[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. Therefore, we have investigated the application of HL23 (DMPC/10 mol%C(12)(EO)(23)) to the selective elimination of transformed stem cells using hepatoblast, which we could induce from human fetal hepatocytes by the treatment of 1 mM sodium butyrate for 8 days. During the induction process, the transformed cells appeared and produced abnormal prothrombin (PIVKA-II), which is a clinical marker for hepatoma, and also formed colonies in soft agar plate, which is a criteria for neoplastic cell transformation. On the other hand, by the treatment with 0.33 mM HL23 for 96 h during the induction process, PIVKA-II production rate of the cells and colonies formed in the soft agar plate also remarkably decreased less than those of the normal cells. Furthermore, the population of hepatoblasts in the remaining cells increased about four times. These results suggest that the transformed hepatic stem cells could be selectively eliminated by the treatment of HL23, and HL treatment of the stem cells would be a useful culture method for quality control of the stem cells to reduce a risk of tumorigenesis after the cell transplantation.