title: c-MYC independent nuclear reprogramming favors cardiogenic potential of induced pluripotent stem cells.
abstract: Induced pluripotent stem cell (iPS) technology has launched a new platform in regenerative medicine aimed at deriving unlimited replacement tissue from autologous sources through somatic cell reprogramming using stemness factor sets. In this way, authentic cardiomyocytes have been obtained from iPS and recently demonstrated in proof-of-principle studies to repair infarcted heart. Optimizing the cardiogenic potential of iPS progeny would ensure a maximized yield of bioengineered cardiac tissue. Here, we reprogrammed fibroblasts in the presence or absence of c-MYC to determine if the acquired cardiogenicity is sensitive to the method of nuclear reprogramming. Using lentiviral constructs that expressed stemness factors SOX2, OCT4, and KLF4 with or without c-MYC, iPS clones generated through fibroblast reprogramming demonstrated indistinguishable characteristics for 5 days of differentiation with similar cell morphology, growth rates, and chimeric embryo integration. However, 4-factor c-MYC dependent nuclear reprogramming produced iPS progeny that consistently prolonged the expression of pluripotent Oct-4 and Fgf4 genes and repressed cardiac differentiation. In contrast, 3-factor c-MYC-less iPS clones efficiently up-regulated pre-cardiac (CXCR4, Flk-1, and Mesp1/2) and cardiac (Nkx2.5, Mef2c, and Myocardin) gene expression patterns. In fact, 3-factor iPS progeny demonstrated early and robust cardiogenesis during in vitro differentiation with consistent beating activity, sarcomere maturation, and rhythmical intracellular calcium dynamics. Thus, nuclear reprogramming independent of c-MYC enhances production of pluripotent stem cells with innate cardiogenic potential.
authors.affiliation: Division of Cardiovascular Diseases, Departments of Medicine, Mayo Clinic, Rochester, MN, USA.
authors.forename: Almudena
authors.initials: A
authors.lastname: Martinez-Fernandez
authors.forename: Timothy J
authors.initials: TJ
authors.lastname: Nelson
authors.forename: Yasuhiro
authors.initials: Y
authors.lastname: Ikeda
authors.forename: Andre
authors.initials: A
authors.lastname: Terzic
mesh_terms: D000818:Animals; D002454:Cell Differentiation / Q000235:genetics; D019070:Cell Lineage / Q000235:genetics; D002478:Cells, Cultured; D065150:Cellular Reprogramming; D046149:Embryo Culture Techniques; D005347:Fibroblasts / Q000378:metabolism*; D018507:Gene Expression Regulation, Developmental; D006801:Humans; D057026:Induced Pluripotent Stem Cells / Q000378:metabolism*; D000090062:Kruppel-Like Factor 4; D051741:Kruppel-Like Transcription Factors / Q000235:genetics / Q000378:metabolism; D051379:Mice; D032383:Myocytes, Cardiac / Q000378:metabolism*; D050814:Octamer Transcription Factor-3 / Q000235:genetics / Q000378:metabolism; D016271:Proto-Oncogene Proteins c-myc / Q000235:genetics / Q000378:metabolism*; D055748:SOXB1 Transcription Factors / Q000235:genetics / Q000378:metabolism; D013997:Time Factors; D014161:Transduction, Genetic
chemical_list: C000715467:KLF4 protein, human; C000715468:Klf4 protein, mouse; D000090062:Kruppel-Like Factor 4; D051741:Kruppel-Like Transcription Factors; C489427:MYC protein, human; D050814:Octamer Transcription Factor-3; C494173:POU5F1 protein, human; D016271:Proto-Oncogene Proteins c-myc; C527782:SOX2 protein, human; D055748:SOXB1 Transcription Factors