EMBRYONIC STEM-CELL LINES DERIVED FROM HUMAN BLASTOCYSTS

Human blastocyst-derived, pluripotent cell lines are described that ha ve normal karyotypes, express high levels of telomerase activity, and express cell surface markers that characterize primate embryonic stem cells but do not characterize other early lineages. After undifferenti ated proliferation in vitro for 4 to 5 months, these cells still maint ained the developmental potential to form trophoblast and derivatives of all three embryonic germ layers, including gut epithelium (endoderm ); cartilage, bone, smooth muscle, and striated muscle (mesoderm); and neural epithelium, embryonic ganglia, and stratified squamous epithel ium (ectoderm). These cell lines should be useful in human development al biology, drug discovery, and transplantation medicine.