Selective elimination of tumorigenic hepatic stem cells using hybrid liposomes

To avoid the risk of tumorigenesis after cell transplantation, tumorigenic stem cells should be selectively eliminated from induced pluripotent cells, embryonic stem cells, and somatic stem cells. We previously reported the presence of tumorigenic stem cells in human fetal hepatocyte-induced hepatoblasts after sodium butyrate (SB) treatment. In this study, we aimed to investigate the selective elimination of tumorigenic stem cells in human hepatoblasts using hybrid liposomes (HLs) prepared by sonicating a mixture of 90 mol% l-α-dimyristoylphosphatidylcholine and 10 mol% polyoxyethylene (n) dodecyl ether (C₁₂ (EO)_n, n = 23) in a buffer solution. Flow cytometric analysis revealed that the number of hepatoblasts increased by around 12-18 times in SB-treated cells compared to non-treated cells. In the colony formation assay, colonies of tumorigenic stem cells were observed in a soft agar plate after SB treatment. HL treatment for 48 h resulted in a remarkable decrease in the number of colonies. HLs also induced apoptosis of tumorigenic stem cells by activating caspase-3. Flow cytometry showed a significant accumulation of HLs, including fluorescent lipids, in tumorigenic hepatic stem cells. The reappearance of tumorigenic stem cells was suppressed even in subsequent subcultures of HL-treated cells. High CYP3A4 activity was observed in a three-dimensional in vitro assay. These results suggest that HL treatment could specifically eliminate tumorigenic hepatic stem cells. Incubation with HLs can be an effective culture method to maintain the quality of stem cells and reduce the risk of tumorigenesis after cell transplantation.