Postnatal conservation of human blood- and marrow-specific CD34+ hematopoietic phenotypes
Bibliographic record
Abstract
Previous studies of aging have revealed intrinsically determined alterations in the properties of the hematopoietic stem cell (HSC) and progenitor compartments in mice, with variable evidence of an extension of these findings to humans. To examine more closely the surface phenotypes within the CD34 + compartment of human blood and bone marrow from birth to old age, we undertook a 13-parameter phenotypic profile analysis of samples from healthy human donors aged 0–76 years. The results indicate a conserved stability of canonically defined phenotype frequencies within the CD34 + compartment across this age spectrum, in contrast to previously reported losses of historically defined progenitor phenotypes associated with lymphoid-restricted outputs with advancing age. Interestingly, multidimensionality reduction of the data also produced an unexpected age-independent landscape that, nevertheless, revealed conserved phenotypic differences between cells isolated from blood or bone marrow samples. These source-specific differences were most notable in the HSC-enriched CD34 + CD38 – CD45RA – CD90 + CD49f + fraction, where they were driven largely by differences in cell surface expression of CD34, CD45, CD90, and CD38. Coordinated changes in the expression of several surface markers were also observed during downstream transitions within the CD34 + compartment, suggesting potential new strategies for isolating cell types with more narrowly defined functional properties. Overall, these findings indicate a general conservation during human aging of the phenotypic changes that segregate the major historically defined stages of differentiation within the human CD34 + compartment and underscore the selection processes that govern those that enter the circulation or alter their phenotypes therein.
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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 | 0.000 |
| 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 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".