Characteristic gene expression induced by polyurethane foam/spheroid culture of hepatoma cell line, Hep G2 as a promising cell source for bioartificial liver

Background/Aims: Polyurethane foam (PUF)/ spheroid-culture can improve liver-specific functions of hepatoma cell line, Hep G2. Therefore, gene expression profile in the PUF/spheroid culture is hypothesized to be different from that in the monolayer culture. The aim of this study is to clarify the characteristic gene expression in PUF/spheroid-cultured Hep G2 cells, as a cell source for bioartificial liver (BAL), using microarray analysis. Methodology: Morphological change and liver specific functions of ammonia removal rate and albumin synthesis rate of Hep G2 were compared between in a monolayer or PUF/spheroid culture. Microarray analysis was performed using cDNA microarrays made in Hitachi Software Engineering Co., Ltd., (Yokohama, Japan), which contains a total of 1,281 cDNA clones. Results: The ammonia removal rate of Hep G2 spheroids increased to 369%, and the albumin synthesis rate of Hep G2 spheroids also increased 311% when compared with monolayer culture. In addition, the ammonia removal capacity of primary human hepatocytes in the PUF/spheroid culture was superior to that in the monolayer culture. The microarray analysis demonstrated that the PUF/spheroid-cultured Hep G2 cells expressed 39 up-regulated (more than 3.0-fold) and 31 down-regulated (less than 0.333-fold) genes. Among the 70 genes differentially expressed in PUF/spheroid cultured Hep G2 cells, subsets of glutathione S-transferase- and angio-tensin-related genes were drastically up-regulated, on the other hand, subsets of assigned for growth factor, glucocorticoid, and stress response, were down-regulated. Conclusions: Hepatoma cell line, Hep G2 cells in the PUF/spheroid culture is a promising hepatocyte source for BAL. Microarray analysis revealed a number of characteristic genes altered by the PUF/spheroid.