Stem cells are defined by two important characteristics: the ability to proliferate by a process of self-renewal and the potential to form at least one specialized cell type. Transient population of pluripotent or multipotent stem cells first appear during the development at the first days post coitum. The cells of the inner cell mass (ICM) of the blastocyst, of which embryonic stem cells (ES) are the in vitro counterpart, can give rise to any differentiated cell type in the three primary germ layers of the embryo (endoderm, mesoderm and ectoderm).~(1-3) These cells gradually mature into committed, organ- and tissue-specific stem cells or adult stem cells, such as neural stem cells, mesenchymal stem cells, hematopoietic stem cells, etc. Over the past years, studies have focused on two aspects: molecular level and application, and some new methods and technology have been used. Stem cells are defined by two important characteristics: the ability to proliferate by a process of self-renewal and the potential to form at least one specialized cell type. Transient population of pluripotent or multipotent stem cells first appear during the development at the first days post The cells of the inner cell mass (ICM) of the blastocyst, of which embryonic stem cells (ES) are the in vitro counterpart, can give rise to any differentiated cell type in the three primary germ layers of the embryo (endoderm, These cells gradually mature into committed, organ- and tissue-specific stem cells or adult stem cells, such as neural stem cells, mesenchymal stem cells, hematopoietic stem cells, etc. Over the past years, studies have focused on two aspects: molecular level and application, and some new methods and technology have been used.