Reduction of mtDNA heteroplasmy in mitochondrial replacement therapy by inducing forced mitophagy

Area of Science:

• Genetics
• Cell Biology
• Reproductive Medicine

Background:

• Mitochondrial replacement therapy (MRT) aims to prevent the transmission of mitochondrial DNA (mtDNA) diseases.
• A significant challenge in MRT is the carryover of donor mtDNA, potentially leading to pathogenic levels due to selective replication and genetic drift.

Purpose of the Study:

• To develop a method for reducing mtDNA heteroplasmy in embryos undergoing MRT.
• To assess the efficacy and safety of forced mitophagy for eliminating donor mtDNA carryover.

Main Methods:

• Pre-labelling the outer mitochondrial membrane of donor zygotes with mRNA encoding a transmembrane peptide fused to an autophagy receptor.
• Inducing targeted degradation of labelled mitochondria via forced mitophagy.
• Evaluating mtDNA carryover and offspring characteristics in HeLa cells, mouse embryos, and human embryos.

Main Results:

• Forced mitophagy effectively reduced mtDNA carryover in reconstructed embryos post-MRT.
• Offspring mice exhibited negligible effects on growth, reproduction, and behavior.
• The technique demonstrated safety and efficacy across different model systems.

Conclusions:

• Forced mitophagy is a viable strategy to mitigate mtDNA carryover during MRT.
• This approach enhances the clinical feasibility of MRT for preventing mitochondrial genetic diseases.
• The method has potential applications in other nuclear transfer techniques.