Abstract 247: Therapeutic Neovascularization by AAV2/9 Based Gene Transfer of hVEGF-A and hPDGF in Chronic Ischemia (rabbit model)
Therapeutic neovascularization by several growth factors is a concept well established in multiple animal models, albeit lacking clearcut clinical success to date. Therefore, we modified our therapeutic approach by combining the potent angiogenic agent hVEGF-A with hPDGF, a growth factor known for attracting pericytes and smooth muscle cells for arterial vessel maturation. In order to enhance efficacy, we utilized adeno-associated virus (AAV) 2/9, allowing for prolonged transgene expression. A lower hVEGF-AAV-concentration was used to avoid hemangiomaformation. 7 days after femoral artery excision, 1×10e11 hVEGF-A-AAV alone or in combination with 1×10e12 hPDGF-AAV particles were retroinfused into the anterior tibial vein of rabbits (n=5/group, p<0.05). LacZ-AAV2 was used as reporter-gene controls. At d7 and 35 angiography of both hindlimbs was performed for collateral quantification (% of d7 level) and frame count score (cinedensitometry, % of d7 level). Capillary density (Capillary muscle fiber ratio, CM/F) was assessed at d35 by PECAM-1 and alkaline-phosphatase-staining of the ischemic gastrocnemic and tibial anterior muscles, pericyte-quantification was assessed by NG2-staining. LacZ-expression was detected at d35 in control animals. hVEGF-A-AAV retroinfusion strongly induced angiogenesis (CM/F 1,32+0,07 vs. 0.96+0,08, controls), but failed to enhance collateral growth (125+7 vs. 95+6%, controls, p<0.05) or perfusion (frame count score: 136+12% vs. 107+9%, p=0.07). hVEGF-A/hPDGF co-application, however, enhanced perfusion (163+8%, p<0.05) via an increased collateral growth (146+9%, p<0.01) at a similar capillary density (1,44+0,10). We conclude, that efficacy of hVEGF-A-transfection is increased by hPDGF-co-transfection with a long-acting AAV. Utilizing this approach, the main target of hPDGF appears to be the collateral vasculature, complementary to the capillary growth induced by hVEGF-A. Thus, the combination of hVEGF-A and hPDGF combined with a long-acting AAV-vector is a promising tool in the quest of efficient therapeutic neovascularization.