Precise base editing for dystrophin restoration in the mdx model of Duchenne Muscular Dystrophy

Duchenne Muscular Dystrophy is an X-linked recessive disease characterized by progressive muscle wasting due to the absence of dystrophin. The latter is a protein located at the sarcolemma linking the inner cytoskeleton to the extracellular matrix, whose role is to relieve the mechanical stress generated at each muscle contraction. The pathology originates at a genetic level from mutations in the DMD gene negatively impacting the production of the functional protein and ultimately leading to loss of muscle structure and function. Current available treatments aim at ameliorating the clinical manifestations, modulating the secondary effects of the disorder, while therapeutic strategies able to permanently address the genetic cause of the disease still remain limited. For this reason, base editing emerges as a potential approach to edit the mutations of the DMD gene. The pathological features that distinguish DMD patients are recapitulated in the widely characterized mdx mouse, carrying a nonsense mutation in exon 23, leading to the absence of dystrophin in the muscles and, therefore, representing a valuable and reliable preclinical model to analyze DMD. In this study, we develop a gene editing strategy aiming at performing exon skipping to restore dystrophin expression in mdx mice. The approach exploits base editing to exclude the mutation-carrying exon 23 from the DMD transcript, restoring the open reading frame. The strategy was evaluated in vitro as a preclinical approach for future application in the mdx mouse model.