Cotransfection of vascular endothelial growth factor-A and platelet-derived growth factor-B via recombinant adeno-associated virus resolves chronic ischemic malperfusion role of vessel maturation.
OBJECTIVE
We set out to investigate the ability of cardiotropic adeno-associated viral vector (AAV2.9 = recombinant adeno-associated virus [rAAV]) to induce prolonged expression of vascular endothelial growth factor (VEGF)-A and platelet-derived growth factor (PDGF)-B in a rabbit hindlimb ischemia model and a pig model of hibernating myocardium.


BACKGROUND
Gene therapy to induce angiogenesis and arteriogenesis has produced mixed results. However, long-acting viruses, such as rAAV, as well as combined induction of angiogenesis and vessel maturation might extend the therapeutic potential.


METHODS
In rabbits, 0.5 x 10(11) particles rAAV.VEGF-A with or without 1 x 10(12) particles rAAV.PDGF-B were retroinfused at day 7 after femoral artery excision. At days 7 and 35, collateral counts and perfusion were determined, each value given as the day 35/day 7 ratio. Capillary-to-muscle fiber ratio was determined at day 35. In pigs, implantation of a reduction stent graft into the circumflex artery led to complete occlusion at day 28. At this time point, retroinfusion of rAAV.VEGF-A (1 x 10(13) particles), rAAV.VEGF-A/PDGF-B (2 x 10(12) and 4 x 10(12) particles, respectively) or mock transfection was performed. Ejection fraction and left ventricular end-diastolic pressure were assessed at days 28 and 56.


RESULTS
In rabbits, rAAV.VEGF-A strongly induced angiogenesis (capillary-to-muscle fiber ratio; 1.67 +/- 0.09 vs. 1.32 +/- 0.11 in rAAV.LacZ-treated limbs, p < 0.05), but not collateral growth (125 +/- 7% vs. 106 +/- 7%, p = NS) or perfusion (136 +/- 12% vs. 107 +/- 9%, p = NS). With VEGF-A/PDGF-B cotransfection, collateral growth increased to 146 +/- 9%, perfusion to 163 +/- 8% of the respective day 7 value (p < 0.05). In the pig model, retroinfusion of rAAV.VEGF-A/PDGF-B increased regional myocardial blood flow reserve from 101 +/- 4% (rAAV.Mock) to 129 +/- 8% (p < 0.05), based on collateral growth (3.2 +/- 0.3 in rAAV.Mock vs. 9.0 +/- 0.4 in rAAV.VEGF-A/PDGF-B, p < 0.05), whereas rAAV.VEGF-A did not alter flow reserve (112 +/- 7%) or collateral count (5.2 +/- 0.7). rAAV.VEGF-A/PDGF-B improved ejection fraction (55 +/- 5% vs. 34 +/- 3% in rAAV.Mock, p < 0.05) unlike rAAV.VEGF-A (37 +/- 2%).


CONCLUSIONS
Retroinfusion of rAAV.VEGF-A alone induces angiogenesis, but fails to enhance collateralization and perfusion, unless PDGF-B is cotransfected. In addition to neovascularization, rAAV.VEGF-A/PDGF-B improves regional and global myocardial function in hibernating myocardium.
Kupatt
Christian
C
Medizinische Klinik I, Klinikum Grosshadern, Ludwig-Maximilians University of Munich, 81377 Munich, Germany. Christian.Kupatt@med.uni-muenchen.de
Hinkel
Rabea
R
Pfosser
Achim
A
El-Aouni
Chiraz
C
Wuchrer
Alexander
A
Fritz
Andrea
A
Globisch
Franziska
F
Thormann
Michael
M
Horstkotte
Jan
J
Lebherz
Corinna
C
Thein
Eckart
E
Banfi
Andrea
A
Boekstegers
Peter
P
D000818:Animals; D001808:Blood Vessels / Q000473:pathology*; D000229:Dependovirus / Q000378:metabolism*; D018014:Gene Transfer Techniques; D005821:Genetic Techniques; D015316:Genetic Therapy / Q000379:methods*; D005822:Genetic Vectors; D007511:Ischemia / Q000628:therapy*; D009206:Myocardium / Q000473:pathology*; D018919:Neovascularization, Physiologic; D020574:Proto-Oncogene Proteins c-sis / Q000235:genetics* / Q000627:therapeutic use; D011817:Rabbits; D013552:Swine; D014162:Transfection; D042461:Vascular Endothelial Growth Factor A / Q000235:genetics* / Q000627:therapeutic use
D020574:Proto-Oncogene Proteins c-sis; D042461:Vascular Endothelial Growth Factor A