The first method to cause a culture of human and other primate stem cells todirectly and uniformly differentiate into a committed cell lineage isdisclosed. Treatment of primate stem cells with a single protein trophoblastinduction factor causes the cells to transform into human trophoblast cells,the precursor cells of the placenta. Several protein factors including bonemorphogenic protein 4 (BMP4), BMP2, BMP7, and growth and differentiationfactor 5 can serve as trophoblast-inducting factors.
