Anat Weisz

Angiogenesis by gene therapy: a new horizon for myocardial revascularization?

The concept of therapeutic angiogenesis is based on the premise that the potential for vascular growth inherent in vascular tissue can be utilized to promote the development of new blood vessels under the influence of the appropriate growth factors. Direct application of growth factors of the fibroblast (acidic, basic fibroblast growth factor, FGF-5), endothelial (vascular endothelial growth factor) and other series has been effective in preliminary studies. Angiogenesis by gene transfer provides an attractive alternative, with the advantage that the protein may continue to be secreted for a longer period of time and that the gene may be targeted to specific tissues to enhance efficacy and reduce systemic side effects. Angiogenesis by gene transfer is currently under investigation using a variety of growth factors and a wide array of potential delivery systems. These include application of the gene as naked DNA or by viral vector in the proximal vessel by direct intravascular injection, interventional cardiologic techniques (hydrogel coating on balloon, double balloon system, stent implantation) or by direct application to adventitia, pericardium or ischemic tissue distal to the site of arterial obstruction. As our understanding of the molecular and genetic processes underlying angiogenesis increases, and as we examine the results of preliminary animal and human protocols, we hope to develop the potential of angiogenesis by gene transfer for therapeutic use.

Increased Vascular Endothelial Growth Factor 165 Binding to Kinase Insert Domain–Containing Receptor After Infection of Human Endothelial Cells by Recombinant Adenovirus Encoding the Vegf165 Gene

BackgroundThe angiogenic effect of vascular endothelial growth factor (VEGF165) is mediated mainly through the high-affinity tyrosine kinase receptor VEGF-R2 (KDR/ flk-1). This study examined the effects of VEGF overexpression by primary human endothelial cells (ECs), which do not express VEGF under physiological conditions, on cell proliferation, VEGF binding to the kinase insert domain-containing receptor (KDR), and KDR expression. Methods and ResultsHuman primary ECs and SMCs were infected by recombinant adenoviral vector encoding VEGF165 (rAdVEGF). Proliferation rate, bromodeoxyuridine incorporation, 125I-labeled VEGF165 binding to the KDR receptor, and KDR expression were tested in the infected cells and in cells supplemented with VEGF protein. Enhanced proliferation and a significant increase in 125I-VEGF165 binding to the KDR receptor were induced by rAdVEGF infection of ECs (autocrine effect) as well as by addition of recombinant VEGF165 to noninfected cells. Infection of ECs by rAdVEGF led to posttranscriptional upregulation of the KDR receptor, whereas KDR mRNA expression levels remained unchanged. Similar effects were observed with supplemented recombinant VEGF165 to noninfected ECs; nevertheless, this phenomenon occurred only with high VEGF165 concentrations (10 ng/mL). ConclusionsThe effect of VEGF165 on proliferation and upregulation of KDR receptor expression demonstrated an autocrine phenomenon of EC sensitization. The fact that high concentrations of VEGF may be achieved in vivo by local continuous overexpression of VEGF165 by gene transfer emphasizes the potential advantage of gene transfer over protein supplementation for therapeutic angiogenesis.