P–279 Effect of Ca2+ ionophore A23187 (calcymicin) on fertilization rates, embryo development and pregnancy in human assisted reproduction cycles
Authors: Lópe. Ruiz G , Olmed. Illueca C , Bare. Gómez M , Roy. Bolea S , Aba. d. Velasco L , Cueva. Saiz I 
Published: August 2021

Abstract

Study question
Does Calcymicin improve reproductive outcomes of ICSI cycles in cases of fertilization failure and/or embryo blockage indications?

Summary answer
The application of the Calcymicin after ICSI improves reproductive outcomes, especially in cases with clinical indication of fertilization failure.

What is known already
According to the bibliography, deficiencies in the oocyte activation process frequently lead to failed ICSI cycles, and these can be corrected by increasing initial levels of calcium (Ca2+) in the oocyte using assisted oocyte activation techniques (AOA), such as the use of Ca2+ ionophores. Ca2+ Ionophores have been shown to trigger an initial Ca2+ spike in the ooplasm that activates Ca2+/Calmodulin dependent protein kinase II, which initiates the cascade of cellular events leading to oocyte activation. Previous results suggest that Ca2+ ionophore treatment can give live offspring after failed ICSI cycles.

Study design, size, duration
270 oocytes collected from 17 patients who presented cycles with low fertilization rates and/or embryo blockage or poor quality embryos (according to ASEBIR’s embryo classification criteria) were retrospectively analyzed. Oocytes were divided into two groups, a control group that underwent conventional IVF/ICSI and another group that underwent an ICSI cycle with AOA. Study groups were defined according to clinical indications and subgroups according to AOA or control. All data were collected from 2017 until 2020.

Participants/materials, setting, methods
Among the 270 oocytes of the study sample, 142 belonged to the control group and 128 belonged to the AOA group. The AOA group oocytes were activated for 15 minutes immediately after ICSI using a prepared solution containing the Ca2+ ionophore A23187, CultActive© (Gynemed, Germany). Fertilization rate and type, blastocyst formation rate, blastocyst quality, embryo kinetics, and pregnancy rates were analyzed, all of them were compared to FIV/ICSI cycles without oocyte activation (control group).

Main results and the role of chance
In the analyses of the whole sample of oocytes, the AOA treatment gave a fertilization rate of 72.5%, which was significantly higher compared to 53.8% of the control cycles (p = 0.002). Good quality blastocysts and pregnancy rates were also significantly higher than the control (p = 0.01). In the group with an indication of fertilization failure, a significantly higher fertilization rate was recorded compared to the control (65% and 33%, respectively). A higher rate of abnormal embryos with three pronuclei was also found compared to the control (p &lt; 0.001). There were no significant differences in blastocyst formation rates, quality, or embryo kinetics (p &gt; 0.05). In the group with an indication of embryo blockage/poor embryo quality, a significantly higher rate of good quality blastocysts and lower blastulation time were recorded compared to the control (p &lt; 0.05).

Limitations, reasons for caution
The safety of the AOA technique with Ca2+ ionophore has not been fully demonstrated. In our study, none of the newborns had malformations, and gestational weeks and birth weights were normal. However, further studies on the safety of this technique are needed to implement it routinely in human reproduction clinics.
Wider implications of the findings: According to these findings, an increase in the initial levels of calcium in the oocyte through the application of the Ca2+ ionophore A23187 after ICSI improves the results of failed assisted reproduction cycles, especially in the case of those diagnosed with fertility failure, which is a clear indication for AOA.

Trial registration number
Not applicable