[Establishment, maintenance and differentiation induction of embryonic stem cells].

Embryonic stem(ES) cells are the cell lines derived from the inner cell mass of early preimplantation embryos at blastocyst stage. Mouse ES cells are pluripotent since the cells can be differentiated into all lineages of the cells once re-introduced into blastocysts. Human ES cells have been established from the inner cell mass of blastocysts which are developed from surplus embryos obtained by in vitro fertilization. ES cells are considered valuable resource of regeneration medicine because of their vigorous proliferative activity and broad differentiation capacity. Establishment, maintenance and in vitro differentiation of the cells are key points for the utilization of ES cells in regeneration medicine.