In vivo gene editing in dystrophic mouse muscle and muscle stem cells

TLDR

Frame‑disrupting mutations in the DMD gene compromise myofiber integrity and drive muscle deterioration in Duchenne muscular dystrophy, while exon removal can generate an in‑frame mRNA that encodes a truncated but functional dystrophin protein. The study aimed to develop and test a direct gene‑editing approach that deletes exon 23 to recover dystrophin expression in the mdx mouse model of DMD. AAV‑delivered CRISPR‑Cas9 with paired guide RNAs flanking exon 23 excised the intervening DNA, restoring the Dmd reading frame in myofibers, cardiomyocytes, and muscle stem cells after local or systemic delivery. AAV‑CRISPR treatment partially restored muscle function and generated a pool of endogenously corrected myogenic precursors in mdx mouse muscle.

Abstract

Frame-disrupting mutations in the DMD gene, encoding dystrophin, compromise myofiber integrity and drive muscle deterioration in Duchenne muscular dystrophy (DMD). Removing one or more exons from the mutated transcript can produce an in-frame mRNA and a truncated, but still functional, protein. In this study, we developed and tested a direct gene-editing approach to induce exon deletion and recover dystrophin expression in the mdx mouse model of DMD. Delivery by adeno-associated virus (AAV) of clustered regularly interspaced short palindromic repeats (CRISPR)-Cas9 endonucleases coupled with paired guide RNAs flanking the mutated Dmd exon23 resulted in excision of intervening DNA and restored the Dmd reading frame in myofibers, cardiomyocytes, and muscle stem cells after local or systemic delivery. AAV-Dmd CRISPR treatment partially recovered muscle functional deficiencies and generated a pool of endogenously corrected myogenic precursors in mdx mouse muscle.