Transmyocardial Revascularization Enhances Bone Marrow Stem Cell Engraftment in Infarcted Hearts Through SCF-C-kit and SDF-1-CXCR4 Signaling Axes.

Abstract

We investigated the roles of stem cell factor (SCF)-c-kit and stromal derived factor-1 (SDF-1)-CXCR4 signaling axes in transmyocardial revascularization (TMR)-enhanced engraftment of transplanted bone marrow stem cells (BMSCs) in infarcted hearts. 3weeks after LAD ligation, female Lewis rats underwent 10-channel needle-TMR, followed by daily IV injections of 1 million male donor BMSC for 5days, either wild type (WT) or with knockdown (K/D) of c-kit or CXCR4, accomplished via a shRNA + plasmid in a lentiviral vector (N = 6/group). In our rat infarct model, 3days after last BMSC injection, the number of BMSCs that homed into infarct was affected by both TMR and donor cell type, with greater BMSC engraftment with TMR and with WT BMSC (TMR, cell type, and interaction, P < 0.05). At 1week, these differences persisted (TMR and cell type, P < 0.05). At 3days, TMR significantly upregulated transcription of c-kit (TMR, p < 0.05), SCF (TMR and cell type, P < 0.05), CXCR4 (TMR and cell type, p < 0.05), and SDF-1 (TMR and cell type, P < 0.05). At 1week, we saw similar declines in expression of c-kit (cell type, P < 0.05), SCF (TMR, P < 0.05), CXCR4 (TMR and cell type, P < 0.05), and SDF-1 (TMR, P < 0.05). At 1week, TMR improved LV ejection fraction (LVEF) (N = 5) when WT BMSCs were infused, but knockdown of either c-kit or CXCR4 completely abrogated this TMR-mediated augmentation of BMSC reparative effect (TMR and cell type, P < 0.05). Downregulation of either c-kit or CXCR4 in BMSC decreased engraftment of circulating BMSC and inhibited reparative effects of TMR.