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Vascular endothelial growth factor A (VEGF-A) induces strong angiogenesis and it has been widely used in proangiogenic gene therapy studies. However, little is known about long-term effects of VEGF-A expression in skeletal muscle. Here the long- term effects of adeno-associated virus (AAV) encoding human VEGF-A165 (AAV-VEGF-A) gene transfer in normal and ischemic rabbit hindlimb skeletal muscles were studied. AAV-LacZ was used as a control. In one-year follow-up, a remarkable increase in skeletal muscle perfusion compared with AAV-LacZ was observed measured with Doppler and contrast pulse sequence ultrasound. Angiogenesis was also seen in histology as enlarged and sprouting capillaries. In addition to favorable angiogenic effects, aberrant vascular structures with CD31 positive cell layers were seen inside muscle fibers after AAV-VEGF-A gene transfer. Importantly, we found increased amounts of extracellular matrix with a high number of macrophages and fibrosis in AAV-VEGF-A transduced muscles. No changes in skeletal muscle morphology were detected in AAV-LacZ transduced muscles. Our results indicate that local AAV-VEGF-A gene transfer efficiently promotes long-term angiogenesis in large animal model. However, non-regulated expression of VEGF-A causes unfavorable changes in muscle morphology, which suggests the need for regulation of the transgene expression in long-term AAV-mediated VEGF-A gene transfer applications. [ABSTRACT FROM AUTHOR]

Aims: The aim of this study was to determine dose–response effects of vascular endothelial growth factor A as delivered using an adenoviral vector on vascular growth and pathological changes in the rabbit eye. Moreover, we wanted to develop a large animal model for angioproliferative diseases in the eye. Methods: Seventeen New Zealand White rabbits were injected with adenoviral vascular endothelial growth factor-A (AdVEGF-A) intravitreally with different doses (109–1011 vp). Controls were injected with an empty virus (AdCMV). Some animals had a combination of AdVEGF-A and AdsKDR (a soluble form of the VEGF receptor-2). Animals were killed 6 days after the gene transfer. On the basis of these results, 14 rabbits were injected intravitreally with AdVEGF-A or adenoviral LacZ (AdLacZ) with 1010 vp in a volume of 0.1 mL. Animals were killed 3, 6, 14 and 28 days after the gene transfer, eyes were removed and analysed histologically. Results: In enzyme-linked immunosorbent assay (ELISA) analysis, human VEGF-A was present in vitreous humour in all VEGF-A transduced eyes. The amount of VEGF-A showed a dose-dependent increase with the AdVEGF-A dose and was the highest 6 days after the gene transfer. Histologic analyses revealed an increased capillary area and density in the AdVEGF-A eyes when compared with the AdLacZ eyes ( P < 0.05). In the AdVEGF-A/AdsKDR eyes the average capillary area was not increased compared with AdLacZ eyes. Conclusion: This model could be useful for large animal studies regarding the pathogenesis of neoangiogenesis and for the development of new therapeutic strategies for angioproliferative diseases of the eye. Our results establish the key role of VEGF-A in the induction of neovascularization and pathological changes in the rabbit eye. [ABSTRACT FROM AUTHOR]

Gene transfer to the vessel wall using vascular endothelial growth factors (VEGFs) has shown therapeutic potential for the treatment of restenosis. In this study, we evaluated the effect of catheter-mediated adenoviral (Ad) gene transfer of the mature form of VEGF-D (VEGF-DΔNΔC) in balloon-denuded cholesterol-fed rabbit aorta. AdLacZ was used as a control. Transduced VEGF-DΔNΔC mRNA was detectable in the arterial wall with RT-PCR at 6, 14 and 28 days. Gene transfer efficiency as detected with X-gal staining 6 days after the AdLacZ transduction was 1.91±1.32% in intima. AdVEGF-DΔNΔC gene transfer led to 52% reduction in intima/media ratio (I/M) as compared to the AdLacZ controls at 14 days time point. At 6 days there were no differences in I/M, but the number of macrophages in the vessel wall was 85% lower in the AdVEGF-DΔNΔC group as compared to the controls. The therapeutic effect was no longer detectable 28 days after the gene transfer. The therapeutic effect of VEGF-DΔNΔC was nitric oxide (NO)-dependent as the feeding of NO synthase inhibitor, L-NAME, blocked the reduction in intimal thickening. It is concluded that AdVEGF-DΔNΔC gene transfer reduces intimal thickening and macrophage influx into the vessel wall in balloon-denuded rabbit aortas.Gene Therapy (2005) 12, 980–987. doi:10.1038/sj.gt.3302489 Published online 10 March 2005 [ABSTRACT FROM AUTHOR]