be230cLecture4

In injured hearts results were even more variable

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Unformatted text preview:   Controversial evidence in the 1970s to 1990s regarding whether or not new cardiomyocytes arise in healthy or injured hearts. This reinforced the noAon that cardiomyocytes are forever post ­mitoAc. •  In normal adult rats and mice, the percentage of cardiomyocytes that were synthesizing DNA is reported to range from 0.005% ­3.15% and 0.0004% ­0.04%, respecAvely (Soonpaa and Field, 1998). •  In injured hearts, results were even more variable, ranging from 0.0006% ­43.6% in rats and 0.0055% ­0.5% in mice (Soonpaa and Field, 1998). Soonpaa, M.H. and Field, L.J. 1998. Circula5on research 83(1): 15 ­26. 4 4/10/13 Evidence for Heart RegeneraAon in Adult Mice Beltrami, A.P. et al., Cell 114(6): 763 ­776 (2003). Kajstura, J., et al., Circula5on research 107(2): 305 ­315 (2010). IdU IncorporaAon in Humans •  Myocyte labelling with IdU = 2.5% to 46% formed over an average of 406 days. •  Phospho ­Histone 3+ cells are 70/10^6 cardiomyocytes. •  These values lead to an esAmated 8 year half ­life for a cardiomyocyte, equalling mulAple cycles over a lifeAme. •  Why such high levels? Mistaking DNA repair for replicaAon? Mistaking non ­ cardiomyocytes for cardiomyocytes? Kajstura J et al. Circulation Research 2010;107:305-315 Glo...
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