Hematopoietic Stem and Progenitor Cells from Human Pluripotent Stem Cells Via Transcription Factor Conversion of Hemogenic Endothelium
Bibliographic record
Abstract
Abstract A variety of tissues can be differentiated from pluripotent stem cells (PSCs) in vitro through stepwise exposure to morphogens, or by conversion of one differentiated cell type into another by enforced expression of master transcription factors (TFs). Despite considerable effort, neither approach has yielded functional human hematopoietic stem cells (HSCs). Building upon recent evidence that HSCs derive from definitive hemogenic endothelium (HE), we performed morphogen-directed differentiation of human PSCs into HE followed by screening of 26 candidate HSC-specifying TFs for the capacity to promote multi-lineage hematopoietic engraftment in irradiated immune deficient murine hosts. From genomic PCR of engrafted cells, we recovered seven TFs (ERG, HOXA5, HOXA9, HOXA10, LCOR, RUNX1, SPI1) that were sufficient to convert HE into hematopoietic stem and progenitor cells (HSPCs) that engraft GLY-A+ erythrocytes, CD33+ myeloid, CD15+ CD31+ neutrophils, CD19+ IgM+ B and CD3+ T cells in primary and secondary murine recipients for 12-14 weeks. Limiting dilution analysis indicated that the frequency of repopulating cells generated by this method was 1 in 4,707-15,029, lower than the frequency in CD34+ cord blood cells (1 in 1,819-5,173). Functional characterization of terminally differentiated cells demonstrated features of definitive erythropoiesis (expression of adult beta globin and enucleation). Engrafted neutrophils responded to cytokine stimuli by activation of myeloperoxidase. Human IgM and IgG could be detected in the serum of engrafted mice, and titers of ovalbumin specific antibody increased in response to protein immunization, indicating boostable immunity. T-cells responded to PMA/Ionomycin stimuli by activation of IFNγ, and sequencing of the T cell receptor revealed a broad clonotype diversity. Proviral integration analysis demonstrated derivation of myeloid and lymphoid progeny from common clones in secondary animals, indicating generation of self-renewing, multipotential HSC-like cells from PSCs. Mechanistically, the seven TFs induced HOXA target genes (LMO2, SOX4, MEIS1 and ID2); upregulated expression of homing-related genes (CXCR4, VLA5 and S1PR1); and enhanced the endothelial to hematopoietic transition (EHT), as indicated by a 2.4-fold induction of a RUNX1c-reporter. Our combined approach of morphogen-driven differentiation and TF-mediated cell fate conversion produced HSPCs from PSCs that hold promise for modeling hematopoietic disease in humanized mice and for therapeutic strategies in genetic blood disorders. Disclosures No relevant conflicts of interest to declare.
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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) | 0.002 | 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".