?? CRISPR-Base Editing for Mitochondrial Genome Correction in Inherited Disorders

Mitochondrial diseases are caused by mutations in mitochondrial DNA (mtDNA), leading to defects in cellular energy production and severe metabolic disorders. Unlike nuclear genome editing, correcting mtDNA mutations remains a major challenge due to the lack of a natural mitochondrial DNA repair system and the difficulty in providing traditional CRISPR components. However, recent breakthroughs in CRISPR base editing provide a promising solution for precise mitochondrial genome correction, bringing new hope for the treatment of inherited mitochondrial diseases.

One of the major obstacles to mitochondrial genome editing is the inability to use CRISPR-Cas9 because mitochondria lack homology-directed repair (HDR) machinery. Conventional CRISPR systems rely on double-strand breaks (DSBs), which mitochondria cannot effectively repair, leading to unexpected consequences. To overcome this problem, researchers developed a DddA-derived cytosine base editor (DdCBE), which is able to directly convert C?G to T?A in mitochondrial DNA without DSBs or HDR.

Recent studies have shown that DdCBE and other base editors are highly effective in precisely correcting pathogenic mitochondrial DNA mutations in cells and animal models. These systems utilize engineered bacterial deaminases fused to mitochondrial targeting peptides, allowing for targeted single-base modifications within the mitochondrial genome. The technology has shown promising results in treating Leigh syndrome, MELAS (mitochondrial encephalopathy, lactic acidosis, and stroke-like episodes), and Leber hereditary optic neuropathy (LHON), which previously lacked effective treatment options.

In addition to mutation correction, researchers are exploring improved mitochondrial base editor delivery methods to ensure greater efficiency and specificity. Advances in viral and non-viral delivery systems, AI-driven guide RNA design, and engineered base editors are improving the safety and precision of CRISPR-mediated mitochondrial genome correction. These efforts are critical to making mitochondrial gene therapy clinically feasible.

Looking ahead, CRISPR-based mitochondrial genome editing has great potential to revolutionize mitochondrial medicine. As base editing tools continue to advance, they bring us closer to personalized cures for mitochondrial diseases, bringing transformative breakthroughs in precision medicine.?

References

[1] Rui Bi et al., The Innovation 2022 (https://doi.org/10.1016/j.xinn.2022.100329)

[2] Yanyan Gao et al., Cytotherapy 2024 (https://doi.org/10.1016/j.jcyt.2023.10.004)