Novel rat model of multiple mitochondrial dysfunction syndromes (MMDS) complicated with cardiomyopathy

BACKGROUND: Multiple mitochondrial dysfunction syndromes (MMDS) presents as complex mitochondrial damage, thus impairing a variety of metabolic pathways. Heart dysplasia has been reported in MMDS patients; however, the specific clinical symptoms and pathogenesis remain unclear. More urgently, there is a lack of an animal model to aid research. Therefore, we selected a reported MMDS causal gene, Isca1, and established an animal model of MMDS complicated with cardiac dysplasia. METHODS: The myocardium‐specific Isca1 knockout heterozygote (Isca1 HET) rat was obtained by crossing the Isca1 conditional knockout (Isca1 cKO) rat with the α myosin heavy chain Cre (α‐MHC‐Cre) rat. Cardiac development characteristics were determined by ECG, blood pressure measurement, echocardiography and histopathological analysis. The responsiveness to pathological stimuli were observed through adriamycin treatment. Mitochondria and metabolism disorder were determined by activity analysis of mitochondrial respiratory chain complex and ATP production in myocardium. RESULTS: ISCA1 expression in myocardium exhibited a semizygous effect. Isca1 HET rats exhibited dilated cardiomyopathy characteristics, including thin‐walled ventricles, larger chambers, cardiac dysfunction and myocardium fibrosis. Downregulated ISCA1 led to deteriorating cardiac pathological processes at the global and organizational levels. Meanwhile, HET rats exhibited typical MMDS characteristics, including damaged mitochondrial morphology and enzyme activity for mitochondrial respiratory chain complexes Ⅰ, Ⅱ and Ⅳ, and impaired ATP production. CONCLUSION: We have established a rat model of MMDS complicated with cardiomyopathy, it can also be used as model of myocardial energy metabolism dysfunction and mitochondrial cardiomyopathy. This model can be applied to the study of the mechanism of energy metabolism in cardiovascular diseases, as well as research and development of drugs.