Abstract 12456: Apelin Expressing Endothelial Stem-Like Cells Orchestrate Lung Microvascular Repair in a Model of Lung-Targeted Endothelial Cell Ablation
Bibliographic record
Abstract
Introduction: Endothelial damage plays a central role in acute lung injury (ALI) contributing to alveolar leak and inflammatory cell trafficking. In preclinical models of ALI, repair and regeneration of lung vascular endothelium is required for its resolution. Therefore, we sought to define the cellular and molecular mechanisms underlying lung microvascular regeneration in acute lung injury induced by lung endothelial cell (EC) ablation. Methods and Results: Transgenic mice were created expressing endothelial-targeted human diphtheria toxin receptor. Intratracheal instillation of diphtheria toxin (DT) resulted in the ablation of ~70% of lung endothelial cells, producing severe acute lung injury, with complete resolution by 7 days. Changes in global lung cell populations and gene expression profiles were determined using single-cell RNA sequencing of dissociated lung cells (10x Genomics) at baseline (day 0), 3, 5 and 7 days after lung EC ablation. Single cell analysis revealed 8 distinct EC clusters, including type-A capillary ECs which were characterized by the unique expression of apelin at baseline. DT-induced EC ablation resulted in the emergence of novel endothelial stem-like cells within a transient population of ‘general’ capillary ECs, characterized by the de novo expression of apelin at day 3 post injury. As well, this population exhibited unique expression of the vascular endothelial stem cell marker, protein C receptor, together with the progenitor cell marker, CD34. This was followed by the appearance of proliferative ECs at day 5 expressing apelin receptor and the transcription factor, FoxM1, and these cells were responsible for replenishment of all depleted EC populations. Finally, treatment with an apelin receptor antagonist, ML221, prevented lung microvascular recovery and resulted in death at 4-5 days post DT. Conclusion: Targeted EC ablation revealed a remarkable regenerative capacity of the lung microvasculature. Using single cell transcriptomics, we have demonstrated that lung microvascular repair was orchestrated by newly emergent apelin-expressing endothelial stem-like cells.
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How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.001 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.000 |
| Bibliometrics | 0.000 | 0.001 |
| 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) | 0.000 | 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 teacher head, 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".