A manganese porphyrin-based T1 contrast agent for cellular MR imaging of human embryonic stem cells
Bibliographic record
Abstract
Abstract MRI for non-invasive cell tracking is recognized for enabling pre-clinical research on stem cell therapy. Yet, adoption of cellular imaging in stem cell research has been restricted to sites with experience in MR contrast agent synthesis and to small animal models that do not require scaled-up synthesis. In this study, we demonstrate the use of a gadolinium-free T1 contrast agent for tracking human embryonic stem cells. The agent, MnPNH 2 , is an easily synthesized manganese porphyrin that can be scaled for large cell numbers. MRI was performed on a 3 T clinical scanner. Cell pellets labeled at different MnPNH 2 concentrations for 24 hours demonstrated a decrease in T1 relaxation time of nearly two-fold ( P < 0.05), and cellular contrast was maintained for 24 hours ( P < 0.05). Cell viability (Trypan blue) and differentiation (embryoid body formation) were unaffected. Cell uptake of Mn on inductively coupled plasma atomic emission spectroscopy corroborated MRI findings, and fluorescence microscopy revealed the agent localized mainly in cell-cell boundaries and cell nuclei. Labeled cells transplanted in rats demonstrated the superior sensitivity of MnPNH 2 for in-vivo cell tracking.
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How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.002 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.001 |
| Science and technology studies | 0.001 | 0.001 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.000 | 0.000 |
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 teacher head, 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".