Post-daunorubicin treatment effects on cardiovascular function in the Ts65Dn mouse model of Down syndrome

Adults with Down syndrome (DS) are two times more likely to be diagnosed with chronic heart failure post-anthracycline chemotherapy compared to age and sex-matched adults without DS. They have an elevated lifetime risk of cardiovascular diseases, increasing their likelihood of anthracycline-induced chronic cardiovascular toxicity. We investigated the chronic effects of daunorubicin on the cardiovascular system of the adult Ts65Dn mouse model of DS compared to wild type euploid mice (WT). WT and Ts65Dn mice received two doses of 2mg/kg or 4mg/kg of daunorubicin or saline and were monitored for up to 117 days. Cardiac and vascular function were evaluated using left ventricular catheterization, histology, pulse wave velocity, and cardiac troponin tests. Survival significantly decreased in the Ts65Dn 4mg/kg group compared to saline controls (p<0.001). Further experiments were carried out with the saline and 2mg/kg groups, which exhibited lower mortality, more consistent with chronic toxicity. Body weight (p=0.001), end-diastolic pressure (p=0.016), and left ventricular mass (p=0.021) decreased in treated mice. The effect of treatment differed significantly between strains for ejection fraction (p=0.029). Pulse wave velocity increased over time (p<0.001). A significant interaction between treatment and strain was observed for collagen in both the left ventricles and thoracic aorta (p=0.002 and p<0.001, respectively). There was a strain difference for cardiac troponin I, indicating an increase in Ts65Dn mice (p=0.020). Daunorubicin treatment results in a distinct cardiovascular remodeling phenotype in Ts65Dn mice. More mechanistic studies are warranted to outline the pathophysiology of anthracycline cardiovascular toxicity in DS.