Liver failure is a serious problem that affects thousands of people in the United States each gear. Other than liver transplantation, a supportive therapy has been unavailable for patients with liver failure that is refractory to medical treatment. An apparent solution to this problem is a hepatocyte liver-assist system. Such a system is composed of mammalian hepatocytes loaded in a mechanical apparatus, such as a hollow fiber cartridge. During extracorporeal perfusion of the system, the hepatocytes provide metabolic function to the patient with liver failure. At least two extracorporeal hepatocyte systems hare shown promise in human clinical trials of acute liver failure. In fact, one system has gained approval from the Food and Drug Administration for testing in a randomized multicenter clinical trial. In this article, key issues of clinical testing are reviewed, and major contributions and questions that remain unresolved are emphasized.
