Development of a culture process for preventing transformation of normal hepatic stem cells and its application to regenerative medicine

对于再生医学来说，干细胞必须在体外增殖，才能达到细胞治疗所需的细胞数量。如果正常干细胞在增殖过程中转化，这些细胞就不能应用于再生医学，因为有发生肿瘤的风险。事实上，干细胞和转化的肿瘤细胞具有相似的特征和标记。本研究以临床肝细胞肿瘤标志物PIVKA-II(异常凝血酶原)为转化标记物，研究了防止人肝干细胞(肝母细胞)转化的培养新工艺。1、三维培养对肝母细胞转化的影响人肝母细胞在聚L-谷氨酸包被的培养皿上形成三维球体。杂化脂质体对转化的肝母细胞的诱导凋亡作用Ueoka教授等人研制的杂化脂质体可诱导转化的肿瘤细胞凋亡，但不能诱导正常细胞的凋亡。本研究提示，复合脂质体处理肝母细胞可减少PIVKA-II的产生，诱导肝母细胞的凋亡。3、培养载体对肝母细胞转化的影响为了大规模培养人干细胞，有必要对培养载体的材料特性进行研究，以防止细胞转化。在这项研究中，我们考察了几种培养载体。大孔载体更适合人成肝细胞的高密度培养和防止细胞转化。

For regenerative medicine, it is necessary that stem cells will be proliferated in vitro to be attained a required cell number for the cell therapy. If normal stem cells transform in propagation process, these cells can not be applicable to regenerative medicine for the risk of tumor genesis. In fact, the stem cells and transformed tumor cells have similar characteristics and makers. In this research, we studied on development of new culture process for preventing transformation of human hepatic stem cells (hepatoblasts) using PIVKA-II (abnormal prothrombin) as a transformation maker, which is clinical tumor maker of hepatocytes.1, Effect of three dimensional culture on the transformation of hepatoblastsHuman hepatoblasts formed the three dimensional spheroid on the poly-L-glutamic acid coated dish. The PIVKA-II production rate of hepatoblasts was decreased and their transformation was prevented.2, Effect of hybrid liposomes on the induction of apoptosis of transformed hepatoblastsHybrid liposomes developed by Prof. Ueoka et al., are known to induce apoptosis of transformed tumor cells, but not of normal cells. In this study, It was suggested that decrease of PIVKA-II production and apoptosis induction of hepatoblasts by the treatment of hybrid liposomes.3, Effect of culture carriers on the transformation of hepatoblastsFor mass culture of human stem cells, it is necessary to study on material characteristics of culture carriers for preventing transformation of the cells. In this research, we examined several culture carriers. Macro porous carrier was better for cultivating human hepatoblasts at high density and preventing transformation of the cells.