Cardiomyocyte Regeneration in the mdx Mouse Model of Nonischemic Cardiomyopathy

• Published in: Stem cells and development Vol. 24; no. 14; pp. 1672 - 1679
• Main Authors: Richardson, Gavin David, Laval, Steven, Owens, William Andrew
• Format: Journal Article
• Language: English
• Published: United States Mary Ann Liebert, Inc 15.07.2015
• Subjects: Animals; Biological Transport; Bromodeoxyuridine - metabolism; Cardiomyopathies - therapy; Cell Nucleus - genetics; Cell Proliferation; Disease Models, Animal; DNA Replication - genetics; Flow Cytometry; Heart - growth & development; Mice; Mice, Inbred mdx; Myocardium - metabolism; Myocytes, Cardiac - physiology; Original Research Reports; Regeneration - physiology; Staining and Labeling
• ISSN: 1547-3287; 1557-8534
• DOI: 10.1089/scd.2014.0495

Endogenous regeneration has been demonstrated in the mammalian heart after ischemic injury. However, approximately one-third of cases of heart failure are secondary to nonischemic heart disease and cardiac regeneration in these cases remains relatively unexplored. We, therefore, aimed at quantifying the rate of new cardiomyocyte formation at different stages of nonischemic cardiomyopathy. Six-, 12-, 29-, and 44-week-old mdx mice received a 7 day pulse of BrdU. Quantification of isolated cardiomyocyte nuclei was undertaken using cytometric analysis to exclude nondiploid nuclei. Between 6–7 and 12–13 weeks, there was a statistically significant increase in the number of BrdU-labeled nuclei in the mdx hearts compared with wild-type controls. This difference was lost by the 29–30 week time point, and a significant decrease in cardiomyocyte generation was observed in both the control and mdx hearts by 44–45 weeks. Immunohistochemical analysis demonstrated BrdU-labeled nuclei exclusively in mononucleated cardiomyocytes. This study demonstrates cardiomyocyte regeneration in a nonischemic model of mammalian cardiomyopathy, controlling for changes in nuclear ploidy, which is lost with age, and confirms a decrease in baseline rates of cardiomyocyte regeneration with aging. While not attempting to address the cellular source of regeneration, it confirms the potential utility of innate regeneration as a therapeutic target.