Identification and differentiation of PDX1 β-cell progenitors within the human pancreatic epithelium
Bibliographic record
Abstract
AIM: To minimize the expansion of pancreatic mesenchymal cells in vitro and confirm that β-cell progenitors reside within the pancreatic epithelium. METHODS: Due to mesenchymal stem cell (MSC) expansion and overgrowth, progenitor cells within the pancreatic epithelium cannot be characterized in vitro, though β-cell dedifferentiation and expansion of MSC intermediates via epithelial-mesenchymal transition (EMT) may generate β-cell progenitors. Pancreatic epithelial cells from endocrine and non-endocrine tissue were expanded and differentiated in a novel pancreatic epithelial expansion medium supplemented with growth factors known to support epithelial cell growth (dexamethasone, epidermal growth factor, 3,5,3'-triiodo-l-thyronine, bovine brain extract). Cells were also infected with a single and dual lentiviral reporter prior to cell differentiation. Enhanced green fluorescent protein was controlled by the rat Insulin 1 promoter and the monomeric red fluorescent protein was controlled by the mouse PDX1 promoter. In combination with lentiviral tracing, cells expanded and differentiated in the pancreatic medium were characterized by flow cytometry (BD fluorescence activated cell sorting), immunostaining and real-time polymerase chain reaction (PCR) (7900HT Fast Realtime PCR System). RESULTS: In the presence of 10% serum MSCs rapidly expand in vitro while the epithelial cell population declines. The percentage of vimentin(+) cells increased from 22% ± 5.83% to 80.43% ± 3.24% (14 d) and 99.00% ± 0.0% (21 d), and the percentage of epithelial cells decreased from 74.71% ± 8.34% to 26.57% ± 9.75% (14 d) and 4.00% ± 1.53% (21 d), P < 0.01 for all time points. Our novel pancreatic epithelial expansion medium preserved the epithelial cell phenotype and minimized epithelial cell dedifferentiation and EMT. Cells expanded in our epithelial medium contained significantly less mesenchymal cells (vimentin(+)) compared to controls (44.87% ± 4.93% vs 95.67% ± 1.36%; P < 0.01). During cell differentiation lentiviral reporting demonstrated that, PDX1(+) and insulin(+) cells were localized within adherent epithelial cell aggregates compared to controls. Compared to starting islets differentiated cells had at least two fold higher gene expression of PDX1, insulin, PAX4 and RFX (P < 0.05). CONCLUSION: PDX1(+) cells were confined to adherent epithelial cell aggregates and not vimentin(+) cells (mesenchymal), suggesting that EMT is not a mechanism for generating pancreatic progenitor cells.
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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 | 0.001 |
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".