Abstract 15747: Over-Expression of Insulin-Like Growth Factor-1 by Human Cardiac Stem Cells Enhances Long-Term Retention of Transplanted Cells While Promoting Salvage of Injured Myocardium
Bibliographic record
Abstract
Background: Insulin-like growth factor (IGF-1) is a potent pro-survival cytokine that is not robustly expressed by human cardiac stem cells (CSCs). Previously, we have shown that paracrine engineering of CSCs with IGF-1 improves cell-mediated cardiac repair. Here, we explore the mechanisms underlying IGF-1 enhanced cardiac repair by CSCs. Methods/Results: Sub-culture of isolated c-Kit+, CD90+ and lineage negative cells (c-Kit-/CD90-) demonstrated that the natural low level production of IGF-1 by CSCs (149±16 pg/ml*mg) is secreted by all 3 sub-populations. After culture in hypoxic reduced serum media, lentiviral mediated over-expression of IGF-1 enhanced proliferation (population doubling time: 1.4±1.7 vs.-0.9±1.2 and -1.9±2.4 days, respectively; p≤0.01), expression of pro-survival transcripts (AKT, ERK and MAPK pathways) and pro-survival proteins (Bcl-2, Bcl-x, HIF-1a; p≤0.01) while decreasing expression of apoptotic markers (3.5±0.9 and 3.7±0.9 fold less annexin V; p≤0.01) as compared to GFP- and non-transduced CSCs. The high expression of the IGF-1 (79±3%) or the insulin receptor (61±5%) on CSCs suggests that autocrine pro-survival pre-conditioning underlies these effects. Direct and indirect co-culture of CSCs with neonatal rat ventricular cardiomyocytes (NRVMs) within hypoxic conditions demonstrated that IGF-1 promoted indirect myocardial repair by increasing NRVM viability and pro-survival signaling (Bcl2+; p≤0.01) while reducing apoptosis (annexin V+; p≤0.05) as compared GFP- or non-transduced CSCs. Transplant of CSCs genetically engineered to over-express IGF-1 into immunodeficient mice one week after infarction boosted IGF-1 content within infarcted tissue by 2.9±0.2 fold (p=0.004) and long-term engraftment (+4 weeks human alu content increased by 9.1±4 fold; p=0.05) while reducing myocardial apoptosis (3.4±0.3 and 2.5±0.5 fold reduction expression of Bax and p53, respectively; p<0.05) and long-term myocardial scarring (+ 4 weeks 2.2±0.4 fold less; p=0.01) as compared to GFP-transduced CSCs. Conclusions: Transplantation of IGF-1 enriched CSCs enhances cardiac repair by boosting transplant cell survival and reducing myocardial apoptosis to improve myocardial function and salvage of damaged myocardium.
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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 | 0.001 |
| Insufficient payload (model declined to judge) | 0.007 | 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".