Sustained Improvement in Perfusion and Flow Reserve After Temporally Separated Delivery of Vascular Endothelial Growth Factor and Angiopoietin-1 Plasmid Deoxyribonucleic Acid

ObjectivesThe aim of this study was to compare temporally separated vascular endothelial growth factor (VEGF) and angiopoietin (Ang)-1 delivery with concomitant delivery or single VEGF delivery, for therapeutic angiogenesis in chronic ischemia.BackgroundSingle gene delivery of VEGF results in immature neovessels that ultimately regress. Endogenously, VEGF acts early to initiate angiogenesis, whereas Ang-1 acts later to induce vessel maturation. Timing VEGF and Ang-1 gene delivery to mimic endogenous angiogenesis might be more effective for sustained neovascularization.MethodsUnilateral hindlimb ischemia was induced in 170 rats. Ultrasound-mediated gene delivery was performed with cationic microbubbles and plasmid deoxyribonucleic acid. Groups included VEGF at 2 weeks, VEGF/Ang-1 at 2 weeks, VEGF at 2 weeks with Ang-1 at 4 weeks, and untreated control subjects. At 2, 4, and 8 weeks after ligation, blood flow and flow reserve (FR) were assessed by contrast-enhanced ultrasound. Vascular density, organization, and supporting cell coverage were assessed by fluorescent microangiography and immunohistochemistry.ResultsIn untreated control subjects, blood flow, FR, and vessel density remained reduced. The VEGF delivery improved flow and vessel density at 4 weeks; however, FR remained low, supporting cell coverage was poor, and flow and vessel density regressed by 8 weeks. The VEGF/Ang-1 co-delivery marginally increased flow and vessel density; however, FR and supporting cell coverage improved. After temporally separated VEGF and Ang-1 delivery, blood flow, vessel density, and FR increased and were sustained, with improved pericyte coverage at 8 weeks.ConclusionsIn conclusion, temporally separated VEGF and Ang-1 gene therapy results in sustained and functional neovascularization.