Combined Treatment With Erythropoietin And Granulocyte Colony-Stimulating Factor Enhances Neovascularization And Improves Cardiac Function After Myocardial Infarction

Background Erythropoietin(EPO)and granulocyte colony-stimulating factor(G-CSF)are both potential novel therapies after acute myocardial infarction(AMI).However,the underlying mechanisms remain unclear and the efficacy of monotherapy with EPO or G-CSF is also controversial.Therefore,we investigated the potential protective effects of EPO combinated with G-CSF on enhancing mobilization of endothelial progenitor cell(EPC)and modulating expression of pro-angiogenic genes and stem cell-related processes genes which facilitate homing and differentiation of EPCs and promote angiogenesis after AMI in rats.So as to reveal the molecular mechanisms of angiogenesis and provide new ideas for AMI treatment.Methods SD rats underwent permanent left anterior descending(LAD)coronary artery ligation.The experimental design consisted of four groups of rats: control(saline injection 1h after AMI,i.h.),EPO(a single dose of 5000IU/kg 1h after AMI,i.h.),G-CSF(a dose of 50?g/kg 1h after AMI and 50?g/kg/day for 5 consecutive days,i.h.),and both EPO and G-CSF(EPO+G-CSF,using the same regiment above).Cardiac function was assessed by echocardiography before and 1 day,7 days,14 days and 21 days after AMI.CD34+/Flk-1+ cells in the peripheral blood were evaluated by flow cytometry before and 3 days,5 days and 7 days after AMI.The mRNA and protein expression of VEGF were detected by real-time quantitative RT-PCR and Western blotting at 7 days and 21 days after AMI.SCF?SDF-1?MIP-1? and MCP-1 in the peri-infarct area were detected by real-time quantitative RT-PCR and Western blotting at 7 days after AMI,respectively.Infarct area,angiogenesis and apoptosis of myocyte in the peri-infarct area were analyzed at 21 days after AMI.Results Compared with the control and either monotherapy groups,EPO+G-CSF group significantly increased CD34+/Flk-1+ endothelial progenitor cells(EPCs)in the peripheral blood at 3 days?5 days?7 days after AMI,up-regulated VEGF expression in the peri-infarct region at 7 days and 21 days after AMI,up-regulated SCF?SDF-1 and down-regulated MIP-1??MCP-1 expression in the peri-infarct region at 7 days after AMI,enhanced capillary density,inhibited apoptosis,reduced infarct size and improved cardiac structure and function at 21 days after AMI.Besides,G-CSF alone didn't dramatically increased EPCs in the peripheral blood,enhanced capillary density in the peri-infarct area or reduced infarct size compared with the control group.Conclusions Combined treatment with EPO and G-CSF increased EPCs mobilization,inhibited apoptosis and up-regulated VEGF?SCF?SDF-1 expression in the postinfarction microenvironment,subsequently enhanced neovascularization in the peri-infarct region and reduced infarct size,which contributed to its beneficial effects on cardiac function in postinfarction rats.