Mitochondrial replacement therapy in reproductive medicine

Area of Science:

• Reproductive biology and genetics
• Mitochondrial medicine
• Assisted reproductive technologies

Background:

• Mitochondrial dysfunction is linked to various diseases and age-related infertility.
• Inherited mitochondrial DNA (mtDNA) defects can be passed to subsequent generations.
• Current treatments for mitochondrial diseases are limited, necessitating preventative strategies.

Purpose of the Study:

• To review and compare different mitochondrial replacement therapies (MRT) for preventing the transmission of mtDNA defects.
• To evaluate the efficacy and potential of MRT in addressing age-related infertility.
• To explore the application of MRT in oocytes and zygotes, including pronuclear (PNT), spindle (ST), and polar body (PBT) transfer techniques.

Main Methods:

• Review of existing literature on various MRT techniques (PNT, ST, PBT) in different species (mice, primates, human embryos).
• Analysis of mtDNA carryover rates associated with each MRT method.
• Assessment of developmental outcomes and ethical considerations for each technique.

Main Results:

• Pronuclear transfer (PNT) shows high mtDNA carryover in mice but low levels in human embryos, with ethical concerns regarding donor embryo destruction.
• Spindle transfer (ST) in primates supports normal development to adulthood with low mtDNA carryover.
• Polar body transfer (PBT), when combined with PNT or ST in mice, may enhance the yield of reconstructed embryos with reduced mtDNA carryover.

Conclusions:

• Mitochondrial replacement therapies offer a potential strategy to prevent the inheritance of mtDNA defects.
• MRT, particularly ST and PBT, demonstrates promise for improving reproductive outcomes in cases of mitochondrial dysfunction and age-related infertility.
• Further research and ethical considerations are necessary to optimize MRT techniques for clinical application in assisted reproduction.