54. Performance of rat liver microorgans (lmos) cold preserved in BG35 solution as the biological component of a new flat-plate model of bioartificial liver (BAL)

BAL devices constitute an innovative therapeutic approach currently accepted as a bridge to liver transplantation for patients with liver failure. Usually, the patient’s blood or plasma is circulated extra-corporeally through a bioreactor that houses a metabolically active component which performs the functions of the damaged liver. Among these, ammonia detoxification is crucial because the accumulation of this metabolite is highly toxic to the central nervous system. Our first BAL prototype consisted of a hollow fiber-based cartridge perfused with goat blood through the fiber’s lumen. This device showed an effective ammonia depuration rate using isolated hepatocytes as cellular component. But, since the “ideal” biological component should contain all liver cell types for a maximum response, we became interested in evaluating LMOs: tissue slices that retain the basic micro architecture of the liver lobe. Therefore, we built up a flat-based BAL model, suitable to use fresh or cold preserved LMOs. Accordingly, we reported the development of a novel preservation solution (BG35) that showed the same efficacy as ViaSpan® to protect LMOs against cold preservation injury for 48h. So, the aim of the present work was to evaluate the performance of cold preserved rat LMOs in our new BAL model. LMOs were manually cut from rat livers (338±27μm thickness, n=25) and stored in BG35 or ViaSpan® solutions at 0°C up to 48h of preservation. Freshly cut LMOs were used as controls. After the preservation period, 1.5g of LMOs was loaded into the BAL and an ammonia overload (1.06±0.12mM, n=9) was added to the blood before initiating the system perfusion at 9mL/min (blood volume=35mL). Samples of blood and extra-fiber fluid were taken after 60 and 120min of perfusion. We determined LDH release (%) by LMOs in the extra-fiber fluid and ammonia detoxification capacity (% of the initial dose detoxified at different times) in the perfusing blood. After 120min of perfusion, LMOs cold preserved in BG35 or ViaSpan® were able to detoxify 57.4±12.1 % and 51.9±6.0 %, respectively, of the initial ammonia overload (n=3). No significant differences were found with Controls (49.3±8.8%, n=3). All groups showed a good maintenance of their viability: LDH release after 120min was 10.5±5.4 % and 9.2±3.4% for BG35 and ViaSpan® preserved LMOs, respectively, similar to Controls (6.1±2.2%, n=3). In conclusion, LMOs cold preserved in both solutions showed a good ammonia detoxification capacity that enables their use as biological component of a BAL device. These results confirm that the BG35 is as efficient as ViaSpan® to protect rat LMOs against cold preservation injury and it is considerably less expensive and easy to prepare. Also, these experiments show that the BAL prototype developed constitutes a simple and inexpensive tool to investigate the effects of preservation, cryopreservation, or culture on the LMOs functions.