Efficacy Of Transplantation Of Vegf-expressing Bone Marrow Stromal Cells Into Ischemic Swine Myocardium And Pi3k/akt/sdf-1α Pathway Mediated Cardiomyocyte Protection Effect Of VEGF

Background: Ischemic heart disease is the major cause of morbility and mortality in the world. Although myocardial salvage due to early reperfusion therapy has significantly reduced early mortality rates, postinfarction heart failure resulting from ventricular remodeling remains a problem.One possible approach to reversing postinfarction heart failure is enhancement of the regeneration of cardiac myocytes as well as stimulation of neovascularization within the infarcted area. The purpose of this study is to evaluate the efficacy of t ransplantation of vascular endothelial growth factor (VEGF) - expressing bone marrow st romal cells (BMSCs) into ischemic swine myocardium .The cardiomyocyte protection effect of VEGF and the mechanism involved will also be studied.Methods and results: A swine model of chronic myocardial ischemia was made in this study. BMSCs were obtained f rom swines′breastbone marrow and cultured in vitro, then BMSCs were t ransfected with the human VEGF165 gene. Four weeks later, VEGF - expressing BMSCs (Combo group, n = 8), BMSCs (BMSCs cont rol group, n = 8) or saline water only (Control group, n = 6) was injected into swine heart s using lef t vent ricular elect romechanical (NOGA) mapping system and injection catheter. NOGA mapping, coronary angiography and echocardiography were conducted before and 4 weeks after cell transplantation. Rat neonatal ventricular myocytes were isolated and cultured in DMEM with 10% fetal bovine serum. Cardiomyocytes death was induced with H2O2 and VEGF was added to the culture medium. Expression of CXCR4c-20 and Akt and Akt phosphoratliation were was detected with Western blotting. Protein level and mRNA expression of SDF-1αand VEGF were detected with qRT-PCR and ELISA respectively. Cytoactivity and cell injury were measured with trypan blue dying assay and LDH activity detection. This study show that after four weeks after cell transplantation, combination therapy resulted in superior improvement in all indexes of perfusion and function compared with other two treatment groups (P < 0.05). Treatment of neonatal rat ventricular myocytes with VEGF stimulated phosphorylation of Akt in dose- and Flk-1- dependent manner. VEGF attenuated H2O2-induced cardiomyocytes death. LY294002, PI3K/Akt inhibitor and Flk-1 antibody abolished the beneficial effect of VEGF. Concomitantly, SDF-1αand its receptor, CXCR4, were up-regulated by VEGF through the PI3K-Akt signaling pathway, contributing to the protective effect of VEGF on H2O2-induced cell death. Furthermore, through the PI3K-Akt pathway, SDF-1αalso stimulated in vitro VEGF production, and prevented H2O2-induced cardiomyocyte death. In conclusion, these results suggest an Akt-centered loop, with VEGF and SDF-1αplaying critical roles in cardiomyocytes survival.Conclusion: These results provide the first evidence that that combined strategy of bone marrow stromal cell transplantation with VEGF gene therapy could be of importance for the treatment of myocardial infarction. And a crosstalk between VEGF and SDF-1αthrough PI3K-Akt serves a survival role in cardiomyocytes in vitro.