title: Enhanced angiogenic and cardiomyocyte differentiation capacity of epigenetically reprogrammed mouse and human endothelial progenitor cells augments their efficacy for ischemic myocardial repair.
abstract: BACKGROUND
  Although bone marrow endothelial progenitor cell (EPC)-based therapies improve the symptoms in patients with ischemic heart disease, their limited plasticity and decreased function in patients with existing heart disease limit the full benefit of EPC therapy for cardiac regenerative medicine.
  
  
  OBJECTIVE
  We hypothesized that reprogramming mouse or human EPCs, or both, using small molecules targeting key epigenetic repressive marks would lead to a global increase in active gene transcription, induce their cardiomyogenic potential, and enhance their inherent angiogenic potential.
  
  
  RESULTS
  Mouse Lin-Sca1(+)CD31(+) EPCs and human CD34(+) cells were treated with inhibitors of DNA methyltransferases (5-Azacytidine), histone deacetylases (valproic acid), and G9a histone dimethyltransferase. A 48-hour treatment led to global increase in active transcriptome, including the reactivation of pluripotency-associated and cardiomyocyte-specific mRNA expression, whereas endothelial cell-specific genes were significantly upregulated. When cultured under appropriate differentiation conditions, reprogrammed EPCs showed efficient differentiation into cardiomyocytes. Treatment with epigenetic-modifying agents show marked increase in histone acetylation on cardiomyocyte and pluripotent cell-specific gene promoters. Intramyocardial transplantation of reprogrammed mouse and human EPCs in an acute myocardial infarction mouse model showed significant improvement in ventricular functions, which was histologically supported by their de novo cardiomyocyte differentiation and increased capillary density and reduced fibrosis. Importantly, cell transplantation was safe and did not form teratomas.
  
  
  CONCLUSIONS
  Taken together, our results suggest that epigenetically reprogrammed EPCs display a safe, more plastic phenotype and improve postinfarct cardiac repair by both neocardiomyogenesis and neovascularization.
authors.affiliation: Feinberg Cardiovascular Research Institute, Feinberg School of Medicine, Northwestern University, Chicago IL 60611, USA.
authors.forename: Melissa A
authors.initials: MA
authors.lastname: Thal
authors.forename: Prasanna
authors.initials: P
authors.lastname: Krishnamurthy
authors.forename: Alexander R
authors.initials: AR
authors.lastname: Mackie
authors.forename: Eneda
authors.initials: E
authors.lastname: Hoxha
authors.forename: Erin
authors.initials: E
authors.lastname: Lambers
authors.forename: Suresh
authors.initials: S
authors.lastname: Verma
authors.forename: Veronica
authors.initials: V
authors.lastname: Ramirez
authors.forename: Gangjian
authors.initials: G
authors.lastname: Qin
authors.forename: Douglas W
authors.initials: DW
authors.lastname: Losordo
authors.forename: Raj
authors.initials: R
authors.lastname: Kishore
mesh_terms: D000818:Animals; D002454:Cell Differentiation / Q000235:genetics*; D002478:Cells, Cultured; D042783:Endothelial Cells / Q000473:pathology / Q000502:physiology* / Q000637:transplantation; D004730:Endothelium, Vascular / Q000473:pathology / Q000502:physiology / Q000637:transplantation; D044127:Epigenesis, Genetic / Q000235:genetics*; D006801:Humans; D051379:Mice; D008810:Mice, Inbred C57BL; D008822:Mice, Transgenic; D017202:Myocardial Ischemia / Q000235:genetics* / Q000473:pathology / Q000601:surgery; D032383:Myocytes, Cardiac / Q000473:pathology / Q000502:physiology*; D018919:Neovascularization, Physiologic / Q000235:genetics; D033581:Stem Cell Transplantation / Q000379:methods*; D013234:Stem Cells / Q000473:pathology / Q000502:physiology; D016896:Treatment Outcome; D015854:Up-Regulation / Q000235:genetics*