title: Assessment of three techniques for delivering stem cells to the heart using PET and MR imaging.
abstract: BACKGROUND
  Stem cell therapy has a promising potential for the curing of various degenerative diseases, including congestive heart failure (CHF). In this study, we determined the efficacy of different delivery methods for stem cell administration to the heart for the treatment of CHF. Both positron emission tomography (PET) and magnetic resonance imaging (MRI) were utilized to assess the distribution of delivered stem cells.
  
  
  METHODS
  Adipose-derived stem cells of male rats were labeled with super-paramagnetic iron oxide (SPIO) and 18 F-fluorodeoxyglucose (FDG). The left anterior descending coronary artery (LAD) of the female rats was occluded to induce acute ischemic myocardial injury. Immediately after the LAD occlusion, the double-labeled stem cells were injected into the ischemic myocardium (n = 5), left ventricle (n = 5), or tail vein (n = 4). In another group of animals (n = 3), the stem cells were injected directly into the infarct rim 1 week after the LAD occlusion. Whole-body PET images and MR images were acquired to determine biodistribution of the stem cells. After the imaging, the animals were euthanized and retention of the stem cells in the vital organs was determined by measuring the cDNA specific to the Y chromosome.
  
  
  RESULTS
  PET images showed that retention of the stem cells in the ischemic myocardium was dependent on the cell delivery method. The tail vein injection resulted in the least cell retention in the heart (1.2% ± 0.6% of total injected cells). Left ventricle injection led to 3.5% ± 0.9% cell retention and direct myocardial injection resulted in the highest rate of cell retention (14% ± 4%) in the heart. In the animals treated 1 week after the LAD occlusion, rate of cell retention in the heart was only 4.5% ±1.1%, suggesting that tissue injury has a negative impact on cell homing. In addition, there was a good agreement between the results obtained through PET-MR imaging and histochemical measurements.
  
  
  CONCLUSIONS
  PET-MR imaging is a reliable technique for noninvasive tracking of implanted stem cells in vivo. Direct injection of stem cells into the myocardium is the most effective way for cell transplantation to the heart in heart failure models.
authors.affiliation: Department of Physics, University of Winnipeg, 515 Portage Avenue, Winnipeg MB R3B 2E9, Canada. e.elhami@uwinnipeg.ca.
authors.forename: Esmat
authors.initials: E
authors.lastname: Elhami
authors.forename: Bryson
authors.initials: B
authors.lastname: Dietz
authors.forename: Bo
authors.initials: B
authors.lastname: Xiang
authors.forename: Jixian
authors.initials: J
authors.lastname: Deng
authors.forename: Fei
authors.initials: F
authors.lastname: Wang
authors.forename: Chao
authors.initials: C
authors.lastname: Chi
authors.forename: Andrew L
authors.initials: AL
authors.lastname: Goertzen
authors.forename: Shadreck
authors.initials: S
authors.lastname: Mzengeza
authors.forename: Darren
authors.initials: D
authors.lastname: Freed
authors.forename: Rakesh C
authors.initials: RC
authors.lastname: Arora
authors.forename: Ganghong
authors.initials: G
authors.lastname: Tian