摘要：It is well known that it would be important to cultivate human hepatocytes of about 1010 cells at a high cell density, about 1×107 cells/cm3, in the bioreactor for the development of bioartificial liver. However, since primary human hepatocytes lack an ability to proliferate in vitro , it is essential to establish a culture method for the proliferation of normal human hepatic stem cells as a cell source. In this study, it was found that human hepatoblasts, a kind of hepatic stem cells, were induced from human fetal hepatocytes while keeping the ability of proliferation by the treatment of 1m M sodium butyrate (SB) for 12 d of culture. The transformation of hepatoblasts was evaluated by abnormal prothrombin (PIVKA-II) assay, which is a clinical marker for hepatocellular carcinoma. The PIVKA-II production rate of the cells was suppressed to the normal level under 1 m M SB. The cells including hepatoblasts under 1 m M SB attached to the porous hydroxyapatite carriers and proliferated to a high cell density of about 1×107 cells/cm3 in the carriers. The liver-specific function, cytochrome P450 3A4 activity (4.2 pmol/mg protein/min) of the cells in the carriers under 1 m M SB was comparable to that of primary human hepatocytes. Ammonia metabolizing activity (0.21 μmol/106 cells/h) of the cells was also comparable to that of porcine hepatocytes used in the bioartificial liver. The PIVKA-II production rate of the cells in the carrier was suppressed to the normal level. These results suggested that induction of human hepatoblasts from fetal hepatocytes by the treatment of 1m M SB and proliferation of the cells at a high cell density using hydroxyapatite carriers should be one of the more promising culture methods for bioartificial liver developments.
