Early administration of carvedilol protected against doxorubicin-induced cardiomyopathy

This study tested for the benefits of early administration of carvedilol as protection against doxorubicin (DOX)-induced cardiomyopathy. Thirty male, adult B6 mice were categorized into group 1 (untreated control), group 2 [DOX treatment (15 mg/every other day for 2 weeks, i.p.], and group 3 [carvedilol (15 mg/kg/d, from day 7 after DOX treatment for 28 days)], and euthanized by day 35 after DOX treatment. By day 35, the left ventricular ejection fraction (LVEF) was significantly lower in group 2 than in groups 1 and 3, and significantly lower in group 3 than in group 1, whereas the left ventricular (LV) end-diastolic and LV endsystolic dimensions showed an opposite pattern to the LVEF among the three groups. The protein expressions of fibrotic (Smad3, TGF-β), apoptotic (BAX, cleaved caspase 3, PARP), DNA damage (γ-H2AX), oxidative stress (oxidized protein), mitochondrial damage (cytosolic cytochrome-C), heart failure (brain natriuretic peptide), and hypertrophic (β-MHC) biomarkers of the LV myocardium showed an opposite pattern to the LVEF among the three groups. The protein expressions of antifibrotic (BMP-2, Smad1/5), α-MHC, and phosphorylated-Akt showed an identical pattern to the LVEF among the three groups. The microscopic findings of fibrotic and collagen-deposition areas and the numbers of γ-H2AX⁺ and 53BP1⁺ cells in the LV myocardium exhibited an opposite pattern, whereas the numbers of endothelial cell (CD31⁺, vWF⁺) markers showed an identical pattern to the LVEF among the three groups. Cardiac stem cell markers (C-kit⁺ and Sca-1⁺ cells) were significantly and progressively increased from group 1 to group 3. Additionally, the in vitro study showed carvedilol treatment significantly inhibited DOX-induced cardiomyoblast DNA (CD90/ XRCC1⁺, CD90/53BP1⁺, and r-H2AX⁺ cells) damage. Early carvedilol therapy protected against DOX-induced DNA damage and cardiomyopathy.