Artificial oocyte activation with Ca2+ ionophore improves reproductive outcomes in patients with fertilization failure and poor embryo development in the previous ICSI cycles
Authors: Ruan Jingling , Liang Liang Shanshan , Pan Jiaping , Chen Zhiqin , Teng Xiaoming 
Published: April 2023

Abstract
Research question: Does artificial oocyte activation (AOA) by calcium ionophore (ionomycin) improve the previous fertilization failure or poor embryo development of intracytoplasmic sperm injection (ICSI) account for male factor infertility or other infertility causes?
Design: This retrospective study involved 114 patients receiving ICSI-AOA in Shanghai First Maternity and Infant Hospital from January 2019 to December 2020 with previous ICSI fertilization failure or poor embryo development. Thirty minutes after ICSI, all metaphase II oocytes were exposed to 10 μmol/ L ionomycin for 10 minutes and cultured in vitro to Day3 or blastocyst stage. The previous ICSI cycles of the same patients without AOA were served as control group.The fertilization rates, cleavage rates, transferable embryo rates and blastocyst formation rates of the two groups were compared; Meanwhile, the clinical pregnancy, implantation rate and live birth rates were also compared to assess the efficiency and safety of AOA. Additionally, two subgroup analyses were performed in this study. According to the cause of infertility, patients were divided into six subgroups, and the activation cycle was compared with the previous ICSI cycle without AOA. Based on the reason for AOA, patients were divided into three subgroups for analysis. The fertilization rate, embryonic development potential and clinical outcome were compared among groups.
Result: Among 114 ICSI-AOA cycles, the fertilization rate, top-quality embryo rate, implantation rate, clinical pregnancy per patient and live birth rate per patient were improved significantly compared with previous ICSI cycles (p<0.05 to P< 0.001), and the miscarriage rate in the AOA group was significantly lower than that of the control group (p<0.001). In the AOA subgroups based on the cause of infertility, the fertilization rates of each subgroup were significantly improved compared with previous control cycles except for the mixed factor infertility subgroup (p<0.05 to p<0.001); However, compared with previous control cycle, there was no significant difference in the top-quality embryo rate among the subgroups except for the mixed factor infertility subgroup. In the AOA subgroups based on the reason for AOA, the fertilization rates of each subgroup were significantly increased compared with those in their previous ICSI cycle without AOA (p<0.001); However, there was no significant difference in the top-quality embryos rate. No significant improvement was found in the implantation rates and the clinical pregnancy rate in each subgroup except for poor embryo development subgroup. In the 114 AOA cycles, 35 healthy infants（21singletons and 7 twins）were delivered without major congenital birth defects and malformations.
Conclusion: This study showed AOA with calcium ionophore ionomycin can improve the reproductive outcomes of patients with previous fertilization failure and poor embryo development.