Validation of a rapid potency assay for cord blood stem cells using phospho flow cytometry: The <scp>IL‐3‐pSTAT5</scp> assay
Bibliographic record
Abstract
Abstract Introduction Public cord blood banks (CBBs) are required to measure cord blood units (CBUs) potency before their release, allowing for the identification of units that may be unsuitable for haematopoietic transplantation. We have developed a rapid flow cytometry assay based on the measurement of STAT‐5 phosphorylation of CD34+ stem cells in response to IL‐3 stimulation. Method To adapt the assay from a research setting to its implementation within our CBB regulated operations, we proceded with a full method validation and a correlation comparison of the IL‐3‐pSTAT5 assay results with the colony‐forming unit assay (CFU) results. A total of 60 CBUs cryopreserved in vials were analysed by flow cytometry to determine the sensitivity, specificity, intra‐assay precision, robustness, reproducibility, and inter‐laboratory agreement of the assay. The CFU assay was also done on the same samples for comparison purposes. Results The assay threshold was established at 50% CD34+CD45+pSTAT5+, which provides a 100% sensitivity and a 98.3% specificity. An average intra‐assay CV of 7.3% was determined. All results met our qualitative results acceptance criteria regarding the inter‐user and inter‐laboratory agreements, IL‐3 stimulation time, post‐thaw incubation delay and staining time. The IL‐3‐pSTAT5 assay results correlated well with the total CFU determined using the CFU assay ( r 2 = 0.82, n = 56). Conclusion This study shows that our rapid flow cytometry assay can be successfully validated and that the potency data obtained display good sensitivity, specificity and robustness. These results demonstrate the feasibility of implementing this assay within CBB operations, as a validated potency assay.
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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 | 0.003 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.000 |
| Bibliometrics | 0.001 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| 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".