Establishment and characterization of embryonic stem cell and embryonic germ cell in human and mouse

초록

Pluripotent stem cells (PSCs) are unique cell populations with the ability to maintain in culture in an undifferentiated state, proliferate indefinitely and, upon differentiation, generate a wide variety of cell types. These cells are divided into two kinds according to the origin. Embryonic stem (ES) cells are derived from the inner cell mass (ICM) of blastocysts and embryonic germ (EG) cells are derived from primordial germ cells of the developing gonadal ridge Human and nonhuman primate ES cells share a similar morphology that is distinct from human EG and mouse. Human ES cells from relatively flat, compact colonies that easily dissociate into single cells, whereas human EG cells form tight, more spherical colonies that are refractory to standard dissociation methods. The population-doubling time of mouse ES cells is 12 hours, whereas the population-doubling time of human ES cells is about 36 hours. Like undifferentiated primate ES cells and human EC cells, human ES cells express stage-specific embryonic antigens 3 and 4 (SSEA-3 and SSEA-4), and alkaline phosphatase (AP). Undifferentiated mouse ES cells and human EG cells do not express SSEA-3, but do express the lactoseries glycolipid SSEA-1, which is not expressed in human ES cells, rhesus ES cells, or human EC cells. Human ES line has a normal 46, XY karyotype. Human ES cells and EG cells differ from mouse ES cells in their in vitro culture requirements for undifferentiated growth. Mouse ES cells require leukemia inhibitory factor (LIF) for undifferentiated proliferation. In contrast, LIF alone is not sufficient to prevent differentiation of human ES cells in vitro. Instead, continued undifferentiated propagation of human ES cells currently requires feeder layers and basic fibroblast growth factor (bFGF). The pluripotent cells including ES and EG maintained the potential to form derivatives of all three embryonic germ layers. ES and EG cells produced teratomas after injection into nude mouse. Each injected mouse formed a teratomas included gut, epithelium (endoderm): cartilage, bone, smooth muscle, and striated muscle (mesoderm), and neural epithelium, embryonic ganglia and stratified squamous epithlium (ectoderm). The differentiation of pluripotent stem cell is spontaneous and unregulated in vitro. We try to make an initial and broad scan for the effects of various growth factors and to assess their ability to regulate ES cell differentiation. The ability to induce specific differentiation was initially evident as morphological changes in the differentiated cell culture. To assess their differentiation by gene expression, we analyzed the transcription of 9 tissue-specific markers from all three germ layers and sublayers. Clustering the growth factors based on their effects on differentiation reveals three groups. The first group (bFGF) induced ectodermal and endodermal cells. The second group (TGF-b1, EGF) inhibited ectodermal cells differentiation but allow or induce differentiation of endodermal or mesodermal cells. The third group (NGF, OSM, and IGF-1) induced differentiation into all three embryonic lineages. None of the six growth factors directs neither complete nor singular differentiation of the cells. ES and EG cells will be particularly valuable for the study of the development, function of tissues, in intro guided-differentiation, early development of embryo and transplantation medicine.