title: MicroRNA-mediated in vitro and in vivo direct reprogramming of cardiac fibroblasts to cardiomyocytes.
abstract: BACKGROUND
  Repopulation of the injured heart with new, functional cardiomyocytes remains a daunting challenge for cardiac regenerative medicine. An ideal therapeutic approach would involve an effective method at achieving direct conversion of injured areas to functional tissue in situ.
  
  
  OBJECTIVE
  The aim of this study was to develop a strategy that identified and evaluated the potential of specific micro (mi)RNAs capable of inducing reprogramming of cardiac fibroblasts directly to cardiomyocytes in vitro and in vivo.
  
  
  RESULTS
  Using a combinatorial strategy, we identified a combination of miRNAs 1, 133, 208, and 499 capable of inducing direct cellular reprogramming of fibroblasts to cardiomyocyte-like cells in vitro. Detailed studies of the reprogrammed cells demonstrated that a single transient transfection of the miRNAs can direct a switch in cell fate as documented by expression of mature cardiomyocyte markers, sarcomeric organization, and exhibition of spontaneous calcium flux characteristic of a cardiomyocyte-like phenotype. Interestingly, we also found that miRNA-mediated reprogramming was enhanced 10-fold on JAK inhibitor I treatment. Importantly, administration of miRNAs into ischemic mouse myocardium resulted in evidence of direct conversion of cardiac fibroblasts to cardiomyocytes in situ. Genetic tracing analysis using Fsp1Cre-traced fibroblasts from both cardiac and noncardiac cell sources strongly suggests that induced cells are most likely of fibroblastic origin.
  
  
  CONCLUSIONS
  The findings from this study provide proof-of-concept that miRNAs have the capability of directly converting fibroblasts to a cardiomyocyte-like phenotype in vitro. Also of significance is that this is the first report of direct cardiac reprogramming in vivo. Our approach may have broad and important implications for therapeutic tissue regeneration in general.
authors.affiliation: Duke Cardiovascular Research Center, Duke University Medical Center, Durham, NC 27710, USA.
authors.forename: Tilanthi M
authors.initials: TM
authors.lastname: Jayawardena
authors.forename: Bakytbek
authors.initials: B
authors.lastname: Egemnazarov
authors.forename: Elizabeth A
authors.initials: EA
authors.lastname: Finch
authors.forename: Lunan
authors.initials: L
authors.lastname: Zhang
authors.forename: J Alan
authors.initials: JA
authors.lastname: Payne
authors.forename: Kumar
authors.initials: K
authors.lastname: Pandya
authors.forename: Zhiping
authors.initials: Z
authors.lastname: Zhang
authors.forename: Paul
authors.initials: P
authors.lastname: Rosenberg
authors.forename: Maria
authors.initials: M
authors.lastname: Mirotsou
authors.forename: Victor J
authors.initials: VJ
authors.lastname: Dzau
mesh_terms: D000818:Animals; D054338:Cell Transdifferentiation / Q000187:drug effects / Q000235:genetics; D002478:Cells, Cultured; D004195:Disease Models, Animal; D005347:Fibroblasts / Q000187:drug effects / Q000378:metabolism* / Q000473:pathology; D005786:Gene Expression Regulation; D015316:Genetic Therapy / Q000379:methods; D053613:Janus Kinase 1 / Q000037:antagonists & inhibitors / Q000378:metabolism; D008164:Luminescent Proteins / Q000235:genetics / Q000378:metabolism; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D008822:Mice, Transgenic; D035683:MicroRNAs / Q000008:administration & dosage / Q000378:metabolism*; D009200:Myocardial Contraction; D017202:Myocardial Ischemia / Q000235:genetics / Q000378:metabolism / Q000473:pathology / Q000503:physiopathology / Q000628:therapy; D032383:Myocytes, Cardiac / Q000187:drug effects / Q000378:metabolism* / Q000473:pathology; D047428:Protein Kinase Inhibitors / Q000494:pharmacology; D020127:Recovery of Function; D012038:Regeneration; D009418:S100 Proteins / Q000235:genetics / Q000378:metabolism; D014162:Transfection; D000097573:Red Fluorescent Protein
chemical_list: D053613:Janus Kinase 1; D008164:Luminescent Proteins; D035683:MicroRNAs; D047428:Protein Kinase Inhibitors; D009418:S100 Proteins; D000097573:Red Fluorescent Protein; C507905:Jak1 protein, mouse