High-resolution tracking of cell division suggests similar cell cycle kinetics of hematopoietic stem cells stimulated in vitro and in vivo
Bibliographic record
Abstract
The kinetics of proliferation of primitive murine bone marrow (BM) cells stimulated either in vitro with growth factors (fetal liver tyrosine kinase ligand 3 [FL], Steel factor [SF], and interleukin-11 [IL-11], or hyper-IL-6) or in vivo by factors active in myeloablated recipients were examined. Cells were first labeled with 5- and 6-carboxyfluorescein diacetate succinimidyl ester (CFSE) and then incubated overnight prior to isolating CFSE(+) cells. After 2 more days in culture, more than 90% of the in vivo lymphomyeloid repopulating activity was associated with the most fluorescent CFSE(+) cells (ie, cells that had not yet divided), although this accounted for only 25% of the repopulating stem cells measured in the CFSE(+) "start" population. After a total of 4 days in culture (1 day later), 15-fold more stem cells were detected (ie, 4-fold more than the day 1 input number), and these had become (and thereafter remained) exclusively associated with cells that had divided at least once in vitro. Flow cytometric analysis of CFSE(+) cells recovered from the BM of transplanted mice indicated that these cells proliferated slightly faster (up to 5 divisions completed within 2 days and up to 8 divisions completed within 3 days in vivo versus 5 and 7 divisions, respectively, in vitro). FL, SF, and ligands which activate gp130 are thus efficient stimulators of transplantable stem cell self-renewal divisions in vitro. The accompanying failure of these cells to accumulate rapidly indicates important changes in their engraftment potential independent of accompanying changes in their differentiation status.
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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) | 0.001 | 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 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".