Overcoming the deceptively low viability of CD45<sup>+</sup> cells in thawed cord blood unit segments
Bibliographic record
Abstract
Background and objectives There is no standard methodology for post‐thaw sample preparation for viability analysis of umbilical cord blood units (CBU). A common challenge faced by CB bank is for their product to meet the post‐thaw cell viability threshold for CD45 + cells set at 40% by NetCord‐FACT. The objective of this work was to improve the post‐thaw staining method to maximize CD45 + cell viability so that clinically valuable samples meet the NetCord‐FACT threshold criteria for CD45 + and CD34 + cell viabilities. Materials and methods Samples of CBU buffy coats and CBU segments were thawed and taken for staining. Various parameters were evaluated on CD45 + and CD34 + cell viability as measured by 7‐actinomycin D (7‐AAD) staining. Results The results revealed that initiating the staining at 20 min post‐thaw instead of 30, shortening the red cell lysis treatment, or performing lysis on ice and removing this step all together, all improved the viability of CD45 + cells. Using CBU segments, it was shown that the most effective approach in increasing the viability of CD45 + cells was the complete omission of red cell lysis step. However, removal of the lysis step can create technical artefacts during flow cytometry acquisition that results in an underestimation of the viability of CD34 + cells. This can be avoided and CD34 + cell viability restored with additional thresholding on CD45 signal. Conclusion CB CD45 + cells are sensitive to red cell lysis treatment post‐thaw; omission of this step provides the best viability and ultimately better reflects the quality of cells used for transplantation.
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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 | 0.001 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 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) | 0.001 | 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".