Experimental Study On Therapeutic Angiogenesis Of Sustained Release VEGF-dextran-PLGA Microspheres

Objective: To construct hindlimb ischemia model of rats and the rats were treated with fibrin gel containing VEGF-dextran-PLGA microspheres by intramuscular injection into Ischemia area.And to observe the growth of capillaries in the ischemic area.To evaluate the effect of promoting angiogenesis in the hindlimb ischemia of rats stimulating by VEGF-dextran-PLGA microspheres.Methods:1.The VEGF-dextran-PLGA microspheres were prepared by S/O/W solvent evaporation method.2.To study the characteristics of VEGF-dextran-PLGA microspheres in vitro.Scanning electron microscopy(SEM)images of VEGF-dextran-PLGA microspheres were obtained using SEM.3.The encapsulation rate and drug release performance of VEGF-dextran-PLGA microspheres were detected in vitro by enzyme-linked immunosorbent assay(ELISA).4.The hindlimb ischemia model of rats were constructed and the rats were divided into three groups,VEGF-PLGA group,VEGF group and PLGA group.5.The hindlimb Ischemia area of rats were injected with fibrin gel containing VEGF-dextran-PLGA microspheres,VEGF and dextran-PLGA,respectively.Muscle tissues of the ischemic hindlimb were collected for histological and immunohistochemical taining at 5 days and 28 days later.Results:1.VEGF-dextran-PLGA microspheres possessed spherical shapes,smooth surface and diameters range from 40 to 100 ?m,encapsulation efficiency for the VEGFdextran-PLGA microspheres was 85%±4.1,the cumulative release of VEGF was 89.7%,the amount of burst release was about 21.4% during the first two days,sustained release of VEGF for more than 4 weeks.2.VEGF-dextran-PLGA microspheres significantly increased the density of the capillaries and ?-SMA positive vessels at the injection site.3.VEGF-dextran-PLGA microspheres promoted the mobilization of CD34,c-kit and vascular endothelial growth factor receptor-2(VEGFR2)positive cells.Conclusion: Intramuscular injection of fibrin gel loaded with vegf-dextran-plga sustained-release microspheres can promote angiogenesis in ischemic tissues and it may be an ideal method for therapeutic neovascularization.