The concentration of human follicular fluid stromal cell-derived factor-1 is correlated with luteinization in follicles

Stromal cell-derived factor-1 (SDF-1/CXCL12) and vascular endothelial growth factor (VEGF) are angiogenic factors that have possible roles in ovarian function. The objectives of this study were to investigate the association between the individual concentrations of SDF-1 and VEGF and sex steroid hormones in human preovulatory follicles and to verify the SDF-1 expression in ovarian follicles. Follicular fluid (FF) and luteinizing granulosa cells (LGCs) were collected from follicles at the time of oocyte retrieval. The concentrations of SDF-1, VEGF, estradiol (E₂) and progesterone (P₄) were determined by biochemical assay. The expression levels of SDF-1 mRNA and protein were analyzed by RT-PCR and immunohistochemical analysis, respectively. A total of 177 follicles were analyzed. The FF concentrations of SDF-1 and VEGF positively correlated with P₄ concentrations (r = 0.457 and p < 0.01, r = 0.698 and p < 0.01, respectively), but did not correlate with E₂ concentrations in FF. Furthermore, we confirmed that SDF-1 mRNA was expressed in LGCs and SDF-1 protein is present in the granulosa cells of the human ovary. Our findings suggest that SDF-1, as well as VEGF, may play important modulatory roles in early luteinization of human preovulatory follicles.