А new technology for maturation of human oo cytes by injection of extracellular vesicles of follicular donor fluid under the shiny shell of the female gamete

Background . In assisted reproductive technology (ART) programs, not all oocytes obtained during transvag inal puncture (TVP) are suitable for fertilization, as not all of them are at MII stage. Oocytes at germinal vesicle (GV) and MI stages are discarded because, after cumulus cells (CC) removal, their maturation and fertilization become impossible. Study proposes method for oocytes maturing by introducing extracellular vesicles (EVs) from follicular fluid (FF) into the perivitelline space. Objective . To evaluate the clinical feasibility of GV/MI oo cytes maturing technology without cumulus cells by injecting donor FF EVs under the zona pellucida. Materials and methods . FF (5 ml) was collected from 4 donors. EVs were isolated using sequential centrifugation. Portion of EVs was analyzed using Nanoparticle Tracking Analysis (NTA), while another portion was examined using transmission electron microscopy (TEM). Total of 53 immature oocytes were selected for the main group and 18 for the control group. Donor FF EVs were injected 4 hours after CC removal by introducing EVs suspension under zona pellucida. After 17 hours, oocyte maturity was assessed in both groups. Results . Oocytes maturation rate in the main group was statistically significantly higher than in the control group, indicating the potential effectiveness of the EV-IVM method for maturing GV-stage oocytes. Conclusion . Obtained data provide hope for the development of a new method for in vitro oocyte maturation.