title: Exosomes secreted from GATA-4 overexpressing mesenchymal stem cells serve as a reservoir of anti-apoptotic microRNAs for cardioprotection.
abstract: BACKGROUND
  Exosomes play an important role in intercellular signaling and exert regulatory function by carrying bioactive molecules. This study investigated (1) the cardioprotective capabilities of exosomes derived from mesenchymal stem cells (MSCs) overexpressing GATA-4 (MSC(GATA-4)) and (2) its underlying regulatory mechanisms for expression of target proteins in recipient cells.
  
  
  RESULTS
  Exosomes were isolated and purified from MSC(GATA-4) (Exo(GATA-4)) and control MSCs (Exo(Null)). Cell injury was investigated in primary cultured rat neonatal cardiomyocytes (CM) and in the rat heart. Exosomes contributed to increased CM survival, reduced CM apoptosis, and preserved mitochondrial membrane potential in CM cultured under a hypoxic environment. Direct intramyocardial transplantation of exosomes at the border of an ischemic region following ligation of the left anterior descending coronary artery significantly restored cardiac contractile function and reduced infarct size. Real-time PCR revealed that several anti-apoptotic miRs were highly expressed in Exo(GATA-4). Rapid internalization of Exo(GATA-4) by CM was documented using time-lapse imaging. Subsequent expression of these miRs, particularly miR-19a was higher in CM and in the myocardium treated with Exo(GATA-4) compared to those treated with Exo(Null). The enhanced protective effects observed in CM were diminished by the inhibition of miR-19a. The expression level of PTEN, a predicted target of miR-19a, was reduced in CM treated with Exo(GATA-4), which resulted in the activation of the Akt and ERK signaling pathways.
  
  
  CONCLUSIONS
  Exo(GATA-4) upon transplantation in the damaged tissue mediate protection by releasing multiple miRs responsible for activation of the cell survival signaling pathway.
authors.affiliation: Department of Pathology and Laboratory Medicine, University of Cincinnati Medical Center, Cincinnati, OH 45267, USA.
authors.forename: Bin
authors.initials: B
authors.lastname: Yu
authors.affiliation: Department of Pathology and Laboratory Medicine, University of Cincinnati Medical Center, Cincinnati, OH 45267, USA.
authors.forename: Ha Won
authors.initials: HW
authors.lastname: Kim
authors.affiliation: Department of Pathology and Laboratory Medicine, University of Cincinnati Medical Center, Cincinnati, OH 45267, USA.
authors.forename: Min
authors.initials: M
authors.lastname: Gong
authors.affiliation: Department of Pathology and Laboratory Medicine, University of Cincinnati Medical Center, Cincinnati, OH 45267, USA.
authors.forename: Jingcai
authors.initials: J
authors.lastname: Wang
authors.affiliation: Department of Pharmacology & Cell Biophysics, University of Cincinnati Medical Center, Cincinnati, OH 45267, USA.
authors.forename: Ronald W
authors.initials: RW
authors.lastname: Millard
authors.affiliation: Department of Pathology and Laboratory Medicine, University of Cincinnati Medical Center, Cincinnati, OH 45267, USA.
authors.forename: Yigang
authors.initials: Y
authors.lastname: Wang
authors.affiliation: Department of Pathology and Laboratory Medicine, University of Cincinnati Medical Center, Cincinnati, OH 45267, USA.
authors.forename: Muhammad
authors.initials: M
authors.lastname: Ashraf
authors.affiliation: Department of Pathology and Laboratory Medicine, University of Cincinnati Medical Center, Cincinnati, OH 45267, USA. Electronic address: Meifeng.xu@uc.edu.
authors.forename: Meifeng
authors.initials: M
authors.lastname: Xu
mesh_terms: D000818:Animals; D017209:Apoptosis; D002470:Cell Survival; D002478:Cells, Cultured; D055354:Exosomes; D050991:GATA4 Transcription Factor / Q000096:biosynthesis / Q000235:genetics*; D005786:Gene Expression Regulation; D045164:Mesenchymal Stem Cell Transplantation / Q000379:methods*; D059630:Mesenchymal Stem Cells / Q000166:cytology / Q000378:metabolism*; D035683:MicroRNAs / Q000378:metabolism*; D009203:Myocardial Infarction / Q000235:genetics* / Q000378:metabolism / Q000628:therapy; D032383:Myocytes, Cardiac / Q000378:metabolism / Q000473:pathology; D012313:RNA / Q000235:genetics; D051381:Rats; D060888:Real-Time Polymerase Chain Reaction
chemical_list: D050991:GATA4 Transcription Factor; D035683:MicroRNAs; D012313:RNA
keywords: Bone marrow stem cells; Cardioprotection; Exosomes; GATA-4; MiR transfer; Target proteins