Analysis of Cell Aggregation In Thawed Hematopoietic Stem Cell Products Using Micro-Flow Imaging.
Bibliographic record
Abstract
Abstract Abstract 1187 Background: Cell aggregation can be observed after thawing cryopreserved hematopoietic stem cell products used in transplantation. Micro-flow imaging (MFI) is a novel method of imaging biologic fluids and provides a means of quantifying cell aggregation. Method: Umbilical cord blood (UCB) was collected following informed consent and cryopreserved in 5% DMSO and 37% (w/v) pentastarch in liquid nitrogen. Aliquots of cryopreserved peripheral blood progenitor cell (PBPC) products were cryopreserved under similar conditions. Cells were thawed rapidly and filtered before analysis using MFI. Result: Large cellular aggregates were identified in all thawed PBPC samples analyzed (n=4) with a mean reduction in total cells of 19.7 ± 9.8% at 1 hour and 49.8 ± 15.9% at 24 hours. Cellular aggregates ≤ 170 um were visualized, sized and digitally imaged with MFI. Analysis of larger clumps was limited due to size of the analysis chamber. Cell transparency and circularity were unchanged over 24h after thawing and similar to freshly isolated PBPCs. Mononuclear cell yields did not diminish over 24 hours in freshly isolated PBPC (n=3, p>0.05) or in fresh UCB (n=3, p>0.05). Thawed UCB samples did not demonstrate significant clumping and maintained higher yields of total cells compared with PBPCs (p=0.02). Filtering of thawed PBPC products using standard blood transfusion filters (Baxter, 170 um) did not change the qualitative nature of observed cellular aggregates. The loss of cells in PBPC products correlated with early apoptotic mononuclear cells (7AAD-AnnV+). Treatment with DNase I eliminated the presence of observable cell clumping in thawed PBPCs at 24h with a marked improvement in cell yield at 24h (p<0.0001). Conclusion: Micro-flow imaging provides novel insight regarding cellular aggregation of blood stem cell products. Significant cell clumping occurs in cryopreserved PBPC after thawing and aggregates are not removed by standard transfusion filters. Aggregation increases with time after thawing and may influence the final dose of cells available for engraftment after transplantation. Fresh PBPC collections contain few aggregates and both fresh and thawed cryopreserved UCB demonstrated minimal cell clumping. Apoptosis induced by cryopreservation and thawing may contribute to increased aggregation in PBPCs and DNase I appears to preserve higher yields of total cells. New cryoprotectants that limit apoptosis are needed and methods to reduce cell clumping appear warranted. Disclosures: Martin: Brightwell Technologies: Employment.
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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 | 0.000 | 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 | 0.001 |
| Insufficient payload (model declined to judge) | 0.002 | 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 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".