title: c-kit expression identifies cardiovascular precursors in the neonatal heart.
abstract: Directed differentiation of embryonic stem cells indicates that mesodermal lineages in the mammalian heart (cardiac, endothelial, and smooth muscle cells) develop from a common, multipotent cardiovascular precursor. To isolate and characterize the lineage potential of a resident pool of cardiovascular progenitor cells (CPcs), we developed BAC transgenic mice in which enhanced green fluorescent protein (EGFP) is placed under control of the c-kit locus (c-kit(BAC)-EGFP mice). Discrete c-kit-EGFP(+) cells were observed at different stages of differentiation in embryonic hearts, increasing in number to a maximum at about postnatal day (PN) 2; thereafter, EGFP(+) cells declined and were rarely observed in the adult heart. EGFP(+) cells purified from PN 0-5 hearts were nestin(+) and expanded in culture; 67% of cells were fluorescent after 9 days. Purified cells differentiated into endothelial, cardiac, and smooth muscle cells, and differentiation could be directed by specific growth factors. CPc-derived cardiac myocytes displayed rhythmic beating and action potentials characteristic of multiple cardiac cell types, similar to ES cell-derived cardiomyocytes. Single-cell dilution studies confirmed the potential of individual CPcs to form all 3 cardiovascular lineages. In adult hearts, cryoablation resulted in c-kit-EGFP(+) expression, peaking 7 days postcryolesion. Expression occurred in endothelial and smooth muscle cells in the revascularizing infarct, and in terminally differentiated cardiomyocytes in the border zone surrounding the infarct. Thus, c-kit expression marks CPc in the neonatal heart that are capable of directed differentiation in vitro; however, c-kit expression in cardiomyocytes in the adult heart after injury does not identify cardiac myogenesis.
authors.affiliation: Biomedical Sciences Department, College of Veterinary Medicine, Cornell University, Ithaca, NY 14853, USA.
authors.forename: Yvonne N
authors.initials: YN
authors.lastname: Tallini
authors.forename: Kai Su
authors.initials: KS
authors.lastname: Greene
authors.forename: Michael
authors.initials: M
authors.lastname: Craven
authors.forename: Alyson
authors.initials: A
authors.lastname: Spealman
authors.forename: Martin
authors.initials: M
authors.lastname: Breitbach
authors.forename: James
authors.initials: J
authors.lastname: Smith
authors.forename: Patricia J
authors.initials: PJ
authors.lastname: Fisher
authors.forename: Michele
authors.initials: M
authors.lastname: Steffey
authors.forename: Michael
authors.initials: M
authors.lastname: Hesse
authors.forename: Robert M
authors.initials: RM
authors.lastname: Doran
authors.forename: Ashley
authors.initials: A
authors.lastname: Woods
authors.forename: Babu
authors.initials: B
authors.lastname: Singh
authors.forename: Andrew
authors.initials: A
authors.lastname: Yen
authors.forename: Bernd K
authors.initials: BK
authors.lastname: Fleischmann
authors.forename: Michael I
authors.initials: MI
authors.lastname: Kotlikoff
mesh_terms: D000818:Animals; D000831:Animals, Newborn; D002319:Cardiovascular System / Q000166:cytology; D002454:Cell Differentiation; D019070:Cell Lineage; D003331:Coronary Vessels / Q000166:cytology; D003452:Cryosurgery; D004622:Embryo, Mammalian; D049452:Green Fluorescent Proteins / Q000235:genetics; D008648:Mesoderm / Q000166:cytology; D051379:Mice; D008815:Mice, Inbred Strains; D008822:Mice, Transgenic; D039902:Multipotent Stem Cells / Q000166:cytology*; D009206:Myocardium / Q000166:cytology*; D032383:Myocytes, Cardiac / Q000166:cytology; D019009:Proto-Oncogene Proteins c-kit / Q000032:analysis*
chemical_list: D049452:Green Fluorescent Proteins; D019009:Proto-Oncogene Proteins c-kit