Calcium ionophore treatment after ICSI improves blastocyst development for male factor indications as well as patients with only a history of poor blastocyst development

Abstract

To determine whether calcium ionophore treatment after intracytoplasmic sperm injection (ICSI) can improve the blastocyst conversion rate in patients with male factor infertility or a history of poor blastocyst development whose partners have normal sperm parameters. Prospective intervention study. Between January 2015 and December 2016, patients with either male factor infertility (n=25) or only a history of poor blastocyst development whose partners have normal sperm parameters (n=34), were recruited for oocyte splits and calcium ionophore treatment. Immediately after ICSI, half of the metaphase 2 oocytes were randomly selected and treated with calcium ionophore solution (Calcium group; A23187 calcimycin, Sigma) for 15 minutes followed by a three-step washing protocol before in vitro culture. The remaining metaphase 2 sibling oocytes were untreated and placed directly into in vitro culture (Control group). All normally fertilized zygotes from both groups were sequentially cultured to the blastocyst stage. Transferable quality blastocysts were either biopsied for comprehensive chromosome screening (CCS) and vitrified, or vitrified intact, for a future frozen embryo transfer (FET). Statistical analysis included Student’s t-test, Fisher’s Exact and Chi square test where appropriate, with significance at P<0.05. On average 21.2±8.5 oocytes were retrieved per IVF cycle with mean maternal and paternal age of 36.9±4.5 and 39.9±5.8 years, respectively. Fertilization rates did not significantly differ between the sibling oocyte groups (67% Calcium versus 74% Control; ns). Likewise, cleavage rates to the 6-8 cell embryonic stage were comparable (97% with Calcium versus 96% Control; ns). In contrast further development to the blastocyst stage was significantly improved in the calcium ionophore treatment group (48%) when compared to controls (39%; P<0.05). In addition, there was a trend towards more blastocysts formed on Day 5 of embryonic development (21% Calcium versus 16% Control; P=0.06). A total of 38 cycles included CCS with a 43% euploidy rate from sibling oocytes treated with calcium ionophore compared to 44% euploidy rate for sibling oocyte untreated controls. To date, 29 patients have undergone an FET (n=12 SET Calcium group; n=12 SET Control group and n=5 DETs one blastocyst from each group) with an equivalent viable clinical pregnancy/live birth rate of 82.8% representing blastocysts from both groups. In our study, calcium ionophore treatment after ICSI resulted in increased rates of blastocyst formation with no impact on chromosome constitution or clinical pregnancy/live birth rates for patients with male factor infertility or a history of poor blastocyst development with normal sperm parameters.