Upregulation of MT1-MMP by Molecules Present in Leukaphereis Products Primes CD34+ Cell Homing.
Bibliographic record
Abstract
Abstract Hematopoietic stem/progenitor cells (HSPC) derived from mobilized peripheral blood engraft faster than those from bone marrow (BM) or cord blood (CB). We recently postulated that leukapheresis product supernatants (collected from G-CSF-mobilized patients) and their components (fibrinogen, fibronectin, thrombin, hyaluronic acid (HA) and C3 cleavage fragments) have a priming effect on HSPC homing by enhancing chemotactic responses to SDF-1 through increased incorporation of CXCR4 into membrane lipid rafts and stimulation of matrix metalloproteinase (proMMP-2 and proMMP-9) secretion in these cells (Blood2005; 105:40). As MT1-MMP has been shown to activate latent forms of MMP-2 and (indirectly) MMP-9 and is known to localize proteolytic activity at the leading edge of migrating cells, we decided to investigate MT1-MMPs’ role in the priming of HSPC homing. We observed that stimulation of BM and CB CD34+ cells with priming agents (HA, fibrinogen or thrombin) not only increased secretion of proMMP-2 and proMMP-9 (zymography) but also highly upregulated levels of MT1-MMP transcript (RT-PCR) and protein (Western blotting) in these cells. Moreover, trans-Matrigel chemoinvasion of CD34+ cells towards a low SDF-1 gradient (20 ng/mL), enhanced by priming agents, was inhibited by the potent MT1-MMP inhibitor epigallocatechin-3-gallate. Furthermore, priming agents (HA, fibrinogen and thrombin) increased levels of active MMP-2 in co-cultures of stromal cells (endothelial cells and BM fibroblasts) with CD34+ cells. To elucidate the mechanism of MT1-MMP upregulation by priming agents, we evaluated whether they affected MT1-MMP incorporation in ganglioside M1-enriched membrane lipid rafts in the same way as for CXCR4. We found that stimulation of hematopoietic and THP-1 cells with HA, fibrinogen and thrombin increased incorporation of MT1-MMP into membrane lipid rafts and these observations were confirmed using confocal microscopy. Hence it appears that MT1-MMP, like CXCR4, localizes in membrane lipid rafts, and this is enhanced by priming agents, leading to better homing of HSPC.
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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) | 0.002 | 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".