Stem cell transplantation and therapeutic gene delivery have shown promise in cardiovascular therapeutics. We hypothesized that concomitant mobilization of the resident cardiac stem cells (CSCs) and bone marrow stem cells (BMSCs) and their homing into the infarcted myocardium will be an effective strategy for myocardial regeneration. The rationale for this study is to exploit the diverse properties of CSCs and BMSCs, and varying mechanisms of action of different cytokines in myocardial regeneration following infarction. We anticipate that transplantation of Sca-1+ cells genetically modified to overexpress hepatocyte growth factor (HGF), stromal cell derived factor-11 (SDF-11) and insulin-like growth factor (IGF-1) will develop favorable chemotactic gradient in the heart. The locally developed gradient of HGF and SDF-11 will favor mobilization and homing-in of CSCs and BMSCs. Additionally, SDF-11 will provide retention signals for the chemokine receptor CXCR4 positive BMSCs for long enough time duration to ensure their participation and commitment to the repair process. IGF-1 overexpression will stimulate IGF-1/IGF-1R ligand-receptor system to activate PI3K/Akt signaling to promote proliferation and differentiation of these cells. The mobilized and transplanted stem cells will further contribute to the repair process by the release of trophic factors to exert paracrine effects. The main hypothesis will be studied in three specific Aims.
Aim -1 is intended to develop chemotactic gradient of cytokines to favor simultaneous mobilization and recruitment of CSCs and BMSCs in the infarcted heart.
Aim -2 will elucidate the angiogenic and myogenic fate and functional benefits of the mobilized cells.
Aim -3 will determine the role of cytokine priming of stem cells by preconditioning or by gene modification for protracted cytokines expression to promote their survival after transplantation. We anticipate that simultaneous mobilization of CSCs and BMSCs together with cytokine priming will augment their engraftment and upregulate survival factors thus preventing apoptosis and necrosis in the infarcted myocardium. Based on the anticipated beneficial effects of our multimodal therapeutic approach, the proposed study will show the significance of simultaneous mobilization of BMSCs and resident CSCs. The information thus obtained from these studies will likely lead to new therapeutic approaches for management of cardiovascular pathologies. NARRATIVE: Bone marrow derived stem cells and resident cardiac stem cells have shown promise in myocardial repair. Our proposal is based on concomitant mobilization of both these stem cell populations by multiple cytokine therapy.
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