Cumulus coculture and cumulus-aided embryo transfer increases pregnancy rates in patients undergoing in vitro fertilization.

OBJECTIVE To evaluate the effect of the use of cumulus-aided embryo transfer on pregnancy rates. To study the proximity of expanded cumulus cells to the developing embryo. To document by light microscopy the anchoring of day 3 to day 4 embryos by the expanded cumulus cells. To demonstrate by transmission electron microscopy the cellular activity of the expanded cumulus cells. To evaluate the expression of growth factors (vascular endothelial growth factor, interleukin-6, insulin-like growth factor I) that are secreted by the cumulus cells. DESIGN A comparative study of a group of women undergoing cumulus coculture and cumulus-aided embryo transfer, with those who underwent cumulus coculture but did not undergo cumulus-aided embryo transfer. The endpoint was the achievement of pregnancy. SETTING Department of Infertility Management and Assisted Reproduction, Jaslok Hospital and Research Centre, Mumbai, India. PATIENT(S) Five hundred seventeen women undergoing treatment for infertility using intracytoplasmic sperm injection and embryo transfer and fulfilling set criteria. To validate our initial results, we conducted a similar study on 208 women where randomization was performed. INTERVENTION(S) Embryos were cocultured with the patient's own cumulus cells and were transferred into the uterus with approximately 30 microL of the expanded cumulus cells. MAIN OUTCOME MEASURE(S) Pregnancy, implantation, and multiple gestation rates. RESULT(S) Our study demonstrated a significant increase in the implantation rate in the study group (group A) of 25.6% versus 14.5% in the control group (group B) and a significant increase in the pregnancy rate in the study group (group A) of 47.6% versus 34% achieved in the control group (group B). Although the incidence of multiple gestation was similar (38.6% in the study group and 32.9% in the control group), the higher-order multiple gestation rate was significantly more in the study group as compared with the control group (18.1% vs. 2.4%). Similar pregnancy and implantation rates were observed in the randomized study. CONCLUSION(S) This study demonstrates the efficacy of cumulus-aided embryo transfer, using autologous cumulus cells. It indicates a significant increase in implantation and pregnancy rates. The results suggest that cumulus cells play an important role in embryonic development, and that they may provide a mechanism to improve embryo-uterine adhesion by physical proximity, and by secreting cytokines and growth factors required to aid the implantation process.