Viability And Potency Of Hematopoietic Progenitor Cells After Prolonged Cryopreservation At -80 °C
Bibliographic record
Abstract
Hematopoietic progenitor cell (HPC) products cryopreserved in the liquid or vapor phase of liquid nitrogen (LN) remain viable and potent for years. Cryopreserved HPC products when stored at -80 °C in mechanical freezers are known to remain viable and potent for up to 180 days. We demonstrated viability and potency of HPC products stored at -80 °C for up to 12 years. Products were cryopreserved in 6% hydroxyethyl starch, 5% DMSO and 4% human serum albumin using non-controlled rate freezing. Thawed products were tested for viability and potency respectively by trypan blue dye exclusion and hematopoietic progenitor cell colony assay (CFU-GM, BFU-E, CFU-GEMM). All culture assays used MethoCult® GF+ H4445 (STEMCELL Technologies, Vancouver, BC, Canada). We thawed 20 HPC products collected from mobilized peripheral blood. The products were stored between 7 and 12 years at -80 °C. In 19 cases, trypan blue dye exclusion yielded an average 72% viability (range: 50%-89%). HPC colony assay yielded average progenitor frequencies of: CFU-GM 159 [range: 15-600]; BFU-E 116 [range: 2-388] and CFU-GEMM 21 [range: 2-68] all per 105 viable cells plated. The average values did not differ from control values of CFU-GM 111, BFU-E 121 and CFU-GEMM 23. Two products were infused into their donors after myeloablative conditioning, UPN 947 and UPN 1000. The products were stored for over 9 years. The products from UPN 947/UPN 1000 gave 73%/65% viability by trypan blue dye exclusion, CFU-GM 347/508, BFU-E 135/344, CFU-GEMM 12/48 per 105 viable cells, ANC500 day+14/day+11 and PLT50 day+15/day+24. We conclude that viability and potency of these HPC products flash-frozen and stored at -80 °C in pentastarch is maintained for up to 12 years. In two cases engraftment was achieved with long-term cryopreserved products. The data suggest that prolonged cryopreservation of HPC products using LN may not be necessary to preserve product potency.
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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) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.001 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.001 |
| Insufficient payload (model declined to judge) | 0.002 | 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".