Gene therapy in vascular surgery comes of age

Vascular endothelial growth factor - basic science and its clinical implications

Vascular endothelial growth factor (VEGF) is the most important signaling molecule involved in the regulation of the formation of new vessels. Results of recent studies have provided new insights into the molecular mechanisms of the VEGF signaling pathways. VEGF local or systemic application represents a new approach in the therapy of ischemic diseases, especially of the coronary artery disease. Inhibition of the VEGF action on various levels is, on the other hand, assumed to be a promising therapeutic concept against cancer. Moreover, VEGF has been recently shown to be associated with some other physiological and pathophysiological processes. In this article we summarize the latest results of VEGF related studies and present the concluding theoretical resource for further research on the role of VEGF in understanding of pathophysiology of diseases and in therapeutic interventions in clinical biomedicine.

Intramuscular gene transfer of FGF-2 attenuates endothelial dysfunction and inhibits intimal hyperplasia of vein grafts in poor-runoff limbs of rabbit

We previously demonstrated that sustained disturbance of endothelium-dependent vasorelaxation and poor distal runoff in ischemic limbs were critical factors affecting the neointimal development of autologous vein grafts (VGs). Also, we recently showed the superior therapeutic potential of basic fibroblast growth factor (bFGF/FGF-2) boosted by the recombinant Sendai virus (SeV) for severe limb ischemia compared with that of vascular endothelial growth factor. Here, the effect of FGF-2 on neointimal hyperplasia of VGs was examined in a rabbit model of poor-runoff limbs. Two weeks after initial surgery for the induction of poor-runoff, SeV-expressing human FGF-2 (SeV-hFGF2) or that encoding firefly luciferase (109 plaque-forming units/head) was injected into the thigh and calf muscle. At that time, the femoral vein was implanted in the femoral artery in an end-to-end manner in some groups. FGF-2 gene-transferred limbs demonstrated significantly increased blood flow assessed not only by laser Doppler flow image but also by ultrasonic transit-time flowmeter (USTF). USTF also showed a significant increase in the blood flow ratio of the deep femoral artery to external iliac artery, indicating that collateral flow was significantly restored in the thigh muscles (P < 0.01). Reduction of neointimal hyperplasia was also observed in the VGs treated by SeV-hFGF2; these grafts demonstrated significant restoration of endothelium-dependent vasorelaxation. These findings thus extend the indications of therapeutic angiogenesis using SeV-hFGF2 to include not only limb salvage but also prevention of late graft failure.

Clinical trials of gene therapy for atherosclerotic cardiovascular disease

PURPOSE OF REVIEW

To provide an update on clinical trials of gene therapy for atherosclerotic cardiovascular disease published since 1 August 2001 and summarize the general advantages and potential problems of gene transfer in these disorders.

RECENT FINDINGS

There are two major areas in which gene therapy has entered clinical trials. The first is angiogenesis for coronary and peripheral arterial disease. Two relatively small placebo-controlled trials for coronary disease were reported, one using intramyocardial plasmid VEGF-2 gene, the other using intracoronary adenoviral FGF-4 gene. The VEGF-2 study in no-option patients showed reduced angina, and significant improvement in perfusion and function, whereas the FGF-4 study in less severely affected patients showed promising results in some subsets. In peripheral artery disease two phase 1 studies of adenoviral NV1FGF and VEGF showed some objective improvement in pain, ulcer size and ankle:brachial index in one study and endothelial function in the other. Both adenoviral and plasmid VEGF gene transfer at angioplasty increased vascularity in a phase 2 double-blind study. The other major area is the prevention of graft disease and restenosis using antisense oligodeoxynucleotides. E2F decoy led to a significant reduction in venous graft complications after ex-vivo transfection at the time of coronary bypass surgery, whereas the c-Myc oligodeoxynucleotide was ineffective in preventing in-stent coronary restenosis.

SUMMARY

There are more reviews of gene therapy for atherosclerosis in the literature than publications with original data or trials, but in the past year the imbalance is being redressed, with some promising results from controlled studies.