Phenotypic features of genetically modified DMD-X^KOX^WT pigs

Duchenne muscular dystrophy (DMD) is a hereditary neuromuscular disorder caused by mutation in the dystrophin gene (DMD) on the X chromosome. Female DMD carriers occasionally exhibit symptoms such as muscle weakness and heart failure. Here, we investigated the characteristics and representativeness of female DMD carrier (DMD-X^KOX^WT) pigs as a suitable disease model.

In vitro fertilization using sperm from a DMD-X^KOY↔X^WTX^WT chimeric boar yielded DMD-X^KOX^WT females, which were used to generate F2 and F3 progeny, including DMD-X^KOX^WT females. F1-F3 piglets were genotyped and subjected to biochemical analysis for blood creatine kinase (CK), aspartate aminotransferase, and lactate dehydrogenase. Skeletal muscle and myocardial tissue were analyzed for the expression of dystrophin and utrophin, as well as for lymphocyte and macrophage infiltration.

DMD-X^KOX^WT pigs exhibited various characteristics common to human DMD carrier patients, namely, asymptomatic hyperCKemia, dystrophin expression patterns in the skeletal and cardiac muscles, histopathological features of skeletal muscle degeneration, myocardial lesions in adulthood, and sporadic death. Pathological abnormalities observed in the skeletal muscles in DMD-X^KOX^WT pigs point to a frequent incidence of pathological abnormalities in the musculoskeletal tissues of latent DMD carriers. Our findings suggest a higher risk of myocardial abnormalities in DMD carrier women than previously believed.

We demonstrated that DMD-X^KOX^WT pigs could serve as a suitable large animal model for understanding the pathogenic mechanism in DMD carriers and developing therapies for female DMD carriers.