title: Thymosin β4 and cardiac regeneration: are we missing a beat?
abstract: Epicardial resident stem cells are known to differentiate into cardiomyocytes during cardiac development, amongst other cell types. Whether epicardium-derived progenitor cells (EPDCs) retain this plasticity in the adult heart has been the topic of heated scientific debate. Priming with thymosin beta 4, a peptide which has been suggested to be critical for cardiac development and to have cardio-protective properties, was recently shown to induce differentiation of EPDCs into cardiomyocytes in a small animal model of myocardial infarction. This finding is in stark contrast to another recent study in which thymosin beta 4 treatment following myocardial infarction did not induce cardiomyocyte differentiation of EPDCs. While EPDCs seem to exhibit overall cardio-protective effects on the heart following myocardial infarction, they have not been shown to differentiate into cardiomyocytes in a clinically relevant setting. It will be important to understand why the ability of one therapeutic agent to induce cardiomyocyte differentiation of EPDCs seemingly depends on a single variable, i.e. the time of administration. Furthermore, in light of a recent report, it appears that thymosin beta 4 may be dispensable for cardiac development.
authors.affiliation: Cardiovascular Regenerative Medicine, Cardiovascular Research Center, Mount Sinai School of Medicine, One Gustave L. Levy Place, Box 1030, New York, NY 10029, USA. david.gajzer@mssm.edu
authors.forename: David C
authors.initials: DC
authors.lastname: Gajzer
authors.forename: Jerome
authors.initials: J
authors.lastname: Balbin
authors.forename: Hina W
authors.initials: HW
authors.lastname: Chaudhry
mesh_terms: D002454:Cell Differentiation / Q000187:drug effects*; D006321:Heart; D006801:Humans; D009203:Myocardial Infarction / Q000628:therapy*; D009206:Myocardium / Q000166:cytology / Q000378:metabolism; D032383:Myocytes, Cardiac / Q000378:metabolism; D012038:Regeneration / Q000187:drug effects*; D033581:Stem Cell Transplantation; D013234:Stem Cells / Q000187:drug effects / Q000378:metabolism; D013947:Thymosin / Q000494:pharmacology*; D000099201:Thymosin beta(4)
chemical_list: D013947:Thymosin; D000099201:Thymosin beta(4)