Abstract 18167: Improved Stem Cell Tracking after Intramyocardial Injection by Hexadecyl-4-[18F]fluorobenzoate Labeling with Positron Emission Tomography
Background: To assess the fate of transplanted stem cells, hexadecyl–41–[18F]fluorobenzoate (18F-HFB) cell labeling was used to track intramyocardially delivered human circulating progenitor cells (hCPCs) by PET, and was compared to 18F-FDG labeling.
Methods: hCPCs were labeled with 18F-HFB or 18F-FDG under the same conditions. Two weeks after left coronary artery ligation, rats received echo-guided intramyocardial injection in the infarct border zone with one of the following: 18F-HFB-labeled hCPCs; 18F-FDG-labeled hCPCs; 18F-HFB; or 18F-FDG (n=5/group). PET images were acquired to assess the homing of transplanted hCPCs at 10min, 2h, and 4h post-injection. Animals were subsequently sacrificed, and tissues harvested for biodistribution and immunofluorescence studies.
Results: 18F-HFB cell labeling efficiency (27.3±6.9%) and stability (4h, 87.9±4.8%) were much better than 18F-FDG (5.8±3.1% and 40.2±6.6%, respectively; p<0.05). Neither labeling approach significantly altered cell viability, phenotype or migratory potential 24h post-labeling. Dynamic PET imaging of both 18F-HFB-CPCs and 18F-FDG-CPCs demonstrated that only 25–59% injection dose (ID) was retained in the injection site at 10min post-delivery, and that remaining activity fell significantly over the first 4h post-injection. The 18F-HFB-CPCs' signal in the target area at 2h (18.6±10.3%ID) and 4h (3.9±2.0%ID) post-injection was greater than that of 18F-FDG-CPCs (10.2±6.6%ID versus 1.1±0.5%ID, respectively; p<0.05). Tissue biodistribution confirmed that 3.7±1.9%ID of radioactivity was detected in the border zone of 18F-HFB-CPC rats, compared to only 1.5±0.8 %ID in 18F-FDG-CPC rats (p<0.05). Immunostaining of heart tissue sections revealed no significant difference in cell retention between the two cell labeling groups (p=0.80). Good correlation (r=0.81, p<0.05) with biodistribution results was observed in the 18F-HFB-CPC group.
Conclusions: Compared to 18F-FDG labeling, labeling hCPCs with 18F-HFB provides a more efficient, stable, and accurate way to quantify cell delivery and distribution. 18F-HFB cell labeling with PET imaging offers a better modality to enhance our understanding of early retention, homing, and engraftment with cell cardiac therapy.
- Stem/progenitor cells
- Positron emission tomography
- Myocardial infarction
- Cardiac injection
- © 2010 by American Heart Association, Inc.