Induction of E-cadherin(+) human amniotic fluid cell differentiation into oocyte-like cells via culture in medium supplemented with follicular fluid

Pluripotent human amniotic fluid cells (HuAFCs) can differentiate into various types of somatic cell in vitro. However, their differentiation into oocyte-like cells has never been described to the best of our knowledge. In the present study, differentiation of E-cadherin(+) and E-cadherin(−) HuAFC sub-populations into oocyte-like cells was induced via culture in medium containing bovine follicular fluid and β-mercaptoethanol. The E-cadherin(+) HuAFCs expressed DAZL highly. Post-induction, cells with an oocyte-like phenotype were found among the E-cadherin(+) HuAFCs, expressing markers specific to germ cells and oocytes (VASA, ZP3 and GDF9) and meiosis (DMC1 and SCP3). When specific small interfering RNA (siRNA) was used to suppress E-cadherin in the E-cadherin(+) HuAFCs, the levels of DAZL expression were reduced. Post-induction, the morphology of the siRNA-E-cadherin HuAFCs was poorer and the expression levels of germ cell-specific markers were lower compared with those of the siRNA-mock HuAFCs. Therefore, E-cadherin(+) HuAFCs could be more easily induced to differentiate into oocyte-like cells by bovine follicular fluid and β-mercaptoethanol. In addition, the E-cadherin(+) HuAFCs exhibited potential characteristics of DAZL protein expression, and thus it was conjectured that bovine follicular fluid acts on DAZL protein and promotes E-cadherin(+) HuAFC differentiation into oocyte-like cells.