Transplanted cryopreserved encapsulated porcine hepatocytes are as effective as fresh hepatocytes in preventing death from acute liver failure in rats

BACKGROUND: An implantable bioartificial liver (BAL) using xenogeneic isolated hepatocytes may be an alternative method to orthotopic liver transplantation for treatment of acute liver failure. The purpose of this study was to demonstrate that not only fresh but also cryopreserved porcine hepatocytes could be used in a BAL to prevent death after the onset of acute liver failure in rats. METHODS: Acute liver failure was induced by two-stage 95% hepatectomy. At the time of completion of liver resection, 100 rats were assigned to undergo or not undergo transplantation into the peritoneum of 4 meters of hollow fibers filled with 60 million either fresh or cryopreserved porcine hepatocytes, or syngeneic hepatocytes, or culture medium, or of 60 million nonencapsulated cryopreserved porcine hepatocytes without immunosuppressive therapy. Survival rates at 7 days were compared between the different groups. RESULTS: In the control groups of hepatectomized animals not receiving encapsulated hepatocytes, 69-79% of the rats died from acute liver failure. The mortality rate was reduced to 15% (2 of 13) in rats receiving fresh porcine hepatocytes (P<0.01), 25% (4 of 16) in rats transplanted with either cryopreserved or syngeneic hepatocytes (P<0.05). Survival rates were maintained when hollow fibers were explanted > or =4 days after hepatectomy. In surviving rats, the weight of the remnant native liver increased with time and returned to the initial weight after 1 month. CONCLUSIONS: The implantable BAL using xenogeneic porcine hepatocytes was able in preventing death from acute liver failure without immunosuppressive therapy. Encapsulated cryopreserved hepatocytes were as effective as fresh hepatocytes.