Effects of growth factors on the differentiation of mouse embryonic stem cells

초록

Embryonic stem (ES) cells are pluripotent, derived from the inner cell mass of blastocyst in mammals. ES cells can be maintained in vitro culture in an undifferentiated and, upon differentiation, generate a variety of cell types. Here, we suggest the possibility of guided differentiation of ES cells by some growth factors. We examined the potential effects of five growth factors [basic fibroblast growth factor (bFGF, 10ng/ml), transforming growth factor-b1 (TGF-b1, 2ng/ml), epidermal growth factor (EGF, 100ng/ml), oncostatin M (OSM, 100ng/ml), insulin-like growth factor-I (IGF-I, 100ng/ml) to induce the differentiation of ES cells in vitro. We observed that expression of growth factor receptors, and compared the morphological changes in ES cells that have initiated differentiation by treatment of five growth factors. We assayed the differentiation of the ES cells by expression of specific molecular markers. Trophoblast marker (hand1), ectodermal markers (fgf5, keratin), mesodermal markers (enolase, a-globin), endodermal markers (gata-4, a-fetoprotein). EGF receptor gene expression was increased by TGF-b1 and OsM. Membrane bounded LIF receptor gene expression was increased by TGF-b1, EGF, and IGF-I. Also, soluble LIF receptor gene expression was increased by IGF-I and bFGF. Each growth factors has a unique effect that may result from direct differentiation and we can divide the overall effects of the factos into 4 categories: All growth factors except bFGF induce trophoblast differentiation; TGF-b1 that mainly induce mesodermal and endodermal cell markers; EGF and bFGF mainly activate endodermal cell markers; IGF1 and OSM that allow differentiation into the three embryonic germ layers. From above results, growth factors could play a key role on the differentiation of stem cells, whereas one growth factor do not induce one cell type and combinations of growth factors may be involved in complicate ES cells differentiation.