title: Activin/Nodal inhibition alone accelerates highly efficient neural conversion from human embryonic stem cells and imposes a caudal positional identity.
abstract: BACKGROUND
  Neural conversion from human embryonic stem cells (hESCs) has been demonstrated in a variety of systems including chemically defined suspension culture, not requiring extrinsic signals, as well as in an adherent culture method that involves dual SMAD inhibition using Noggin and SB431542 (an inhibitor of activin/nodal signaling). Previous studies have also determined a role for activin/nodal signaling in development of the neural plate and anterior fate specification. We therefore sought to investigate the independent influence of SB431542 both on neural commitment of hESCs and positional identity of derived neural progenitors in chemically defined substrate-free conditions.
  
  
  RESULTS
  We show that in non-adherent culture conditions, treatment with SB431542 alone for 8 days is sufficient for highly efficient and accelerated neural conversion from hESCs with negligible mesendodermal, epidermal or trophectodermal contamination. In addition the resulting neural progenitor population has a predominantly caudal identity compared to the more anterior positional fate of non-SB431542 treated cultures. Finally we demonstrate that resulting neurons are electro-physiologically competent.
  
  
  CONCLUSIONS
  This study provides a platform for the efficient generation of caudal neural progenitors under defined conditions for experimental study.
authors.affiliation: Anne McLaren Laboratory for Regenerative Medicine & Cambridge Centre for Brain Repair, Department of Clinical Neurosciences, University of Cambridge, Cambridge, United Kingdom.
authors.forename: Rickie
authors.initials: R
authors.lastname: Patani
authors.forename: Alastair
authors.initials: A
authors.lastname: Compston
authors.forename: Clare A
authors.initials: CA
authors.lastname: Puddifoot
authors.forename: David J A
authors.initials: DJ
authors.lastname: Wyllie
authors.forename: Giles E
authors.initials: GE
authors.lastname: Hardingham
authors.forename: Nicholas D
authors.initials: ND
authors.lastname: Allen
authors.forename: Siddharthan
authors.initials: S
authors.lastname: Chandran
mesh_terms: D028341:Activins / Q000378:metabolism*; D001549:Benzamides / Q000494:pharmacology; D019521:Body Patterning; D002448:Cell Adhesion; D002454:Cell Differentiation; D002460:Cell Line; D004149:Dioxoles / Q000494:pharmacology; D053595:Embryonic Stem Cells / Q000166:cytology*; D006801:Humans; D007150:Immunohistochemistry; D009474:Neurons / Q000378:metabolism*; D055457:Nodal Protein / Q000378:metabolism*; D018408:Patch-Clamp Techniques; D020133:Reverse Transcriptase Polymerase Chain Reaction; D015398:Signal Transduction; D013234:Stem Cells / Q000166:cytology
chemical_list: C459179:4-(5-benzo(1,3)dioxol-5-yl-4-pyridin-2-yl-1H-imidazol-2-yl)benzamide; D001549:Benzamides; D004149:Dioxoles; D055457:Nodal Protein; D028341:Activins