FGF2 Signaling Plays an Important Role in Maintaining Pluripotent State of Pig Embryonic Germ Cells.

Germ cells are alternative sources for deriving pluripotent stem cells. Because embryonic germ cells (EGCs) possess physiological and developmental features similar to those of embryonic stem cells, pig EGCs are considered a potential tool for generating transgenic animals for agricultural usage. Therefore, in this study, we attempted to establish and characterize pig EGCs from fetal gonads. EGC lines were derived from the genital ridges of porcine fetuses in media containing leukemia inhibitory factor (LIF), fibroblast growth factor 2 (FGF2), and stem cell factor. After establishment, these cells were cultured and stabilized in LIF- or FGF2-containing media. The cell lines were maintained under both conditions over an extended time period and spontaneously differentiated into the three germ layers in vitro. Interestingly, expression of pluripotency markers showed different patterns between cell lines cultured in LIF or FGF2. SSEA4 was only expressed in FGF2-treated pig EGCs (FGF2-pEGCs), not LIF-treated pig EGCs (LIF-pEGCs). Pluripotency genes were upregulated in FGF2-pEGCs, and germline markers were highly expressed, indicating that FGF2 supplements are more efficient in supporting the pluripotency of pEGCs. In conclusion, we verified that FGF2 signaling plays an important role in reprogramming and maintaining pEGCs from fetal gonads.