Artificial oocyte activation: physiological, pathophysiological and ethical aspects

Area of Science:

• Reproductive Biology
• Developmental Biology
• Assisted Reproductive Technologies

Background:

• Intra-cytoplasmic sperm injection (ICSI) failure can occur in infertile couples with poor oocyte yield and abnormal semen parameters.
• Oocyte activation deficiency (AOD), often due to insufficient phospholipase C-zeta (PLCζ), is a key factor in ICSI failure.
• Calcium (Ca2+) oscillations are crucial for oocyte activation, normally triggered by sperm factors like PLCζ.

Purpose of the Study:

• To review the role of Ca2+ oscillations in mammalian oocyte activation.
• To summarize the current evidence on the use of artificial oocyte activation (AOA) methods to overcome ICSI failure.
• To discuss the physiological, pathophysiological, and ethical considerations of AOA.

Main Methods:

• This is a narrative review synthesizing existing research on oocyte activation and AOA.
• The review examines studies involving both human and animal models.
• Key factors like phospholipase C-zeta (PLCζ) and artificial stimulants are discussed in relation to Ca2+ oscillations.

Main Results:

• Cytosolic Ca2+ oscillations in mammalian eggs result from periodic Ca2+ release from intracellular stores.
• Both natural activators like PLCζ and artificial stimulants can induce Ca2+ oscillations for AOA.
• Various artificial agents, including chemical compounds and electrical pulses, are employed in laboratories to induce AOA.

Conclusions:

• Artificial oocyte activation (AOA) is explored as a method to address oocyte activation deficiency (AOD) and improve ICSI success rates.
• While AOA can induce necessary Ca2+ oscillations, potential risks, particularly epigenetic malformations, warrant further investigation.
• More research is needed to determine the safety and efficacy of AOA as a clinical procedure to overcome ICSI failure.