<sup>18</sup> F-FDG Cell Labeling May Underestimate Transplanted Cell Homing: More Accurate, Efficient, and Stable Cell Labeling with Hexadecyl-4-[ <sup>18</sup> F]Fluorobenzoate for in Vivo Tracking of Transplanted Human Progenitor Cells by Positron Emission Tomography
Bibliographic record
Abstract
Cell therapy is expected to restore perfusion and improve function in the ischemic/infarcted myocardium; however, the biological mechanisms and local effects of transplanted cells remain unclear. To assess cell fate in vivo, hexadecyl-4-[(18)F]fluorobenzoate ((18)F-HFB) cell labeling was evaluated for tracking human circulating progenitor cells (CPCs) with positron emission tomography (PET) and was compared to the commonly used 2-[(18)F]fluoro-2-deoxy-d-glucose ((18)F-FDG) labeling method in a rat myocardial infarction model. CPCs were labeled with 18F-HFB or (18)F-FDG ex vivo under the same conditions. (18)F-HFB cell-labeling efficiency (23.4 ± 7.5%) and stability (4 h, 88.4 ± 6.0%) were superior to (18)F-FDG (7.6 ± 4.1% and 26.6 ± 6.1%, respectively; p < 0.05). Neither labeling approach significantly altered cell viability, phenotype or migration potential up to 24 h postlabeling. Two weeks after left anterior descending coronary artery ligation, rats received echo-guided intramyocardial injection in the infarct border zone with (18)F-HFB-CPCs, (18)F-FDG-CPCs, (18)F-HFB, or (18)F-FDG. Dynamic PET imaging of both (18)F-HFB-CPCs and(18)F-FDG-CPCs demonstrated that only 16-37% of the initial injection dose (ID) was retained in the injection site at 10 min postdelivery, and remaining activity fell significantly over the first 4 h posttransplantation. The (18)F-HFB-CPC signal in the target area at 2 h (23.7 ± 14.7% ID/g) and 4 h (17.6 ± 13.3% ID/g) postinjection was greater than that of (18)F-FDG-CPCs (5.4 ± 2.3% ID/g and 2.6 ± 0.7% ID/g, respectively;p < 0.05). Tissue biodistribution confirmed the higher radioactivity in the border zone of (18)F-HFB-CPC rats. Immunostaining of heart tissue sections revealed no significant difference in cell retention between two labeled cell transplantation groups. Good correlation with biodistribution results was observed in the (18)F-HFB-CPC rats (r = 0.81, p < 0.05). Compared to (18)F-FDG, labeling human CPCs with(18)F-HFB provides a more efficient, stable, and accurate way to quantify the distribution of transplanted cells. (18)F-HFB cell labeling with PET imaging offers a better modality to enhance our understanding of early retention, homing, and engraftment with cardiac cell therapy.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.001 | 0.001 |
| Meta-epidemiology (narrow) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.001 |
| Scholarly communication | 0.001 | 0.001 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.001 | 0.001 |
| Insufficient payload (model declined to judge) | 0.001 | 0.001 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".