Supplementation of IVM culture media with GDF-9 can potentially enhance oocyte quality, fertilization and embryo development in ICSI procedure

In vitro maturation (IVM) of human oocytes is an important factor in assisted reproductive technology (ART) laboratories. The present study was aimed to investigate the effect of growth differentiation factor 9 (GDF-9) supplemented into IVM medium, and co-culture of cumulus cells (CCs) on IVM outcome. 385 immature oocytes in the germinal vesicle (GV) stage were divided into four groups in terms of IVM culture condition; 1) GV oocytes cultured in standard IVM medium (control), 2) GV oocytes co- cultured with CCs, 3) GV oocytes treated with GDF-9, and 4) GV oocytes co- cultured with CCs and treated with GDF-9, simultaneously. The presence of meiotic spindle (MS) and zona pellucida (ZP) birefringence were assessed in IVM oocytes, followed by intracytoplasmic sperm injection (ICSI). Finally, fertilization rate and embryo development in day 2 embryos were evaluated. The maturation rates of GV oocytes were similar in whole groups following 24-48 h of incubation. A significantly higher rate of oocytes matured in the medium treated with CCs reached into 2 pronuclear (2PN) stage compared to those matured in the standard medium, respectively (76.5% vs. 51.6%, P= 0.01). The percentage of oocytes with visible MS was higher in all treated groups, but this alteration was significant between oocytes matured in medium supplemented with GDF-9 and control group (45% vs. 26.6% respectively, P= 0.05). Co-culturing of GV oocytes with CCs and/or supplementation of the IVM medium with GDF-9 can potentially improve fertilization rate and embryo development. Also, MS assessment provides an early predictor of embryo development.