Browsing by Subject "cardiac regeneration"

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    Cell Cycle–Mediated Cardiac Regeneration in the Mouse Heart
    (Springer, 2019) Eghbali, Arash; Dukes, Austin; Toischer, Karl; Hasenfuss, Gerd; Field, Loren J.; Medicine, School of Medicine
    Purpose of Review Many forms of heart disease result in the essentially irreversible loss of cardiomyocytes. The ability to promote cardiomyocyte renewal may be a promising approach to reverse injury in diseased hearts. The purpose of this review is to describe the impact of cardiomyocyte cell cycle activation on cardiac function and structure in several different models of myocardial disease. Recent Findings Transgenic mice expressing cyclin D2 (D2 mice) exhibit sustained cardiomyocyte renewal in the adult heart. Earlier studies demonstrated that D2 mice exhibited progressive myocardial regeneration in experimental models of myocardial infarction, and that cardiac function was normalized to values seen in sham-operated litter mates by 180 days post-injury. D2 mice also exhibited markedly improved atrial structure in a genetic model of atrial fibrosis. More recent studies revealed that D2 mice were remarkably resistant to heart failure induced by chronic elevated afterload as compared with their wild type (WT siblings), with a 6-fold increase in median survival as well as retention of relatively normal cardiac function. Finally, D2 mice exhibited a progressive recovery in cardiac function to normal levels and a concomitant reduction in adverse myocardial remodeling in an anthracycline cardiotoxicity model. Summary The studies reviewed here make a strong case for the potential utility of inducing cardiomyocyte renewal as a means to treat injured hearts. Several challenges which must be met to develop a viable therapeutic intervention based on these observations are discussed.
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    Targeted expression of cyclin D2 ameliorates late stage anthracycline cardiotoxicity
    (Oxford, 2018) Zhu, Wuqiang; Reuter, Sean; Field, Loren J.; Medicine, School of Medicine
    Aims Doxorubicin (DOX) is a widely used and effective anti-cancer therapeutic. DOX treatment is associated with both acute and late onset cardiotoxicity, limiting its overall efficacy. Here, the impact of cardiomyocyte cell cycle activation was examined in a juvenile model featuring aspects of acute and late onset DOX cardiotoxicity. Methods and results Two-week old MHC-cycD2 transgenic mice (which express cyclin D2 in postnatal cardiomyocytes and exhibit sustained cardiomyocyte cell cycle activity; D2 mice) and their wild type (WT) littermates received weekly DOX injections for 5 weeks (25 mg/kg cumulative dose). One week after the last DOX treatment (acute stage), cardiac function was suppressed in both groups. Acute DOX cardiotoxicity in D2 and WT mice was associated with similar increases in the levels of cardiomyocyte apoptosis and Ku70/Ku80 expression (markers of DNA damage and oxidative stress), as well as similar reductions in hypertrophic cardiomyocyte growth. Cardiac dysfunction persisted in WT mice for 13 weeks following the last DOX treatment (late stage) and was accompanied by increased levels of cardiomyocyte apoptosis, Ku expression, and myocardial fibrosis. In contrast, D2 mice exhibited a progressive recovery in cardiac function, which was indistinguishable from saline-treated animals by 9 weeks following the last DOX treatment. Improved cardiac function was accompanied by reductions in the levels of late stage cardiomyocyte apoptosis, Ku expression, and myocardial fibrosis. Conclusion These data suggest that cardiomyocyte cell cycle activity can promote recovery of cardiac function and preserve cardiac structure following DOX treatment.