Adult stem cell therapy is expected to improve left ventricular function in patients with myocardial infarction. Because of the low risk of arrhythmia and the maximal concentration at the target tissue, intracoronary infusion of stem cells is preferred. The aim of this study was to investigate the homing and tissue distribution of intracoronary injected peripheral hematopoietic stem cells labeled with 18F-FDG.
Methods: Seventeen patients with myocardial infarction were included as the intracoronary injection group (14 males, 3 females; age, 58 +/- 12 y). Three patients underwent intravenous stem cell injection as the intravenous injection group (3 males, 0 females; age, 50 +/- 20 y). After mobilization with granulocyte colony-stimulating factor (G-CSF), peripheral stem cells were collected by means of apheresis. 18F-FDG labeling of stem cells was performed for 40 min with gentle intermittent mixing at 37 degrees C. The mean labeling efficiency was 72% (range, 46%-95%), and 44.4-175 MBq (1.2-5 mCi) of 18F-FDG-labeled stem cells were injected via an intracoronary catheter after stenting in infarct-related arteries. PET/CT images were obtained with a 3-dimensional acquisition mode 2 h after intracoronary infusion.
Results: Two hours after intracoronary infusion, 1.5% (range, 0.2%-3.3%) of injected stem cells accumulated at the infarcted myocardium. Outside of the myocardium, spleen, liver, bladder, and bone marrow showed a high stem cell accumulation. The delayed image of a patient up to 20 h showed a prolonged residence of stem cells at the myocardium. Intravenous injection of stem cells showed a high initial lung uptake with no myocardial activity.
Conclusion: We have shown that 18F-FDG-labeled stem cell PET could be used to assess the tissue distribution and to measure the amount of stem cells at a target tissue. 18F-FDG-labeled stem cell PET can be used to measure and optimize the amount of stem cells injected.