Activin/Nodal and FGF pathways cooperate to maintain pluripotency of human embryonic stem cells

Maintenance of pluripotency is crucial to the mammalian embryo's ability to generate the extra-embryonic and embryonic tissues that are needed for intrauterine survival and foetal development. The recent establishment of embryonic stem cells from human blastocysts (hESCs) provides an opportunity to identify the factors supporting pluripotency at early stages of human development. Using this in vitro model, we have recently shown that Nodal can block neuronal differentiation, suggesting that TGFbeta family members are involved in cell fate decisions of hESCs, including preservation of their pluripotency. Here, we report that Activin/Nodal signalling through Smad2/3 activation is necessary to maintain the…