Embryonic Stem Cell Conditioned Medium Supports In Vitro Maturation of Mouse Oocytes

BACKGROUND This study aimed to investigate the maturation and fertilization rates of immature mouse oocytes using Embryonic Stem Cell Conditioned Medium (ESCM). METHODS Germinal Vesicle (GV) stage oocytes were observed in 120 NMRI mice, aged 4-6 weeks. GV oocytes with or without cumulus cells were subjected to IVM in either ESCM, Embryonic Stem Cell Growth Medium (ESGM), or α-minimum essential medium (α-MEM). After recording the Metaphase II (MII) oocyte maturation rate, the oocytes were fertilized in vitro. The fertilization success rate was recorded after 24 hr. The embryos were maintained in potassium Simplex Optimization Medium (KSOM) for 96 hr and allowed to grow until the blastocyst stage. After recording developmental competence, they were transferred into the uteri of pseudopregnant mice and their birth rates were recorded. RESULTS No significant difference existed between the maturation rates in α-MEM (68.18%) and ESCM (64.67%; p>0.05), whereas this rate was significantly higher for both α-MEM and ESCM compared to ESGM (32.22%; p<0.05). A significant difference in IVF success rate existed for oocytes grown in α-MEM (69.44%), ESCM (61.53%), and ESGM (0%). A significantly higher developmental competence was observed at the blastocyst stage for oocytes grown in α-MEM (51.2%) compared to ESCM (35%; p<0.05). 17 days after embryo transfer into the uteri of pseudopregnant mice, there was a nonsignficant (p>0.05), similar birth rate between α-MEM and ESCM (47 vs. 40%). CONCLUSION ESCM is an effective medium for preantral follicle growth, oocyte maturation, and subsequent embryo development.