be230cLecture4

76 annually this level increased to 32 in the border

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Unformatted text preview: Turnover is not detectable in uninjured animals •  New cardiomyocytes do not come from pre ­exisAng cardiomyocytes •  Rather, new cardiomyocytes come from a stem or progenitor cell source •  Fish regeneraAon is robust and scarless •  New cardiomyocytes come from replicaAon of pre ­exisAng cardiomyocytes Neonatal Mice Regenerate Heart Muscle by ReplicaAon of ExisAng Cardiomyocytes Porrello, E.R. et al., Science 331: 1078 ­1080 (2011) 7 4/10/13 Evidence that Adult Myocardial RegeneraAon Occurs by ReplicaAon of Pre ­exisAng Cardiomyocytes •  •  •  •  15N pulse labeling of adult mouse hearts post ­myocardial infarcAon Use mass spectroscopy imaging to count nuclei that have 15N label, AND retain a GFP lineage label for pre ­ exisAng myocytes, AND are diploid (not polyploid) 6 cells out of 4190 analyzed fit this descripAon = basal rate of 0.76% annually. This level increased to 3.2% in the border region aRer myocardial infarcAon. Senyo et al., Nature 493(7432): 433 ­436 (2013). Heart RegeneraAon in Fish and Mammals Mouse Zebrafish •  Modest level of regeneraAon in the mouse heart aRer injury •  Turnover is not detectable in uninjured animals •  The source of new cardiomyocytes remains uncertain. They might arise from either replicaAon or from a stem cell populaAon. •  Neonatal mouse hearts regenerate efficiently. In neonatal mice, cardiomyocytes replicate and scarless regeneraAon occurs. •  Fish regeneraAon is robust and scarless •  New cardiomyocytes come from...
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