Meiosis Resumption of Immature Human Oocytes following Treatment with Calcium Ionophore .

Objective: maturation (IVM) of human oocytes is used to induce meiosis progression in immature retrieved oocytes. Calcium (Ca) has a central role in oocyte physiology. Passage through meiosis phase to another phase is controlled by increasing intracellular Ca. Therefore, the current research was conducted to evaluate the role of calcium ionophore (CI) on human oocyte IVM.

Materials And Methods: In this clinical trial study, immature human oocytes were obtained from 216 intracytoplasmic sperm injection (ICSI) cycles. After ovarian stimulation, germinal vesicle (GV) stage oocytes were collected and categorized into two groups: with and without 10 μM CI treatment. Next, oocyte nuclear maturation was assessed after 24-28 hours of culture. Real-time reverse transcription polymerase chain reaction (RT-PCR) was used to assess the transcript profile of several oocyte maturation-related genes ( and ) and apoptotic-related genes (, and ). Oocyte glutathione (GSH) and reactive oxygen species (ROS) levels were assessed using Cell Tracker Blue and 2',7'-dichlorodihydrofluorescein diacetate (H2DCFDA) fluorescent dye staining. Oocyte spindle configuration and chromosome alignment were analysed by immunocytochemistry.

Results: The metaphase II (MII) oocyte rate was higher in CI-treated oocytes (73.53%) compared to the control (67.43%) group, but this difference was not statistically significant (P=0.13). The mRNA expression profile of oocyte maturation-related genes ( and ) (P<0.05) and the anti-apoptotic gene was remarkably up-regulated after treatment with CI (P=0.001). The pro-apoptotic and relative expression levels did not change significantly. The CI-treated oocyte cytoplasm had significantly higher GSH and lower ROS (P<0.05). There was no statistically significant difference in meiotic spindle assembly and chromosome alignment between CI treatment and the control group oocytes.

Conclusion: The finding of the current study supports the role of CI in meiosis resumption of human oocytes. (Registration Number: IRCT20140707018381N4).