Membrane-Based Bioartificial Liver Devices

Liver disease and the subsequent loss of liver function is an enormous clinical challenge, and is currently the 12th most frequent cause of death in the United States and the 4th most frequent for middle-aged adults [Mann et al., 2003]. Emergence of new liver diseases such as steatohepatitis, absence of a hepatitis C vaccine, and increasing number of hepatocellular carcinoma patients, further worsens the situation [Bosch et al., 2004; Jemal et al., 2010]. Liver transplantation is the only established successful treatment for end-stage liver disease, and currently there are over 120,000 people on the waiting list for a donor organ and of those, there are around 15,000 candidates awaiting a liver transplant (based on United Network for Organ Sharing Organ Procurement and Transplantation Network, UNOS OPTN, January 2016). In 2015, there were 5950 liver transplants performed in the United States. Various surgical options have been pursued, including living-donor partial transplantation and split liver transplants, in order to expand the supply of livers available for transplantation [Clavien et al., 2007]. Despite these surgical advances, organ shortage remains a major hurdle, thus it is unlikely that liver transplantation procedures alone will ever meet the increasing demand. For these reasons, many researchers have developed various extracorporeal biohybrid artificial liver (BAL) systems. Generally, a BAL system consists of functional liver cells supported by an artificial cell culture material. In particular, it incorporates hepatocytes into a bioreactor in which the cells are immobilized, cultured, and induced to perform the hepatic functions by processing the blood or plasma of liver-failure patients. BAL devices act as a bridge for the patients until a donor organ is available for transplantation or until liver regeneration [Strain et al., 2002].