We studied neural induction and generation of neuroectoderm in the colonies of human parthenogenetic SC cultured in the presence of 5 and 19±2% oxygen. We found that neuroectoderm was more actively generated at high oxygen content. At the same time, the transcription of stem cell pluripotency genes was not completely suppressed during neural induction at low oxygen content, while the expression of endoderm and mesodermal marker genes attested to the absence of specifi c differentiation. These fi ndings demonstrate more effi cient neuroectoderm generation induced in the colonies of pluripotent stem cells under conditions of normoxia.
http://link.springer.com/article/10.1007/s10517-012-1892-4#

We studied the effect of recombinant human activin A on induced neuroectoderm formation in colonies of human parthenogenetic SC in the absence of feeder cells. It was found that pretreatment of human parthenogenetic SC with activin A suppressed subsequent neural induction. Activin A in a concentration of 10 ng/ml significantly decreased transcriptional activity of genes required for neuroectoderm formation. At the same time, activin A in a concentration of 20 ng/ml increased the expression of pluripotency genes and completely inhibited the formation of structures in vitro reproducing the neural tube of the developing embryo. These findings attest to prolonged effect of activin A as an inhibitor of neuroectodermal differentiation.
Semechkin R.A., Abramihina T.V., Isaev D.A. Activin A Suppresses Induced Formation of Neuroectoderm in Colonies of Parthenogenetic Stem Cells In Vitro. Bulletin of Experimental Biology and Medicine. Volume 151, Number 4, 502-505, DOI: 10.1007/s10517-011-1367-z Translated from Kletochnye Tekhnologii v Biologii i Meditsine, No. 2, pp. 67–70, April, 2011