VEGF-modified Macrophages Transdifferentiate Into Endothelial-like Cells, Target To Infarcted Myocardium And Improve Neovascularization And Cardiac Function

PARTâ… VEGF-modified macrophages transdifferentiate into endothelial-like cells in vitro and in vivoBackgroundMonocytes/macrophages display a high degree of plasticity, as demonstrated by their ability to transdifferentiate into endothelial cells (ECs), endothelial progenitor cells (EPCs) or endothelial-like cells (ELCs) in vitro and in vivo. These findings indicate a potential developmental relationship between monocytes/macrophages and endothelial cells and suggest that the monocytes/macrophages would be an appropriate candidate source for ECs, EPCs or ELCs. Vascular endothelial growth factor (VEGF), the most potent direct-acting angiogenic protein known, induces endothelial cell differentiation. The role of VEGF overexpression in regulating the phenotype and function of macrophages in vitro and in vivo remains unknown.ObjectiveTo investigat if VEGF-modified mouse monocytes/macrophages could transdifferentiate into endothelial-like cells (ELCs) in vitro and in vivo.Methods(1) in vitro:Murine monocyte macrophage cell line RAW264.7 cells were transfected with pCR2.1-hVEGF165. The expression of genes and proteins for various endothelial markers were examined by real-time PCR, flow cytometry and immunofluorescence. The formation of tubular structures was studied in ECM gel cultures. (2) in vivo:Peritoneal macrophages were isolated from GFP transgenic mice and transfected with pCR2.1-hVEGF165. A model of myocardial infarction (MI) in Wild type C57BL/6 mice was induced by left coronary artery ligation. These mice were received VEGF-modified macrophages immediately after induction of MI. At 7 days post-MI, the early formation of new blood vessel in sections of heart was observed by immunofluorescence microscopy.ResultsThe results revealed that VEGF-modified macrophages significantly expressed fetal liver kinase 1 (FLK-1), vascular endothelial cadherin (VE-cadherin), CD31, Von Willebrand factor (vWF), endothelial nitric oxide synthase (eNOS) and CD 105. When cultured in ECM gel for 24 h, VEGF-modified macrophages formed tube-like structures. Furthermore, in a model of myocardial infarction (MI), macrophages overexpressing VEGF incorporated into blood vessels.ConclusionThese data indicate that macrophages overexpressing VEGF transdifferentiate into endothelial-like cells (ELCs) in vitro and in vivo. PART IIVEGF-modified macrophages target to infarcted myocardium and improve neovascularization and cardiac functionBackgroundAccumulating research of vascular endothelial growth factor (VEGF) gene therapy has proven that VEGF has beneficial effects on the ischemic heart disease; however, the lack of a delivery system targeted to the injured myocardium reduces the local therapeutic efficacy of VEGF and increases its possible adverse effects. Monocytes/macrophages dominate the cellular infiltrate for the first two weeks after myocardial infarct (MI) and participate in infarct wound healing. In this study we speculated that VEGF-modified macrophages may act as a carrier of VEGF and be naturally recruited to ischemic myocardial tissue to repair myocardial infarct.ObjectiveTo investigat if VEGF-modified mouse macrophages could target to ischemic myocardial tissue to induce neovascularization and improve cardiac function.MethodsPeritoneal macrophages were isolated from mice and transfected with pCR2.1-hVEGF165. A model of myocardial infarction (MI) in mice was induced by left coronary artery ligation. These animals were randomly divided into following groups:MI group (received PBS by tail vein immediately after induction of MI); Macrophage group (received untreated macrophages in PBS); VEGF-macrophage group (received VEGF-modified macrophages in PBS); and sham-operated group. At 7 days post-MI, protein expression of VEGF in border zone myocardium was examined by western blot. At 28 days post-MI, cardiac function was detected by hemodynamics and capillary density in the border zone was evaluated by immunofluorescence.ResultsAt 7 days post-MI, the level of VEGF protein expression in myocardial tissue from the border zone was significantly increased in all the mice that had undergone the MI procedure compared with sham-operated mice, and the level of VEGF expression in VEGF-macrophage group was much higher than that of in the MI group and Macrophage group. At 28 days post-MI, cardiac function was significantly improved in VEGF-macrophage group. In addition, a significant increased capillary density in border zone was found in VEGF-macrophage group.ConclusionVEGF-modified mouse macrophages could target to ischemic myocardial tissue to induce neovascularization and improve cardiac function.