title: Sustained improvement in perfusion and flow reserve after temporally separated delivery of vascular endothelial growth factor and angiopoietin-1 plasmid deoxyribonucleic acid.
abstract: OBJECTIVE
  The 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.
  
  
  BACKGROUND
  Single 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.
  
  
  METHODS
  Unilateral 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.
  
  
  RESULTS
  In 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.
  
  
  CONCLUSIONS
  In conclusion, temporally separated VEGF and Ang-1 gene therapy results in sustained and functional neovascularization.
authors.affiliation: Division of Cardiology, Keenan Research Centre--Li Ka Shing Knowledge Institute, St. Michael's Hospital, University of Toronto, Ontario, Canada.
authors.forename: Alexandra H
authors.initials: AH
authors.lastname: Smith
authors.forename: Michael A
authors.initials: MA
authors.lastname: Kuliszewski
authors.forename: Christine
authors.initials: C
authors.lastname: Liao
authors.forename: Dmitriy
authors.initials: D
authors.lastname: Rudenko
authors.forename: Duncan J
authors.initials: DJ
authors.lastname: Stewart
authors.forename: Howard
authors.initials: H
authors.lastname: Leong-Poi
mesh_terms: D042683:Angiopoietin-1 / Q000235:genetics* / Q000627:therapeutic use*; D000818:Animals; D002908:Chronic Disease; D004247:DNA / Q000235:genetics / Q000627:therapeutic use; D004195:Disease Models, Animal; D018014:Gene Transfer Techniques; D006614:Hindlimb / Q000098:blood supply*; D007511:Ischemia / Q000628:therapy*; D008297:Male; D018919:Neovascularization, Physiologic / Q000187:drug effects*; D010957:Plasmids; D011897:Random Allocation; D051381:Rats; D017207:Rats, Sprague-Dawley; D060888:Real-Time Polymerase Chain Reaction; D012039:Regional Blood Flow; D042442:Vascular Endothelial Growth Factors / Q000235:genetics / Q000627:therapeutic use*
chemical_list: D042683:Angiopoietin-1; D042442:Vascular Endothelial Growth Factors; D004247:DNA