Characterization of ovarian progenitor cells for their potential to generate steroidogenic theca cells in vitro

Abstract

Background: Adult mammalian ovaries contain stem/progenitor cells necessary for folliculogenesis and ovulation-related tissue rupture repair. Theca cells are recruited and developed from progenitors during the folliculogenesis. Theca cell progenitors were not well-defined. The aim of current study is to compare the potential of four ovarian progenitors with defined markers (LY6A, EPCR, LGR5and PDGFRA) to form steroidogenic theca cells in vitro. Methods: Ovarian progenitors were identified by the above four makers reported previously. The location of the cells was determined by immunohistochemistry and immunofluorescence staining of ovarian sections of adult mice. Different progenitor populations were purified by magnetic-activated cell sorting (MACS) and/or fluorescence-activated cell sorting (FACS) techniques from ovarian cell preparation and were tested for their abilities to generate steroidogenic theca cells in vitro. The cells were differentiated with a medium containing LH, ITS and DHH agonist for 12 days. Results: EPCR+ and LGR5+ cells primarily distributed along ovarian surface epitheliums (OSE), while LY6A+ cells distributed in both OSE and parenchyma. However, PDGFRA+ cells were exclusively located in interstitial compartment. When the progenitors were purified by these markers and differentiated in vitro, LY6A+ and PDGFRA+ cells formed steroidogenic cells expressing both CYP11A1 and CYP17A1 and primarily producing androgens, showing characteristics of theca-like cells, while LGR5+ cells generated steroidogenic cells devoid of CYP17A1 expression and androgen production, showing a characteristic of progesterone-producing cells (granulosa- or lutea-like cells). Conclusion: Progenitors from both OSE and parenchyma of adult mice are capable of generating steroidogenic cells with different steroidogenic capacities, showing a possible lineage preference.