Development of a bioartificial liver with sandwiched-cultured hepatocytes between two collagen gel layers.

We have been developing a multiplate type of bioartificial liver (BAL) using primary cultured hepatocyte monolayers since 1987. This BAL has been shown to prolong the survival time of anhepatic dogs and rabbits. Initially, hepatocytes were cultivated on collagen-coated plates. To increase the multiplated BAL function, a sandwich cultivation method was employed in which rat hepatocytes were cultured between two collagen gel layers and were then evaluated in both stationary and perfusion cultures. In the stationary culture, the sandwich method showed a higher activity in urea synthesis than in the other culture methods (culture on a collagen coating, culture on a collagen gel, and culture between a collagen coating and a collagen gel) for 14 days. In the perfusion culture, a BAL housing cultured hepatocytes (6.5 x 10(7) cells) in the sandwich system showed urea synthesis activity ranging from 17.5 to 22.6 micrograms/2 x 10(6) cells/90 min. This activity was maintained for 5 days in the perfusion culture. The sandwich type of cultivation is applicable to the multiplated BAL.