OP9 Stroma Augments Survival of Hematopoietic Precursors and Progenitors During Hematopoietic Differentiation from Human Embryonic Stem Cells
Bibliographic record
Abstract
The cellular mechanism and target cell affected by stromal microenvironments in augmenting hematopoietic specification from pluripotent human embryonic stem cells (hESCs) has yet to be evaluated. Here, in contrast to aorta-gonad-mesonephros-derived S62 stromal cells, OP9 cells inhibit apoptosis and also augment the proliferation of hemogenic precursors prospectively isolated from human embryoid bodies. In addition, OP9 stroma supported cells within the primitive hematopoietic compartment by inhibiting apoptosis of CD45(+)CD34(+) cells committed to the hematopoietic lineage, but have no effect on more mature blood (CD45(+)CD34(-)) cells. Inability of hESC-derived hematopoietic cells cocultured with OP9 stromal cells to engraft in both the adult and newborn NOD/SCID mice after intrafemoral and intrahepatic injection illustrated that although OP9 stromal cells augment hESC-derived hematopoiesis and progenitor output, this optimized environment does not confer or augment repopulating function of specified hematopoietic cells derived from hESCs. OP9 coculture also increases hematopoietic progenitors output from hemogenic precursors overexpressing HOXB4. Our study demonstrates that OP9 cells support both hemogenic precursors and their primitive hematopoietic progeny, thereby providing the first evidence toward understanding the cellular targets and mechanisms underlying the capacity of OP9 stromal cells to support hematopoiesis from ESCs and define the future steps required to achieve the global goal of generating bona fide human hematopoietic stem cells from ESC lines. Disclosure of potential conflicts of interest is found at the end of this article.
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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".