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 therapeutics for use after myocardial infarction （MI）.However,their underlying mechanisms remain unclear and the efficacy of monotherapy with EPO or G-CSF is also controversial.Therefore,we investigated the effects of combined treatment with EPO and G-CSF on neovascularization and cardiac function in post-infarction rats and explored the potential mechanisms.Methods Four groups of rats were used：control （saline injection after MI,i.h.）,EPO （a single dose of 5 000 IU/kg after MI,i.h.）,G-CSF （a dose of 50 μg· kg-1· d-1 for 5 days after MI,i.h.）,and both EPO and G-CSF （EPO＋G-CSF,using the same regiment as above）.Cardiac function was assessed by echocardiography before and 1 day,7 days,14 days and 21 days after MI.CD34＋/Flk-1＋ cells in the peripheral blood were evaluated by flow cytometry before and 3 days,5 days and 7 days after MI.The infarct area and angiogenesis in the peri-infarct area were analyzed.The mRNA and protein expression of vascular endothelial growth factor （VEGF） and stromal-derived factor-1α （SDF-1α） in the peri-infarct area were detected by real-time quantitative RT-PCR and Western blotting.Results Compared with the control and monotherapy groups,the EPO＋G-CSF group had significantly increased CD34＋/ Flk-1＋ endothelial progenitor calls （EPCs）in the peripheral blood （P ＜0.05）,up-regulated VEGF and SDF-1α levels in the peri-infarct region （P ＜0.05）,enhanced capillary density （P ＜0.05）,reduced infarct size （P ＜0.05） and improved cardiac structure and function （P ＜0.05）.G-CSF alone did not dramatically increase EPCs in the peripheral blood,enhance capillary density in the peri-infarct area or reduce infarct size compared with the control group.Conclusions Combined treatment with EPO and G-CSF increased EPCs mobilization,up-regulated VEGF and SDF-1α levels in the post-infarction microenvironment,subsequently enhanced neovascularization in the peri-infarct region and reduced infarct size.All factors contributed to its beneficial effects on cardiac function in post-infarction rats.