title: Plasma miR-208 as a biomarker of myocardial injury.
abstract: BACKGROUND
  MicroRNAs (miRNAs) are endogenous small RNAs of 21-25 nucleotides that can pair with sites in 3' untranslated regions in mRNAs of protein-coding genes to downregulate their expression. Recently, circulating miRNAs have been reported as promising biomarkers for various pathologic conditions. We assessed the hypothesis that miRNAs may leak into the circulating blood from injured cells and thereby serve as biomarkers for identifying the injured cell type.
  
  
  METHODS
  We used isoproterenol-induced myocardial injury in rats as a model and miRNA array analyses to identify candidate miRNAs specifically produced in the ventricles of the heart. Individual miRNA concentrations were measured by real-time reverse-transcription PCR. Plasma cardiac troponin I (cTnI) concentrations were measured with an ELISA.
  
  
  RESULTS
  Array analyses revealed miR-208 to be produced exclusively in the heart, and we selected this miRNA as a possible biomarker of myocardial injury. Plasma concentrations of miR-208 increased significantly (P < 0.0001) after isoproterenol-induced myocardial injury and showed a similar time course to the concentration of cTnI, a classic biomarker of myocardial injury.
  
  
  CONCLUSIONS
  The plasma concentration of miR-208 may be a useful indicator of myocardial injury. Our results suggest that profiling of circulating miRNAs may help identify promising biomarkers of various pathologic conditions.
authors.affiliation: Department of Epidemiology, Research Institute, National Cardiovascular Center, Osaka 565-8565, Japan.
authors.forename: Xu
authors.initials: X
authors.lastname: Ji
authors.forename: Rie
authors.initials: R
authors.lastname: Takahashi
authors.forename: Yumiko
authors.initials: Y
authors.lastname: Hiura
authors.forename: Go
authors.initials: G
authors.lastname: Hirokawa
authors.forename: Yasue
authors.initials: Y
authors.lastname: Fukushima
authors.forename: Naoharu
authors.initials: N
authors.lastname: Iwai
mesh_terms: D000818:Animals; D001219:Aspartate Aminotransferases / Q000097:blood; D006332:Cardiomegaly / Q000235:genetics; D006335:Heart Injuries / Q000139:chemically induced / Q000175:diagnosis*; D007545:Isoproterenol; D007668:Kidney / Q000098:blood supply / Q000473:pathology; D008297:Male; D035683:MicroRNAs / Q000032:analysis* / Q000097:blood; D009206:Myocardium / Q000378:metabolism / Q000473:pathology*; D051381:Rats; D017207:Rats, Sprague-Dawley; D020133:Reverse Transcriptase Polymerase Chain Reaction
chemical_list: D035683:MicroRNAs; D001219:Aspartate Aminotransferases; D007545:Isoproterenol