Biomedicine

Healing the Heart

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Science  24 Aug 2001:
Vol. 293, Issue 5534, pp. 1403-1405
DOI: 10.1126/science.293.5534.1403e

The old adage “A wounded heart never heals” may not apply to frogs, but it accurately summarizes the biology of the mammalian heart. Although amphibians can regenerate functional heart muscle after injury, mammals respond to heart injury by forming nonfunctional scar tissue, possibly due to the inability of adult heart muscle cells, cardiomyocytes, in mammals to undergo division {although this idea has been challenged [Beltrami et al., N. Engl. J. Med. 344, 1750 (2001)]}.

Now, Leferovich et al. describe an animal model that may provide insight into the mechanisms that determine how the heart responds to injury. They show that MRL mice, a spontaneously arising mutant strain unusually proficient at healing surgical wounds, also have an extraordinary capacity to regenerate functional heart tissue after injury. A severe experimentally induced infarction across the wall of the right ventricle healed within 60 to 90 days in the MRL mice and was accompanied by cardiomyocyte DNA synthesis and revascularization of the wound site. In response to the same injury, control mice showed massive tissue scarring and no evidence of cardiomyocyte division. Because the wound healing response in the MRL mice is a heritable trait, future comparisons with mouse strains that cannot regenerate heart tissue may help to identify the molecules involved in the regenerative response and how the process is controlled. — PAK

Proc. Natl. Acad. Sci. U.S.A.98, 9830 (2001).

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