Two parallel studies show gene editing can target mutant mitochondria in adult mice, providing an alternative path for drug developers to the controversial approach of modifying embryos.
In back-to-back papers published in Nature Medicine on Sept. 24, teams from the University of Cambridge and the University of Miami demonstrated that gene editing by zinc finger nucleases (ZFNs) and transcription activator-like effector nucleases (TALENs) can target mitochondrial genes in vivo in adult mice, raising the prospect the techniques could be used to treat a subset of mitochondrial diseases.
Previous studies have shown that ZFNs and TALENs can destroy mutant mitochondrial genes in mouse oocytes and single-cell embryos.
However, embryonic gene editing has been embroiled in controversy, and the method of mitochondrial replacement therapy (MRT), approved in the U.K. -- and colloquially referred to as “three-parent IVF” -- is outlawed in the U.S. (see “Editing Advantage” and “A Meeting About a Meeting”).
By providing proof of concept that virally delivered nucleases can target mutant mitochondrial genes after birth, the new findings bring the approaches under FDA’s gene therapy guidelines -- a step that could increase activity in the field.
Sangamo Therapeutics Inc. SVP and CTO Edward Rebar, an author on the Cambridge paper, believes the studies represent significant progress, despite the challenges of delivery and