Embryonic stem cell-like cells established by culture of adult ovarian cells in mice

Objective To suggest an alternative strategy for deriving histocompatible stems cells without undertaking genetic manipulation. Design Prospective approach using an animal model. Setting Stem cell and bioevaluation laboratory, Seoul National University. Animal(s) F1 (C57BL6 X DBA2) and outbred (ICR) mice. Intervention(s) Ovarian stroma cells of less than 40 μm in diameter were subcultured with fibroblast monolayer, and colony-forming cells were characterized. Main Outcome Measure(s) Stemness, genotype, and imprinted gene methylation. Result(s) Two-lines of colony-forming cells were established, which expressed markers specific for embryonic stem cells (ESC) and formed embryoid bodies and teratomas. Complete matching of microsatellite markers with the cell donor strain confirmed their establishment from ovarian tissue, and identification of both homozygotic and heterozygotic chromosomes raised the possibility of their derivation from parthenogenetic oocytes. However, the use of cells smaller than mature oocytes for primary culture, the difference in imprinted gene methylation compared with parthenogenetic ESCs, and failure to establish the ESC-like cells by primary follicle culture collectively suggested the irrelevancy to gametes. Conclusion(s) Coculture of adult ovarian cells with somatic fibroblasts can yield colony-forming cells having ESC-like activity, which may provide an alternative for establishing autologous stem cells from adults that can be obtained without genetic manipulation.