In vitro maturation of human oocytes maintaining good development potential for rescue intracytoplasmic sperm injection with fresh sperm

Abstract

BACKGROUND The outcomes of the use of commercial in vitro maturation (IVM) medium toculture immature oocytes obtained from conventional ovulation induction,followed by rescue intracytoplasmic sperm injection (RICSI), are not ideal. It isthus difficult to widely adopt this approach in clinical practice. Therefore, it isnecessary to explore methods for improving the clinical outcome of IVM.AIMTo study the effect of sperm on the developmental potential of in vitro-maturedoocytes in conventional culture.METHODSThis was a retrospective study of patients whose immature oocytes wereharvested from conventional oocyte stimulation cycles and underwent ICSI at ourhospital between June 2018 and August 2020. RICSI was performed using spermcollected on the day of oocyte harvest (old) and sperm collected on the day ofRICSI (fresh) and oocytes matured in vitro after 24 h of culture in conventionalmedium. The rates of in vitro oocyte maturation, normal fertilization, normalcleavage, day-3 top-quality embryos, and useful blastocyst formation werecompared between the two groups.RESULTSIn total, 102 germinal vesicle (GV)-stage immature oocytes were cultured in theold sperm group. In the fresh sperm group, 122 GV-stage immature oocytes werecollected and cultured in vitro for 24 h. There were no significant differences in thegeneral conditions of males and females between the two groups (P > 0.05). Theoocyte maturation, normal fertilization, and normal cleavage rates of the old and fresh groups were 51.0% vs 55.7%, 61.5% vs 64.7%, and 93.8% vs 93.2%, respectively. None of the rates differed significantly (P > 0.05) between the two groups. However, the day-3 top-quality embryo and useful blastocyst rates of the old and fresh sperm groups were 16.6% vs 63.4%; 6.67% vs 34.6%, respectively. The day-3 top-quality embryos and useful blastocyst rates of the old spermgroup were significantly lower than those of the fresh group (P < 0.05).