title: Primordial germ cell specification from embryonic stem cells.
abstract: BACKGROUND
  Primordial germ cell (PGC) specification is the first crucial step in germ line development. However, owing to significant challenges regarding the in vivo system, such as the complex cellular environment and potential problems with embryo manipulation, it is desirable to generate embryonic stem (ES) cells that are capable of overcoming these aforementioned limitations in order to provide a potential in vitro model to recapitulate the developmental processes in vivo.
  
  
  RESULTS
  Here, we studied the detailed process of PGC specification from stella-GFP ES cells. We first observed the heterogeneous expression of stella in ES cells. However, neither Stella-positive ES cells nor Stella-negative ES cells shared a similar gene expression pattern with either PGCs or PGC precursors. Second, we derived PGCs from ES cells using two differentiation methods, namely the attachment culture technique and the embryoid body (EB) method. Compared with PGCs derived via the attachment culture technique, PGCs derived via the EB method that had undergone the sequential erasure of Peg3 followed by Igf2r resulted in a cell line in which the expression dynamics of T, Fgf8 and Sox17, in addition to the expression of the epiblast markers, were more similar to the in vivo expression, thus demonstrating that the process of PGC derivation was more faithfully recapitulated using the EB method. Furthermore, we developed an in vitro model of PGC specification in a completely chemically defined medium (CDM) that indicated that BMP4 and Wnt3a promoted PGC derivation, whereas BMP8b and activinA had no observable effect on PGC derivation.
  
  
  CONCLUSIONS
  The in vitro model we have established can recapitulate the developmental processes in vivo and provides new insights into the mechanism of PGC specification.
authors.affiliation: Laboratory of Chemical Genomics, School of Chemical Biology and Biothechnology, Shenzhen Graduate School of Peking University, Shenzhen, China.
authors.forename: Wei
authors.initials: W
authors.lastname: Wei
authors.forename: Tingting
authors.initials: T
authors.lastname: Qing
authors.forename: Xin
authors.initials: X
authors.lastname: Ye
authors.forename: Haisong
authors.initials: H
authors.lastname: Liu
authors.forename: Donghui
authors.initials: D
authors.lastname: Zhang
authors.forename: Weifeng
authors.initials: W
authors.lastname: Yang
authors.forename: Hongkui
authors.initials: H
authors.lastname: Deng
mesh_terms: D000818:Animals; D055415:Bone Morphogenetic Protein 4 / Q000235:genetics / Q000378:metabolism; D018929:Cell Culture Techniques; D002454:Cell Differentiation / Q000235:genetics / Q000502:physiology*; D002478:Cells, Cultured; D002868:Chromosomal Proteins, Non-Histone; D053595:Embryonic Stem Cells / Q000378:metabolism / Q000502:physiology*; D018507:Gene Expression Regulation, Developmental; D005854:Germ Cells / Q000378:metabolism / Q000502:physiology*; D049452:Green Fluorescent Proteins / Q000235:genetics / Q000378:metabolism; D051379:Mice; D008954:Models, Biological; D012097:Repressor Proteins / Q000235:genetics / Q000378:metabolism; D019076:Transgenes
chemical_list: C525810:Bmp4 protein, mouse; D055415:Bone Morphogenetic Protein 4; D002868:Chromosomal Proteins, Non-Histone; C462180:Dppa3 protein, mouse; D012097:Repressor Proteins; D049452:Green Fluorescent Proteins