bioRxiv : the preprint server for biologyOct 25, 2026

Virus-like particles carrying mRNA enable accurate mitochondrial DNA editing in cells and living organisms

CRISPR Gene Editing Weekly Brief ↗PubMed ↗DOI ↗OA ↗

Updated Oct 26, 2026

Abstract

mtBE-VLPs achieved over 50% base editing efficiency across multiple target mtDNA loci in cultured cells.

Mitochondrial DNA base editors (mtBEs) can be hindered by significant off-target effects when delivered via plasmid DNA or viral methods.
Engineered mRNA-packaging virus-like particles (VLPs) improved the efficiency of mtBE cargo delivery compared to traditional methods.
A novel strategy to reduce mtBE expression in VLP producer cells increased editing efficiencies for certain mtBEs by 7.1-fold.
mtBE-VLPs showed equivalent on-target editing but significantly lower off-target effects (23- to 41-fold reduction) compared to plasmid delivery.
In mouse embryonic fibroblasts, mtBE-VLPs installed a pathogenic mtDNA mutation with 88% efficiency and corrected a mutation in a human cell line with 41% efficiency.
A single subretinal injection of mtBE-VLPs resulted in an average of 12% mtDNA base editing in the mouse retinal pigment epithelium.

Simplified

Mitochondrial DNA (mtDNA) base editors (mtBEs) are promising tools for studying and correcting pathogenic mtDNA mutations. However, the application of mtBEs is often hindered by substantial mtDNA-wide off-target editing that accumulates with prolonged mtBE expression resulting from plasmid DNA or viral delivery. To overcome this limitation, we developed mtBE-VLPs, a virus-like-particle (VLP) platform for transiently delivering mtBEs in vitro and in vivo with minimal off-target effects. While canonical protein-packaging VLPs yielded undetectable mtDNA base editing, engineered mRNA-packaging VLPs enabled efficient but transient mtBE cargo delivery. By iteratively engineering mRNA-packaging VLP compositions, we improved mtBE-VLP-mediated base editing efficiencies from less than 1% to greater than 50% across multiple target mtDNA loci in bulk populations of treated cultured cells. To further improve the packaging and delivery of certain mtBEs, we developed a strategy to selectively reduce mtBE cargo expression in VLP producer cells but not transduced cells, which increased VLP-mediated base editing efficiencies for certain mtBEs by 7.1-fold. Compared to plasmid DNA delivery in vitro , mtBE-VLPs exhibited equivalent on-target editing but 23- to 41-fold lower mtDNA-wide off-target editing, highlighting the improved editing specificity offered by transient mtBE delivery. mtBE-VLPs efficiently installed a pathogenic mtDNA mutation in mouse embryonic fibroblasts (88% efficiency) and corrected a pathogenic mtDNA mutation in a human patient-derived cell line (41% efficiency). Additionally, a single subretinal injection of mtBE-VLPs yielded 6-20% (average 12%) mtDNA base editing in the mouse retinal pigment epithelium with minimal mtDNA-wide off-target editing. These findings establish mRNA-packaging mtBE-VLPs as promising vehicles for efficient and precise mitochondrial base editing via transient mtBE delivery.

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Virus-like particles carrying mRNA enable accurate mitochondrial DNA editing in cells and living organisms

Abstract

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