FUNCTIONAL STABILITY OF PORCINE HEPATOCYTE SPHEROIDS IN VARIOUS CULTURE SYSTEMS UNDER 100-PERCENT PORCINE AND HUMAN PLASMA CONDITIONS

To select an immobilization method suitable for bioartificial liver (B AL) modules utilizing porcine hepatocyte spheroids, functional activit ies were compared in various systems in 100% porcine and human plasma together with a synthesized medium. The spheroids, continuously suspen ded in rotating dishes or entrapped in collagen (CN) gel, expressed ap proximately two times higher ammonium detoxification abilities over co nventional monolayers during 8 days of direct contact with 100% human or porcine plasma with a standardized inoculum cell number. No signifi cant deterioration was observed in the abilities as compared with that in a synthesized medium. Although the cell number gradually decreased in rotational culture, the abilities per cells remaining on Day 10 we re two times higher than in the CN-gel entrapped spheroids in all the media examined, presumably due to the diffusion limitation by the gel. Thus, in utilizing porcine hepatocyte spheroids in BAL modules, immob ilization allowing direct contact of spheroids with perfused patient p lasma was concluded to be possible and suitable.