Angiogenesis and gene therapy in man: dream or reality?

Preclinical studies indicate that angiogenic growth factors can stimulate the development of collateral arteries in animal models of peripheral or myocardial ischaemia, a concept termed 'therapeutic angiogenesis'. The goal of this review is to provide a brief overview of the advantages and disadvantages of gene versus recombinant protein therapy for therapeutic angiogenesis. We also discuss different options for delivering genes to patients, including plasmids and modified viral vectors. Recently, the safety and potential utility of gene therapy for ischaemic disease were demonstrated in 3 clinical trials involving the delivery of plasmid DNA encoding the 165 amino acid isoform of human vascular endothelial growth factor (phVEGF165), a factor that specifically promotes the proliferation and migration of vascular endothelial cells. Two trials involved the administration of phVEGF165 for peripheral arterial disease. In one trial, the plasmid was administered to the arterial wall from a hydrogel-coated angioplasty balloon, while a second trial examined the direct injection of phVEGF165 into the skeletal muscle of the affected limb. More recently, phVEGF165 was directly injected into ischaemic myocardium. In all these trials, it appears that administration of phVEGF165 led to improvements in tissue perfusion.