[High-level androgen enhances the differentiation of hESCs into male primordial germ cells]

To observe the effects of different concentrations of testosterone on the differentiation of human embryonic stem cells (hESCs) into early male germ cells and investigate the potential impact of high-level androgen exposure in early pregnancy in women with polycystic ovary syndrome (PCOS) on the fertility and primordial germ cell reserve of the male offspring in adulthood.

We used 2 μmol/L retinoic acid to induce the differentiation of hESCs (46, XY) into male germ cells in vitro and meanwhile treated them with testosterone (T) at 0 mol/L, 3×10－7 mol/L, 5×10－7 mol/L, 15×10－7 mol/L, 45×10－7 mol/L, and 135×10－7 mol/L, respectively. We collected the cell samples at 0, 4, 7 and 14 days to determine the expressions of the specific genes and compare the differentiation process and efficiency of the male germ cells in different stages.

There was no difference in the morphology of the hESCs treated with different concentrations of testosterone in the same differentiation stage. The expression of the marker gene DAZL in the primordial germ cells peaked on the 4th day of differentiation, significantly higher in the 15×10－7, 45×10－7 and 135×10－7 mol/L groups than in the 3×10－7 mol/L group (P < 0.05), and that of the specific gene SCP3 in the early-meiosis germ cells began to increase on the same day, more significantly in the 45×10－7mol/L than in the 3×10－7 mol/L and 5×10－7 mol/L groups (P < 0.01), and peaked on the 7th day, dramatically higher in the 15×10－7, 45×10－7 and 135×10－7 mol/L groups than in the 3×10－7 mol/L group (P < 0.01). Immunofluorescence staining and flow cytometry showed a T concentration-dependent increase in the expression of DAZL at 4 days and those of SCP3 and VASA at 7 days. Moreover, the expression of the androgen receptor (AR) in the hESCs began to rise on the 4th day and kept going up till the 14th day, higher in the high-concentration than in the low-concentration T groups in the same stage of differentiation, though with no statistically significant difference (P > 0.05).

Exposure to high-level androgen during the differentiation of hESCs into early male germ cells can induce earlier expression of AR and earlier differentiation of hESCs into early male germ cells, which may result in insufficient reserve of male primary germ cells in the male offspring of PCOS women and affect their fertility after adulthood. hESCs can be used as an in vitro model to study the effects of intrauterine hyperandrogen on the reproductive development of male offspring in PCOS patients, which is also contributive to researches on the etiology of male infertility.