title: Generation of germ cells in vitro in the era of induced pluripotent stem cells.
abstract: Induced pluripotent stem cells (iPSCs) are stem cells that can be artificially generated via "cellular reprogramming" using gene transduction in somatic cells. iPSCs have enormous potential in stem-cell biology as they can give rise to numerous cell lineages, including the three germ layers. An evaluation of germ-line competency by blastocyst injection or tetraploid complementation, however, is critical for determining the developmental potential of mouse iPSCs towards germ cells. Recent studies have demonstrated that primordial germ cells obtained by the in vitro differentiation of iPSCs produce functional gametes as well as healthy offspring. These findings illustrate not only that iPSCs are developmentally similar to embryonic stem cells (ESCs), but also that somatic cells from adult tissues can produce gametes in vitro, that is, if they are reprogrammed into iPSCs. In this review, we discuss past and recent advances in the in vitro differentiation of germ cells using pluripotent stem cells, with an emphasis on ESCs and iPSCs. While this field of research is still at a stage of infancy, it holds great promises for investigating the mechanisms of germ-cell development, especially in humans, and for advancing reproductive and developmental engineering technologies in the future.
authors.affiliation: Department of Physiology, School of Medicine, Keio University, Shinjuku-ku, Tokyo, Japan.
authors.forename: Masanori
authors.initials: M
authors.lastname: Imamura
authors.forename: Orie
authors.initials: O
authors.lastname: Hikabe
authors.forename: Zachary Yu-Ching
authors.initials: ZY
authors.lastname: Lin
authors.forename: Hideyuki
authors.initials: H
authors.lastname: Okano
mesh_terms: D000818:Animals; D057005:Bioengineering / Q000379:methods* / Q000639:trends; D002454:Cell Differentiation / Q000502:physiology*; D053595:Embryonic Stem Cells / Q000166:cytology*; D005854:Germ Cells / Q000166:cytology / Q000254:growth & development*; D006801:Humans; D057026:Induced Pluripotent Stem Cells / Q000166:cytology*; D051379:Mice
keywords: ES cells; Germ cells; iPS cells; in vitro differentiation