Is the biological artificial liver clinically applicable? A historic review of biological artificial liver support systems.

Hemoperfusion, hemodiafiltration, plasma exchange, and extracorporeal liver perfusion have already been adopted to treat patients with acute and chronic hepatic failure. However, the survival rate of patients with acute hepatic failure remains at approximately 30% and has not improved as expected. Current advances in biotechnology have opened the way for the development of a biological artificial liver, which is called the hybrid artificial liver because it consists of both biological and artificial materials. Isolated hepatocytes have been investigated for use in various types of hybrid artificial liver. In addition, the role of biomatrices, microcarriers, and the microencapsulation technique has been studied with respect to long-term maintenance of hepatocellular function and development of high-density culture systems for hepatocytes. Before clinical application of hybrid artificial liver support systems becomes possible, many problems have to be resolved, including large-scale preparation and long-term preservation of biomaterials, high-density and stable immobilization of biomaterials on artificial materials, control of immunological hazards, biocompatibility, safe transportation and sterilization of biomaterials, and the high cost. We review the history of biological artificial livers and discuss their future role.