title: Totipotent embryonic stem cells arise in ground-state culture conditions.
abstract: Embryonic stem cells (ESCs) are derived from mammalian embryos during the transition from totipotency, when individual blastomeres can make all lineages, to pluripotency, when they are competent to make only embryonic lineages. ESCs maintained with inhibitors of MEK and GSK3 (2i) are thought to represent an embryonically restricted ground state. However, we observed heterogeneous expression of the extraembryonic endoderm marker Hex in 2i-cultured embryos, suggesting that 2i blocked development prior to epiblast commitment. Similarly, 2i ESC cultures were heterogeneous and contained a Hex-positive fraction primed to differentiate into trophoblast and extraembryonic endoderm. Single Hex-positive ESCs coexpressed epiblast and extraembryonic genes and contributed to all lineages in chimeras. The cytokine LIF, necessary for ESC self-renewal, supported the expansion of this population but did not directly support Nanog-positive epiblast-like ESCs. Thus, 2i and LIF support a totipotent state comparable to early embryonic cells that coexpress embryonic and extraembryonic determinants.
authors.affiliation: MRC Centre for Regenerative Medicine, Institute for Stem Cell Research, School of Biological Sciences, University of Edinburgh, 5 Little France Drive, EH16 4UU Edinburgh, UK.
authors.forename: Sophie M
authors.initials: SM
authors.lastname: Morgani
authors.forename: Maurice A
authors.initials: MA
authors.lastname: Canham
authors.forename: Jennifer
authors.initials: J
authors.lastname: Nichols
authors.forename: Alexei A
authors.initials: AA
authors.lastname: Sharov
authors.forename: Rosa Portero
authors.initials: RP
authors.lastname: Migueles
authors.forename: Minoru S H
authors.initials: MS
authors.lastname: Ko
authors.forename: Joshua M
authors.initials: JM
authors.lastname: Brickman
mesh_terms: D000818:Animals; D002454:Cell Differentiation / Q000502:physiology; D002478:Cells, Cultured; D053595:Embryonic Stem Cells / Q000166:cytology* / Q000378:metabolism; D005260:Female; D006801:Humans; D051379:Mice; D008810:Mice, Inbred C57BL; D008822:Mice, Transgenic; D011555:Pseudopregnancy; D039901:Totipotent Stem Cells / Q000166:cytology* / Q000378:metabolism