Cardiac dysfunction and pathology in the dystrophin and utrophin-deficient mouse during development of dilated cardiomyopathy

Cardiac involvement in Duchenne muscular dystrophy is asymptomatic until function is severely affected. Little is known about its evolution, and few animal models are available to study potential treatments. We therefore examined cardiac function and pathology in mdx/utrn−/− dystrophin/utrophin-deficient mice. Decreased left ventricular fractional shortening and ejection fraction, as well as increased end-diastolic volume, left ventricle dilation, and thinning of the ventricular wall and septum develop by 15 weeks. Fibrosis is also detected in the outer region of both ventricle walls and the septum and ultrastructure analysis revealed abnormalities in mitochondrial organization, size, and shape. The functional changes observed are comparable to the evolution of dilated cardiomyopathy in Duchenne muscular dystrophy, indicating that mdx/utrn−/− dystrophin/utrophin-deficient mice are a possible phenotypic model for cardiomyopathy in Duchenne muscular dystrophy.