An effective enucleation method for murine embryonic stem cells *
Embryonic stem cells (ES cells) are self-renewing and can generate all cell types. In the near future, it is likely that tissues and organs differentiated from human ES cells will be used as materials for transplantation. However, to achieve this goal in regenerative medicine, the immunological rejection of transplanted tissues and organs from the host must be overcome. If the genomic information of ES cells could be replaced within a patient, immunological rejection could be avoided. In the preparation of nuclei-replaced ES cells, it might be possible to replace the nuclei manipulated unfertilized oocytes with ones from a patient's somatic cells using original material, but this method raises bioethical problems. In the study reported here, nuclei were removed from mouse cultured ES cells (E14TG2a) by two enucleation methods, the disk method or the density gradient method. Both methods utilized cytochalasin B to depolymerize actin filament, and resulted in enucleation from cells undercentrifugation. Approximately 23-42% of nuclei were removed from ES cells by the disk method, while 40% were removed by the density gradient method. In the future, these methods will allow us to replace ES nuclei with those of a patient's somatic cells. (Accepted on October 20, 2003)
