title: Dynamic tracking during intracoronary injection of 18F-FDG-labeled progenitor cell therapy for acute myocardial infarction.
abstract: We assessed the feasibility of dynamic 3-dimensional (3D) PET/CT tracking of (18)F-FDG-labeled circulating progenitor cell (CPC) therapy during intracoronary injection, using a porcine model of acute myocardial infarction (MI).
  
  
  METHODS
  Human and porcine CPC were radiolabeled with (18)F-FDG, with variation in temperature and incubation time to determine optimal conditions. For in vivo experiments, CPC were harvested before induction of infarction (using 90-min coronary balloon occlusion). At 48 h, animals underwent cardiac MRI to assess infarct size. A balloon catheter was placed in the infarct artery at the same location as that used for induction of MI, and during dynamic 3D PET/CT 3 x 10(7) autologous (18)F-FDG progenitor cells were injected through the central lumen using either (a) 3 cycles of balloon occlusion and reperfusion or (b) high-concentration, single-bolus injection without balloon occlusion (n = 3 for both protocols). Peripheral blood was drawn at 1-min intervals during cell injection.
  
  
  RESULTS
  Labeling efficiency was optimized by 30-min incubation at 37 degrees C (human CPC, 89.9% +/- 4.8%; porcine CPC, 91.6% +/- 6.4%). Cell-bound activity showed a nonsignificant decrease at 1 h (human, 74.3% +/- 10.7%; porcine, 77.7% +/- 12.8%; P > 0.05) and a significant decrease at 2 h (human, 62.1% +/- 8.9%; porcine, 68.6% +/- 5.4%; P = 0.009). Mean infarct size was similar for both injection protocols (16.3% +/- 3.4% and 20.6% +/- 2.7%; P > 0.05). Dynamic scanning demonstrated a sharp rise in myocardial activity during each cycle of balloon-occlusion cell delivery, with a significant fall in activity (around 80%) immediately after balloon deflation. The latter was associated with a transient spike in peripheral blood (18)F-FDG activity, consistent with the first pass of labeled cells in the systemic circulation. A single spike and gradual fall in myocardial activity was observed with high-concentration, single-bolus therapy. At 1 h, myocardial activity was 8.7% +/- 1.5% of total injected dose for balloon-occlusion delivery and 17.8% +/- 7.9% for high-concentration, single-bolus delivery (P = 0.08).
  
  
  CONCLUSIONS
  Dynamic tracking during intracoronary injection of (18)F-FDG-labeled CPC is feasible and demonstrates significant cell washout from the myocardium immediately after balloon deflation. High-concentration, single-bolus therapy may be as effective as balloon-occlusion delivery. This tracking technique should facilitate development of improved delivery strategies for cardiac cell therapy.
authors.affiliation: Molecular Medicine Program, Mayo Clinic College of Medicine, Rochester, Minnesota, USA.
authors.forename: Brendan
authors.initials: B
authors.lastname: Doyle
authors.forename: Brad J
authors.initials: BJ
authors.lastname: Kemp
authors.forename: Panithaya
authors.initials: P
authors.lastname: Chareonthaitawee
authors.forename: Cynthia
authors.initials: C
authors.lastname: Reed
authors.forename: Jeffrey
authors.initials: J
authors.lastname: Schmeckpeper
authors.forename: Paul
authors.initials: P
authors.lastname: Sorajja
authors.forename: Stephen
authors.initials: S
authors.lastname: Russell
authors.forename: Philip
authors.initials: P
authors.lastname: Araoz
authors.forename: Stephen J
authors.initials: SJ
authors.lastname: Riederer
authors.forename: Noel M
authors.initials: NM
authors.lastname: Caplice
mesh_terms: D000818:Animals; D002452:Cell Count / Q000379:methods*; D002478:Cells, Cultured; D005240:Feasibility Studies; D019788:Fluorodeoxyglucose F18; D006801:Humans; D007267:Injections; D009203:Myocardial Infarction / Q000000981:diagnostic imaging* / Q000601:surgery*; D049268:Positron-Emission Tomography / Q000379:methods; D019275:Radiopharmaceuticals; D033581:Stem Cell Transplantation / Q000379:methods*; D013234:Stem Cells / Q000000981:diagnostic imaging*; D013552:Swine
chemical_list: D019275:Radiopharmaceuticals; D019788:Fluorodeoxyglucose F18