title: Misleading and reliable markers to differentiate between primate testis-derived multipotent stromal cells and spermatogonia in culture.
abstract: BACKGROUND
  Several studies have reported the generation of spermatogonia-derived pluripotent stem cells from human testes. The initial aim of the present study was the derivation of equivalent stem cells from an established and experimentally accessible non-human primate model, the common marmoset monkey (Callithrix jacchus). However, an essential prerequisite in the absence of transgenic reporters in primates and man is the availability of validated endogenous markers for the identification of specific cell types in vitro.
  
  
  RESULTS
  We cultured marmoset testicular cells in a similar way to that described for human testis-derived pluripotent cells and set out to characterize these cultures under different conditions and in differentiation assays applying established marker panels. Importantly, the cells emerged as testicular multipotent stromal cells (TMSCs) instead of (pluripotent) germ cell-derived cells. TMSCs expressed many markers such as GFR-α, GPR125, THY-1 (CD90), ITGA6, SSEA4 and TRA-1-81, which were considered as spermatogonia specific and were previously used for the enrichment or characterization of spermatogonia. Proliferation of TMSCs was highly dependent on basic fibroblast growth factor, a growth factor routinely present in germ cell culture media. As reliable markers for the distinction between spermatogonia and TMSCs, we established VASA, in combination with the spermatogonia-expressed factors, MAGEA4, PLZF and SALL4.
  
  
  CONCLUSIONS
  Marmoset monkey TMSCs and spermatogonia exhibit an overlap of markers, which may cause erroneous interpretations of experiments with testis-derived stem cells in vitro. We provide a marker panel for the unequivocal identification of spermatogonia providing a better basis for future studies on primate, including human, testis-derived stem cells.
authors.affiliation: German Primate Center, Leibniz Institute for Primate Research, Kellnerweg 4, Göttingen, Germany.
authors.forename: K
authors.initials: K
authors.lastname: Eildermann
authors.forename: J
authors.initials: J
authors.lastname: Gromoll
authors.forename: R
authors.initials: R
authors.lastname: Behr
mesh_terms: D000818:Animals; D015415:Biomarkers / Q000032:analysis*; D002144:Callithrix; D002478:Cells, Cultured; D008297:Male; D039902:Multipotent Stem Cells / Q000737:chemistry*; D039904:Pluripotent Stem Cells / Q000737:chemistry; D013093:Spermatogonia / Q000737:chemistry*; D017154:Stromal Cells / Q000737:chemistry; D013737:Testis / Q000166:cytology*
chemical_list: D015415:Biomarkers