In vitro functional assenssment of bioartificial liver system using immobilized porcine hepatocyte spheroids

To treat fulminant hepatic failure (FHF) patients, various extracorporeal bioartificial liver (BAL) systems have been developed. Several requirements should be met for the development of BAL systems: hepatocytes should be cultured in a sufficiently high density; their metabolic functions should be of a sufficiently high level and duration; and the BAL systems module should permit scaling-up and aseptic handling. Several investigators have found that freshly isolated primary hepatocytes can be cultured into three dimensional, tightly packed, freely suspended, multicellular aggregates, or spheroids. These specialized cell structures exhibited enhanced liver specific functions and a prolonged differentiated state compared to cells maintained in a monolayer culture. Cells in spheroids appear to mimic the morphology and ultrastructure of the in vivo liver lobule. The ability of hepatocytes to organize into three-dimensional structures was hypothesized to contribute to their enhanced liver-specific activities. In this study, the ammonia removal rate and urea secretion rate of pig hepatocytes spheroids encapsulated in Ca-alginate bead were determined. A packed-bed bioreactor with encapsulated pig hepatocytes was devised as BAL support system. The efficacy of the system was evaluated in vitro.