Mitochondrial replacement therapy (MRT) has been used to prevent maternal transmission of disease-causing mutations in mitochondrial DNA (mtDNA). However, because MRT requires nuclear transfer, it carries the risk of mtDNA carryover and hence of the reversion of mtDNA to pathogenic levels owing to selective replication and genetic drift. Here we show in HeLa cells, mouse embryos and human embryos that mtDNA heteroplasmy can be reduced by pre-labelling the mitochondrial outer membrane of a donor zygote via microinjection with an mRNA coding for a transmembrane peptide fused to an autophagy receptor, to induce the degradation of the labelled mitochondria via forced mitophagy. Forced mitophagy reduced mtDNA carryover in newly reconstructed embryos after MRT, and had negligible effects on the growth curve, reproduction, exercise capacity and other behavioural characteristics of the offspring mice. The induction of forced mitophagy to degrade undesired donor mtDNA may increase the clinical feasibility of MRT and could be extended to other nuclear transfer techniques.

线粒体替代疗法 (MRT) 已被用于预防线粒体 DNA (mtDNA) 中致病突变的母体传播。然而，由于 MRT 需要核移植，它具有携带 mtDNA 的风险，因此由于选择性复制和遗传漂移，mtDNA 会恢复到致病水平。在这里，我们在 HeLa 细胞、小鼠胚胎和人类胚胎中显示，可以通过显微注射预标记供体受精卵的线粒体外膜来减少 mtDNA 异质性，该 mRNA 编码与自噬受体融合的跨膜肽，以诱导降解通过强制线粒体自噬标记的线粒体。强制线粒体自噬减少了 MRT 后新重建胚胎中的 mtDNA 残留，对生长曲线、繁殖、后代小鼠的运动能力和其他行为特征。诱导强迫线粒体自噬以降解不需要的供体 mtDNA 可能会增加 MRT 的临床可行性，并且可以扩展到其他核移植技术。