A long-term culture system based on a collagen vitrigel membrane chamber that supports liver-specific functions of hepatocytes isolated from mice with humanized livers.

During drug discovery, in vitro models are used to predict the in vivo pharmacokinetic and toxicological properties of drug candidates in humans. However, the conventional method of culturing human hepatocytes as monolayers does not necessarily replicate biologic reactions and does not support liver-specific functions, such as cytochrome P450 (CYP) activities, for prolonged periods. To remedy these problems and thus increase and prolong hepatic functions, we developed a culture system comprising a collagen vitrigel membrane (CVM) chamber and PXB-cells®, fresh hepatocytes isolated from liver-humanized chimeric mice (PXB-mice®).

Increase of β2-integrin on adhesion of THP-1 cells to collagen vitrigel membrane.

When human monocyte-derived leukemia (THP-1) cells, which are floating cells, are stimulated with lipid peroxides, or Streptococcus suis, these cells adhere to a plastic plate or endothelial cells. However, it is unclear whether or not non-stimulated THP-1 cells adhere to collagen vitrigel membrane (CVM). In this study, firstly, we investigated the rate of adhesion of THP-1 cells to CVM.

[Selective elimination of the transformed hepatic stem cells using hybrid liposomes].

To realize regenerative medicine, it is very important to eliminate the transformed stem cells selectively included in iPS cells, ES cells and adult stem cells derived from organs, because the transformed stem cells have a risk of tumorigenesis after the cell transplantation. Ueoka et al., have developed hybrid liposomes (HL) which selectively accumulated to membranes of tumor cells and have high inhibitory effects on the growth of tumor cells along with the induction of apoptosis.

Enhancement of drug efflux activity via MDR1 protein by spheroid culture of human hepatic cancer cells.

Human hepatic cancer cells, HepG2, formed spheroids on a poly-L-glutamic acid-coated dish. Doxorubicin (DOX) efflux activity of the cells in spheroid culture was higher than that in monolayer culture due to the higher expression of MDR1 protein of the cells in spheroids compared with those in monolayer. The amount of MDR1 per cell in spheroids was similar to that of hepatic tumor tissue in vivo.