Effects of interruptions of controlled‐rate freezing on the viability of umbilical cord blood stem cells
Bibliographic record
Abstract
BACKGROUND: An optimal cooling rate is critical for cryopreserving cord blood stem cells, so it is generally achieved by using controlled-rate freezers (CRFs). The cooling rate can be interrupted by many factors during cooling; therefore, a proper response to the interruption in cryopreservation is crucial to prevent the loss of valuable cells. STUDY DESIGN AND METHODS: Cord blood samples (n = 6) containing 10% dimethyl sulfoxide were cooled from 4 to -80°C using a CRF. At different temperatures during cooling, cells were transferred either to liquid nitrogen vapor phase (LNVP) directly or a -80°C mechanical freezer where they were stored for 18.1 ± 0.6 hours before transferring to LNVP. The cells were stored in LNVP for 127 ± 48.1 hours before postthaw recovery, viability, and survival of total nucleated cells and/or CD45+ cells, CD34+ cells, and colony-forming unit-granulocyte-macrophage (CFU-GM) were assessed. RESULTS: For all types of postthaw evaluations, there were no significant differences when cells were transferred to a -80°C freezer before LNVP, regardless of the temperature at which cooling was interrupted. In contrast, there were significant differences when cells were transferred to LNVP directly, but the differences were determined by the type of assays and how viability was calculated. CONCLUSIONS: Cord blood samples can be transferred to a -80°C freezer anytime during controlled-rate cooling, but should only be transferred to LNVP when the samples have been cooled to -40°C or lower. Percent postthaw survival of CFU-GM should be routinely assessed when controlled-rate cooling is interrupted.
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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) | 0.001 | 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) | 0.000 | 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".