title: In vivo magnetic resonance imaging of injected endothelial progenitor cells after myocardial infarction in rats.
abstract: OBJECTIVE
  The purpose of this study was to detect and follow transplanted superparamagnetic iron oxide (SPIO)-labeled endothelial progenitor cells (EPCs) by magnetic resonance imaging (MRI).
  
  
  METHODS
  Infarcted rats were randomized to injections of SPIO-labeled EPCs, unlabeled EPCs, or saline. From 1 day to 8 weeks, in vivo serial MRI was performed for cell tracking.
  
  
  RESULTS
  Labeled cells were visualized as hypointense areas by MRI. The presence of labeled EPCs at 10 days and disappearance of these cells by 8 weeks was confirmed by iron and 4',6-diamidino-2-phenylindole. Co-staining for iron and ED-1 showed that the iron-positive cells were macrophages. EPC implantation significantly elevated vascular endothelial growth factor expression, accompanied by increased capillary and arteriole density in the ischemic myocardium.
  
  
  CONCLUSIONS
  At 8 weeks, the transplanted EPCs were not present and the enhanced MRI signals arose from macrophages. However, both EPCs enhanced cardiac function. The major mechanism of cardiac improvement appears to be paracrine pathways of the engrafted EPCs.
authors.affiliation: Department of Cardiology, Zhongda Hospital, Southeast University, 87 Dingjiaqiao, Nanjing, Jiangsu, 210009, China.
authors.forename: Yuyu
authors.initials: Y
authors.lastname: Yao
authors.forename: Yefei
authors.initials: Y
authors.lastname: Li
authors.forename: Genshan
authors.initials: G
authors.lastname: Ma
authors.forename: Naifeng
authors.initials: N
authors.lastname: Liu
authors.forename: Shenghong
authors.initials: S
authors.lastname: Ju
authors.forename: Jiyang
authors.initials: J
authors.lastname: Jin
authors.forename: Zhong
authors.initials: Z
authors.lastname: Chen
authors.forename: Chengxing
authors.initials: C
authors.lastname: Shen
authors.forename: Gaojun
authors.initials: G
authors.lastname: Teng
mesh_terms: D000818:Animals; D017209:Apoptosis; D001854:Bone Marrow Cells / Q000166:cytology; D002478:Cells, Cultured; D003287:Contrast Media; D042783:Endothelial Cells / Q000166:cytology* / Q000637:transplantation*; D052203:Ferrosoferric Oxide / Q000378:metabolism; D006334:Heart Function Tests; D007249:Inflammation / Q000150:complications / Q000473:pathology; D007267:Injections; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D009203:Myocardial Infarction / Q000150:complications / Q000473:pathology / Q000503:physiopathology / Q000628:therapy*; D018919:Neovascularization, Physiologic; D051381:Rats; D017207:Rats, Sprague-Dawley; D013194:Staining and Labeling; D033581:Stem Cell Transplantation; D013234:Stem Cells / Q000166:cytology*
chemical_list: D003287:Contrast Media; D052203:Ferrosoferric Oxide