Generation of trophoblast cells from embryonic stem cells using a TGF-beta inhibitor

This protocol describes a method to generate trophoblast-like cells by treatment with SB431542, an activin/nodal inhibitor. Alternatively, follistatin which directly inhibits activin, can be used instead of SB431542. The differentiated cells express trophoblast-specific markers, and secrete hCG, estradiol and progesterone. Note: the above hormones are secreted in-vivo by multinucleated syncytiotrophoblast cells.