Embryonic stem cell lines from human blastocysts: somatic differentiation in vitro

We describe the derivation of pluripotent embryonic stem (ES) cells from hu man blastocysts. Two diploid ES cell lines have been cultivated in vitro fo r extended periods while maintaining expression of markers characteristic o f pluripotent primate cells. Human ES cells express the transcription facto r Oct-4, essential for development of pluripotential cells in the mouse. Wh en grafted into SCID mice, both lines give rise to teratomas containing der ivatives of all three embryonic germ layers. Both cell lines differentiate in vitro into extraembryonic and somatic cell lineages. Neural progenitor c ells may be isolated from differentiating ES cell cultures and induced to f orm mature neurons. Embryonic stem cells provide a model to study early hum an embryology, an investigational tool for discovery of novel growth factor s and medicines, and a potential source of cells for use in transplantation therapy.