to evaluate the effectiveness of a hepatocyte bioreactor in the treatment of experimental post-hepatectomy liver failure. Our experimental model included a combination of a side-to-side portacaval shunt, occlusion of the hepatoduodenal ligament for 150 min, 70% hepatectomy, and reperfusion. Following the development of liver failure, 12 pigs were randomized into a control group (n = 6) and a treatment group (n = 6). Both groups underwent extracorporeal perfusion through a plasma separation device, a membrane oxygenator, and two parallel bioreactors. In the latter group, the bioreactors were loaded with 10 billion fresh hepatocytes, isolated from a donor pig. Following hepatocyte treatment, all animals were maintained for 24 h under mechanical ventilation, with intravenous fluid and glucose supplementation. Hemodynamic parameters, intracranial pressure, and biochemical parameters were measured. Liver biopsies were obtained during the 24-h autopsy. The extracorporeal circuit was well-tolerated hemodynamically. Treated animals had lower intracranial pressure compared with controls (at 24 h, 15 ± 3.1 vs. 22 ± 3.5 mm Hg, P = 0.006). Plasma ammonia in treated animals was lower compared with controls at 12 h (100 ± 29 vs. 244 ± 131 µmol, P = 0.026). Liver histological study showed decreased necrosis and increased regeneration activity in treated animals compared with controls. Treatment through an extracorporeal hepatocyte bioreactor attenuates brain edema and improves histological and functional parameters of the liver remnant of pigs with posthepatectomy liver failure.

Future of bioartificial liver support

Many different artificial liver support systems (biological and non-biological) have been developed, tested pre-clinically and some have been applied in clinical trials. Based on theoretical considerations a biological artificial liver (BAL) should be preferred above the non-biological ones. However, clinical application of the BAL is still experimental. Here we try to analyze which hurdles have to be taken before the BAL will become standard equipment in the intensive care unit for patients with acute liver failure or acute deterioration of chronic liver disease.

Iron chelation attenuates intracranial pressure and improves survival in a swine model of acute liver failure

Oxidative mechanisms have been implicated in the pathogenesis of brain edema in acute liver failure (ALF). The aim of this study was to test the hypothesis that inhibition of iron-catalyzed oxidative reactions through iron chelation using deferoxamine could attenuate brain edema in a swine model of ischemic ALF. Following ALF induction (end-to-side portacaval anastomosis and ligation of the hepatoduodenal ligament), 14 animals were randomized to a study group that received an intravenous infusion of 150 mg/kg deferoxamine (group DF; n = 7) or a control group (group C; n = 7). Six sham-operated animals were also assigned to a deferoxamine-treated group (n = 3) or a control group (n = 3). Hemodynamic, neurological, and hematological parameters were monitored postoperatively. All sham animals maintained normal hemodynamics and intracranial pressure. At 18 hours, group DF animals had higher mean arterial pressure (mean +/- standard deviation: 98.0 +/- 15.9 versus 69.9 +/- 15.8 mmHg, P < 0.004), lower intracranial pressure (18.1 +/- 8.6 versus 32.7 +/- 13.4 mmHg, P < 0.032), and higher cerebral perfusion pressure (76.4 +/- 16.4 versus 37.1 +/- 25.6 mmHg, P < 0.006) in comparison with group C. Similar differences were recorded up to the 24th postoperative hour, leading to a significant difference in animal survival (88% in group DF versus 17% in group C, P < 0.001). Furthermore, group DF exhibited an attenuated increase of serum malondialdehyde from the baseline (16% versus 74%, P < 0.05) and lower brain malondialdehyde concentrations (3.7 +/- 1.3 versus 5.7 +/- 2.0 microM/mg of protein, P < 0.05) in comparison with controls. In conclusion, deferoxamine delayed the development of intracranial hypertension and improved survival in pigs with ischemic ALF.

Significant survival prolongation in pigs with fulminant hepatic failure treated with a novel microgravity-based bioartificial liver

The aim of this study was to evaluate the efficacy and safety of our novel Innsbruck Bioartificial Liver (IBAL; US patent no. 10/641275), which contains aggregates of porcine hepatocytes grown under simulated microgravity, in a porcine model of fulminant hepatic failure (FHF). FHF was induced by a combination of 75-80% liver resection and ischemia of the remnant segments for 60 min in 12 pigs. Two experimental groups were studied: the control group (n = 5) received standard intensive care and the study group (n = 5) received IBAL treatment. The survival of pigs with FHF was significantly prolonged by about 150% with IBAL treatment as compared to controls (controls: 20.4 +/- 2.8 h, IBAL: 51.0 +/- 2.2 h; P = 0.00184). In addition, intracranial pressure, blood ammonia, lactate, aspartate aminotransferase, and alkaline phosphatase levels were lower in the IBAL group than in controls, indicating metabolic activity of porcine hepatocytes in the bioreactor. No adverse effects were observed.

A novel plasma filtration therapy for hepatic failure: preclinical studies

There is a need to develop artificial means of liver replacement and/or assistance with the aim of either supporting patients with borderline functional liver cell mass until their liver regenerates, or until a donor liver becomes available for transplantation. Selective plasma filtration is a novel approach to blood purification therapy designed to reduce the level of circulating toxins of hepatic and renal failure, mediators of inflammation and inhibitors of hepatic regeneration. The results of preclinical studies indicate that treatment of pigs with experimentally-induced fulminant hepatic failure is safe and effective in extending survival time and arresting brain swelling. In addition, the amount of ammonia, aromatic amino acids, IL6, TNFalpha and C3a removed during the 6-h treatment in the present study was higher by 34% to 175% than the total plasma content of those substances at the start of therapy.

Features of a newly cloned pig C1 esterase inhibitor

The pig cDNA encoding C1 esterase inhibitor (C1-INH) was isolated and the homology of the sequence was compared with that from other animals. The structure of pig C1-INH contains a two disulfide bridge pattern identical to the human C1-INH. In the amino acid sequence of the first Cys-91 to the C-terminal end, the pigC1-INH has a 76.2% homology with the human protein, and the sequence of the reactive site is close to the human. A surface-bound form of pig and human C1-INH, pC1-INH-PI and hC1-INH, respectively, were next constructed. Stable Chinese hamster ovarian tumor (CHO) cell lines and pig endothelial cell (PEC) lines expressing these C1-INH-PI were prepared by transfection. The basic function and the species specificity of pCI-INH were then investigated using these transfectants. pC1-INH and hC1-INH have almost the same suppressive effect on pig, human, dog and rabbit sera in complement-dependent cell lysis, indicating little species specificity.

Response of porcine hepatocytes in primary culture to plasma from severe viral hepatitis patients

AIM

To observe the effects of plasma from patients with severe viral hepatitis (SVHP) on the growth and metabolism of porcine hepatocytes and the clinical efficiency of bioartificial liver device.

METHODS

Hepatocytes were isolated from male porcines by collagenase perfusion. The synthesis of DNA and total protein, leakages of AST and LDH, changes in glutathione (GSH), catalase and morphology of porcine hepatocytes exposed to SVHP were investigated to indicate the effect of plasma from patients with severe hepatitis on the growth, injury, detoxification, and morphology of porcine hepatocytes.

RESULTS

The synthesis of DNA and protein was inhibited in the medium containing 100% SVHP compared to the controls. The leakages of LDH and AST increased in porcine hepatocytes following exposure to 100% SVHP for 5 h. The difference between 100% SVHP and 10% newborn calf serum (NCS) was significant in t-test (LDH: t = 24.552, P = 0.001; AST: t = 4.169, P = 0.014). After exposure to SVHP for 24 h, alterations in GSH status were significant (F = 2.746, P<0.05) between porcine hepatocytes in 100% SVHP and 10% NCS, but no alteration occurred in the culture medium after 48 h (F = 4.378, P<0.05). A similar profile was observed in catalase activity. Many round vacuoles were observed in porcine hepatocytes cultured in SVHP. The membranes of these cells became indistinct and almost all the cells died on d 5.

CONCLUSION

Plasma from patients with severe hepatitis inhibits the growth, injures membrane, disturbs GSH homeostasis and induces morphological changes of porcine hepatocytes. It is suggested that SVHP should be pretreated to reduce the toxin load and improve the performance of porcine hepatocytes in extracorporeal liver-support devices.

Keeping cool in acute liver failure: rationale for the use of mild hypothermia

Encephalopathy, brain edema and intracranial hypertension are neurological complications responsible for substantial morbidity/mortality in patients with acute liver failure (ALF), where, aside from liver transplantation, there is currently a paucity of effective therapies. Mirroring its cerebro-protective effects in other clinical conditions, the induction of mild hypothermia may provide a potential therapeutic approach to the management of ALF. A solid mechanistic rationale for the use of mild hypothermia is provided by clinical and experimental studies showing its beneficial effects in relation to many of the key factors that determine the development of brain edema and intracranial hypertension in ALF, namely the delivery of ammonia to the brain, the disturbances of brain organic osmolytes and brain extracellular amino acids, cerebro-vascular haemodynamics, brain glucose metabolism, inflammation, subclinical seizure activity and alterations of gene expression. Initial uncontrolled clinical studies of mild hypothermia in patients with ALF suggest that it is an effective, feasible and safe approach. Randomized controlled clinical trials are now needed to adequately assess its efficacy, safety, clinical impact on global outcomes and to provide the guidelines for its use in ALF.

A novel bioartificial liver with culture of porcine hepatocyte aggregates under simulated microgravity

An extracorporeal bioartificial liver device could provide vital support to patients suffering from acute liver failure. We designed a novel, customized bioreactor for use as a bioartificial liver (patent pending). The Innsbruck Bioartificial Liver (IBAL) contains aggregates of porcine hepatocytes grown under simulated microgravity. The culture vessel rotates around its longitudinal axis and is perfused by two independent circuits. The circuit responsible for exchange of plasma components with the patient consists of a dialysis tube winding spirally around the internal wall of the culture vessel. IBAL was evaluated in vitro. Viability tests showed sufficient viability of hepatocytes for up to 10 days. Cytologic examination of samples from the bioreactor showed liver cell aggregates. These were also examined by electron microscopy. A number of biochemical parameters were analyzed. In conclusion, cell culture is possible for at least 10 days in the IBAL system, organoid hepatocyte aggregates are formed and synthetic activity of the hepatocytes was demonstrated.

Heat and Mass Transfer during the Cryopreservation of a Bioartificial Liver Device: A Computational Model

Bioartificial liver devices (BALs) have proven to be an effective bridge to transplantation for cases of acute liver failure. Enabling the long-term storage of these devices using a method such as cryopreservation will ensure their easy off the shelf availability. To date, cryopreservation of liver cells has been attempted for both single cells and sandwich cultures. This study presents the potential of using computational modeling to help develop a cryopreservation protocol for storing the three dimensional BAL: Hepatassist. The focus is upon determining the thermal and concentration profiles as the BAL is cooled from 37 degrees C-100 degrees C, and is completed in two steps: a cryoprotectant loading step and a phase change step. The results indicate that, for the loading step, mass transfer controls the duration of the protocol, whereas for the phase change step, when mass transfer is assumed negligible, the latent heat released during freezing is the control factor. The cryoprotocol that is ultimately proposed considers time, cooling rate, and the temperature gradients that the cellular space is exposed to during cooling. To our knowledge, this study is the first reported effort toward designing an effective protocol for the cryopreservation of a three-dimensional BAL device.

Cryopreservation of isolated primary rat hepatocytes: enhanced survival and long-term hepatospecific function

OBJECTIVE

To investigate the long-term effect of cryopreservation on hepatocyte function, as well as attempt to improve cell viability and function through the utilization of the hypothermic preservation solution, HypoThermosol (HTS), as the carrier solution.

SUMMARY BACKGROUND DATA

Advances in the field of bioartificial liver support have led to an increasing demand for successful, efficient means of cryopreservation of hepatocytes.

METHODS

Fresh rat hepatocytes were cryopreserved in suspension in culture media (Media-cryo group) or HTS (HTS-cryo group), both supplemented with 10% DMSO. Following storage up to 2 months in liquid nitrogen, cells were thawed and maintained in a double collagen gel culture for 14 days. Hepatocyte yield and viability were assessed up to 14 days postthaw. Serial measurements of albumin secretion, urea synthesis, deethylation of ethoxyresorufin (CYT P450 activity), and responsiveness to stimulation with interleukin-6 (IL-6) were performed.

RESULTS

Immediate postthaw viability was 60% in Media-cryo and 79% in HTS-cryo, in comparison with control (90%). Albumin secretion, urea synthesis and CYT P450 activity yielded 33%, 55%, and 59% in Media-cryo and 71%, 80%, and 88% in HTS-cryo, respectively, compared with control (100%). Assessment of cellular response to IL-6 following cryopreservation revealed a similar pattern of up-regulation in fibrinogen production and suppression of albumin secretion compared with nonfrozen controls.

CONCLUSIONS

This study demonstrates that isolated rat hepatocytes cryopreserved using HTS showed high viability, long-term hepatospecific function, and response to cytokine challenge. These results may represent an important step forward to the utilization of cryopreserved isolated hepatocytes in bioartificial liver devices.

The immobilization of hepatocytes on 24 nm-sized gold colloid for enhanced hepatocytes proliferation

Bioartificial liver and hepatocyte transplantation is anticipated to supply a temporary metabolic support for candidates of liver transplantation or for patients with fulminant liver failure. An essential restriction of this form is the inability to acquire an enough amount of hepatocytes. Enhancement of the proliferation and differentiated function of hepatocytes is becoming a pursued target. Here, porcine hepatocytes were successfully immobilized on nano-sized gold colloid particles to construct a "hepatocyte/gold colloid" interface at which hepatocytes can be quickly proliferated. The properties of this resulting interface were characterized and confirmed by scanning electron microscopy and atomic force microscopy. The proliferative mechanism of hepatocytes was also discussed. The proliferated hepatocytes could be applied to the clinic based on their excellent functions for the synthesis of protein, glucose and urea as well as lower lactate dehydrogenase release.

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.

Cryopreservation and gel collagen culture of porcine hepatocytes

AIM: To study the method of cryopreserving porcine hepatocytes and gel collagen culture measure after its cryopreservation.

METHODS: Hepatocytes, isolated from Chinese experimental suckling mini-pigs by two-step perfusion with collagenase using an extra corporeal perfusion apparatus, were cryopreserved with 50 mL/L to 200 mL/L DMSO in liquid nitrogen for 4 mo, then thawed and seeded in 1 or between 2 layers of gel collagen. The expression of porcine albumin message RNA, cellular morphology and content of aspartate aminotransferase (AST) and urea nitrogen (UN) were examined during culture in gel.

RESULTS: Viability of 150 mL/L DMSO group thawed hepatocytes was (83 ± 4)%, but after purification, its viability was (90 ± 5)%, attachment efficiency was (86 ± 7)%, the viability of thawed hepatocytes was near to fresh cells. When the thawed hepatocytes were cultivated in gel collagen with culture medium adding epidermal growth factor, the hepatocytes grew in various administrative levels in mixed collagen gel, and bunchy in the sandwich configuration cultures. For up to 10 days’ culture, the typical cellular morphological characteristics of cultivated hepatocytes could be observed. The leakage of AST was lower during culture in gel than that in common culture. At the same time, the UN synthesized by cells cultivated in mixed gel collagen was higher than that in other groups.

CONCLUSION: Storage in liquid nitrogen can long keep hepatocytes’ activities, the concentration of 150 mL/L DMSO is fit for porcine hepatocytes’ cryopreservation. Thawed hepatocytes can be cultivated with collagenous matrix, which provides an environment that more closely resembles that in vivo and maintain the expression of certain liver-specific function of hepatocytes.

Bioartificial liver inoculated with porcine hepatocyte spheroids for treatment of canine acute liver failure model

The aim of this study was to evaluate a novel bioartificial system in a canine model of acute liver failure. An acute liver failure model in canines was induced by an end-side portocaval shunt combined with common bile duct ligation and transection. The bioartificial liver system, which utilized blood perfusion through a hollow fiber bioreactor from BIOLIV A3A inoculated with 1.0 - 3.1 x 1010 porcine hepatocyte spheroids, was developed for the treatment of acute liver failure. Sixteen acute liver failure model canines were divided between a group treated with bioartificial liver (n=8) and a control group (n=8) for 5 h. Blood alanine aminotransferase (ALT), alkaline phosphatase (AKP), total bilirubin (TBi), direct bilirubin (DBi), prothrombin time (PT), ammonia levels, and the ratio of branched chain to aromatic amino acids (Fischer's ratio) were determined. ALT, AKP, TBi, DBi, and ammonia levels were significantly elevated, PT was significantly prolonged, and Fischer's ratio decreased significantly in the canine model of the two groups on day 14 after operation compared to baseline. There were no significant differences between the two groups in laboratory data before treatment. In canines treated with the bioartificial liver system, ALT, AKP, TBi, DBi, and ammonia levels decreased significantly, PT was significantly shortened, Fischer's ratio was significantly elevated after treatment, and the survival rate by day 7 after treatment was 100%. In canines in the control group, on the other hand, there were no significant differences in ALT, AKP, TBi, DBi, PT, and ammonia levels between pretreatment and posttreatment, though these indices decreased to a slight degree after treatment. The survival rate by day 7 after treatment was 62.5% in the control group. Fischer's ratio decreased after treatment. ALT, AKP, TBi, DBi, PT, and ammonia levels in the bioartificial liver system group were lower, and Fischer's ratio and survival rate were higher than those in the control group after treatment. These results indicate that the novel bioartificial liver system we developed has a significant impact on the course of canine acute liver failure model and has potential advantages for clinical use in patients with acute liver failure.

Early experiences with a porcine hepatocyte-based bioartificial liver in acute hepatic failure patients

Orthotopic liver transplantation (OLT) is the only effective therapeutic modality in severe acute hepatic failure (AHF). The scarcity of organs for transplantation leads to an urgent necessity for temporary liver support treatments in AHF patients. A hepatocyte-based bioartificial liver (BAL) is under investigation with the main purpose to serve as bridging treatment until a liver becomes available for OLT, or to promote spontaneous liver regeneration. We developed a novel radial-flow bioreactor (RFB) for three-dimensional, high-density hepatocyte culture and an integrated pumping apparatus in which, after plasmapheresis, the patient's plasma is recirculated through the hepatocyte-filled RFB. Two hundred thirty grams of freshly isolated porcine hepatocytes were loaded into the RFB for clinical liver support treatment. The BAL system was used 8 times in supporting 7 AHF patients in grade III-IV coma, all waiting for an urgent OLT Three patients with no history of previous liver diseases were affected by fulminant hepatic failure (FHF) due to hepatitis B virus, 3 by primary non-function (PNF) of the transplanted liver, and one by AHF due to previous abdominal trauma and liver surgery. Six out of 7 patients underwent OLT following BAL treatment(s), which lasted 6-24 hours. All patients tolerated the procedures well, as shown by an improvement in the level of encephalopathy, a decrease in serum ammonia, transaminases and an amelioration of the prothrombin time, with full neurological recovery after OLT Our initial clinical experience confirms the safety of this BAL configuration and suggests its clinical efficacy as a temporary liver support system in AHF patients.