Vascular endothelial growth factor （VEGF） is an angiogenic regulator that stimulates endothelial cell migration, proliferation, and angiogenesis. VEGF gene therapy is a new promising approach to induce therapeutic angiogenesis for the treatment of ischemic myocardial and limb diseases. Recently, clinical studies have demonstrated successful outcomes using plasmids, retroviruses and adenoviruses.l-3 But the safety of those vectors is poor, which has become a serious concern. Besides immunogenicity caused by viral vectors, a further problem is that viral vectors show a preference to integrate into the transcription or control region of active genes, which may induce tumors and other disorders.
