Many mitochondrial diseases have been difficult to study and treat due to the inherent challenges in accessing mitochondrial DNA (mtDNA). Now, researchers have optimized mitochondrial-targeted compounds that can selectively modify the ratio of normal versus mutant mtDNA in patient-derived stem cells. This technology enables the creation of research models with varying mutation loads and demonstrates potential as a therapeutic strategy for reducing mutant mtDNA in patients, offering hope for mitochondrial disease treatment.