Expression of pluripotent stem cell markers in the human fetal ovary

BACKGROUND: Human primordial germ cells (PGCs) can give rise to pluripotent stem cells such as embryonal carcinoma cells (ECCs) and embryonic germ cells (EGCs). METHODS: In order to determine whether PGCs express markers associated with pluripotency in EGCs and ECCs, the following study cross examines the expression patterns of multiple pluripotent markers in the human fetal ovary, 5.5-15 weeks post-fertilizaton (pF) and relates this expression with the ability to derive pluripotent EGCs in vitro. RESULTS: Specific subpopulations were identified which included OCT4⁺/Nanog⁺/cKIT ⁺/VASA⁺ PGCs and oogonia. Interestingly, these cells also expressed SSEA1 and alkaline phosphatase (AP) and SSEA4 expression occurred throughout the entire gonad. Isolation of SSEA1⁺ cells from the gonad resulted in AP⁺ EGC colony formation. The number of OCT4⁺ or Nanog⁺ expressing cells peaked by week 8 and then diminished after week 9 pF, as oogonia enter meiosis. In addition, the efficiency of EGC derivation was associated with the number of OCT4⁺ cells. TRA-1-60 and TRA-1-81 were only detected in the lining of the mesonephric ducts and occasionally in the gonad. CONCLUSIONS: These results demonstrate that PGCs, a unipotent cell, express most, but not all, of the markers associated with pluripotent cells in the human fetal ovary.