In vitro evaluation of a novel bioreactor based on an integral oxygenator and a spirally wound nonwoven polyester matrix for hepatocyte culture as small aggregates

BACKGROUND/AIMS: The development of custom-made bioreactors for use as a bioartificial liver (BAL) is considered to be one of the last challenges on the road to successful temporary extracorporeal liver support therapy. We devised a novel bioreactor (patent pending) which allows individual perfusion of high density cultured hepatocytes with low diffusional gradients, thereby more closely resembling the conditions in the intact liver lobuli. METHODS: The bioreactor consists of a spirally wound nonwoven polyester matrix, i.e. a sheet-shaped, three-dimensional framework for hepatocyte immobilization and aggregation, and of integrated hydrophobic hollow-fiber membranes for decentralized oxygen supply and CO2 removal. Medium (plasma in vivo) was perfused through the extrafiber space and therefore in direct hepatocyte contact. Various parameters were assessed over a period of 4 days including galactose elimination, urea synthesis, lidocaine elimination, lactate/pyruvate ratios, amino acid metabolism, pH, the last day being reserved exclusively for determination of protein secretion. RESULTS: Microscopic examination of the hepatocytes revealed cytoarchitectural characteristics as found in vivo. The biochemical performance of the bioreactor remained stable over the investigated period. The urea synthesizing capacity of hepatocytes in the bioreactor was twice that of hepatocytes in monolayer cultures. Flow sensitive magnetic resonance imaging (MRI) revealed that the bioreactor construction ensured medium flow through all parts of the device irrespective of its size. CONCLUSIONS: The novel bioreactor showed encouraging efficiency. The device is easy to manufacture with scale-up to the liver mass required for possible short-term support of patients in hepatic failur

Evaluation of a novel bioartificial liver in rats with complete liver ischemia: treatment efficacy and species-specific alpha-GST detection to monitor hepatocyte viability

BACKGROUND/AIMS: There is an urgent need for an effective bioartificial liver system to bridge patients with fulminant hepatic failure to liver transplantation or to regeneration of their own liver. Recently, we proposed a bioreactor with a novel design for use as a bioartificial liver (BAL). The reactor comprises a spirally wound nonwoven polyester fabric in which hepatocytes are cultured (40 x 10(6) cells/ml) as small aggregates and homogeneously distributed oxygenation tubing for decentralized oxygen supply and CO2 removal. The aims of this study were to evaluate the treatment efficacy of our original porcine hepatocyte-based BAL in rats with fulminant hepatic failure due to liver ischemia (LIS) and to monitor the viability of the porcine hepatocytes in the bioreactor during treatment. The latter aim is novel and was accomplished by applying a new species-specific enzyme immunoassay (EIA) for the determination of porcine alpha-glutathione S-transferase (alpha-GST), a marker for hepatocellular damage. METHODS: Three experimental groups were studied: the first control group (LIS Control, n = 13) received a glucose infusion only; a second control group (LIS No-Cell-BAL, n = 8) received BAL treatment without cells; and the treated group (LIS Cell-BAL, n = 8) was connected to our BAL which had been seeded with 4.4 x 10(8) viable primary porcine hepatocytes. RESULTS/CONCLUSIONS: In contrast to previous comparable studies, BAL treatment significantly improved survival time in recipients with LIS. In addition, the onset of hepatic encephalopathy was significantly delayed and the mean arterial blood pressure significantly improved. Significantly lower levels of ammonia and lactate in the LIS Cell-BAL group indicated that the porcine hepatocytes in the bioreactor were metabolically activity. Low pig alpha-GST levels suggested that our bioreactor was capable of maintaining hepatocyte viability during treatment. These results provide a rationale for a comparable study in LIS-pigs as a next step towards potential clinical application