Induction of dedifferentiated male mouse adipose stromal vascular fraction cells to primordial germ cell‐like cells

The adipose stromal vascular fraction (SVF) contains abundant mesenchymal stem cell populations that have a limited ability to self-renew and differentiate. Male mouse adipose SVF cells were dedifferentiated by reprogramming factors (c-Myc, Oct4, Sox2, and Klf4) to form embryonic stem cell-like cells (ESCLCs), which upgraded their limited differentiation potential. The ESCLCs were induced to differentiate toward epiblast-like cells (EpiLCs) and primordial germ cell-like cells (PGCLCs) by culturing in media supplied with activin A and BMP-4, respectively. The derived ESCLCs possess embryonic stem cell features and can automatically form embryonic bodies. After culture in EpiLC induction medium for 2-3 days, ESCLCs formed flattened epithelial structures that were different from their original water drop-like colonies, and the expression of pluripotency-related genes decreased. When the cells that had been cultured in EpiLC induction medium for 2 days were isolated and cultured in PGCLC induction medium for 4-6 days, they formed typical water drop-like colonies again. Moreover, expression of the pluripotency-related genes and the primordial germ cell (PGC) specification-related genes increased. During progression from ESCLCs toward EpiLCs and PGCLCs, the levels of histone methylases H3K9me2 and H3K27me3 kept changing, which resembled those seen in PGC specification. The derived PGCLCs expressed SSEA-1, Blimp-1, and Stella. Furthermore, methylation of Igf2r and Snrpn was retained, but H19 and Kcnq1ot1 methylation levels were slightly reduced compared to non-PGCLCs, suggesting that the derived PGCLCs may have initiated the process of imprint erasure.