Characterization of the Cardiac Structure and Function of Conscious D2.B10-Dmd^mdx/J (D2-mdx) mice from 16-17 to 24-25 Weeks of Age

Duchenne muscular dystrophy (DMD) is the most common form of muscle degenerative hereditary disease. Muscular replacement by fibrosis and calcification are the principal causes of progressive and severe musculoskeletal, respiratory, and cardiac dysfunction. To date, the D2.B10-Dmd(mdx)/J (D2-mdx) model is proposed as the closest to DMD, but the results are controversial. In this study, the cardiac structure and function was characterized in D2-mdx mice from 16-17 up to 24-25 weeks of age. Echocardiographic assessment in conscious mice, gross pathology, and histological and cardiac biomarker analyses were performed. At 16-17 weeks of age, D2-mdx mice presented mild left ventricular function impairment and increased pulmonary vascular resistance. Cardiac fibrosis was more extended in the right ventricle, principally on the epicardium. In 24-25-week-old D2-mdx mice, functional and structural alterations increased but with large individual variation. High-sensitivity cardiac Troponin T, but not N-terminal pro-atrial natriuretic peptide, plasma levels were increased. In conclusion, left ventricle remodeling was mild to moderate in both young and adult mice. We confirmed that right ventricle epicardial fibrosis is the most outstanding finding in D2-mdx mice. Further long-term studies are needed to evaluate whether this mouse model can also be considered a model of DMD cardiomyopathy.