The establishment of appropriate methods for egg-activation by human PLCZ1 RNA injection into human oocyte

•Pattern of Ca2+ oscillations induced by several egg-activating methods is examined in human oocytes.•Optimal concentration of PLCZ1 RNA for embryo development is determined.•The characteristics of Ca2+ oscillations after PLCZ1 RNA injection are similar to that after ICSI treatment.•Developmental rate of embryo activated by PLCZ1 RNA is the highest, compared with ionomycin and electrical stimulation.

Phospholipase C-zeta (PLCZ1), a strong candidate of egg-activating sperm factor, can induce Ca2+ oscillations and cause egg activation. For the application of PLCZ1 to clinical use, we examined the pattern of Ca2+ responses and developmental rate by comparing PLCZ1 RNA injection methods with the other current methods, such as cytosolic aspiration, electrical stimulation and ionomycin treatment in human oocytes. We found that the pattern of Ca2+ oscillations after PLCZ1 RNA injection exhibited similar characteristics to that after ICSI treatment. We also determined the optimal concentration of human PLCZ1 RNA to activate the human oocytes. Our findings suggest that human PLCZ1 RNA is a better therapeutic agent to rescue human oocytes from failed activation, leading to normal and efficient development.

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