. To determine the role of gene therapy in preventing and/or treating intimal hyperplasia (IH) developing after angioplasty or arterial bypass surgery.
. To examine the effects of replication-deficient adenovirus vector (Ad-v) and biologically active peptides (AP) alone or in combination a) to accelerate reendothelialization at the vascular injury site (Ad-v mediated transfer of vascular endothelial growth factor and platelet-derived endothelial cell growth factor cDNA), b) to inhibit the binding of specific growth factors to their receptors (Ad-v mediated transfer of antisense to insulin-like growth factor receptor type 1, AP analogue of IGF-1 and bFGF) on vascular smooth muscle cells (VSMC), c) to induce VSMC failure to progress through the cell cycle (Ad-v mediated transfer of wild-type p53 cDNA) and d) to induce VSMC failure to migrate from the media to the intima (Ad-v mediated transfer of tissue inhibitor of metalloproteinases type 2).
The biologic effects of Ad vectors and APs will first be assessed in tissue culture experiments. The Ad-vs and APs with the expected biologic effect in vitro will then be tested in the rat carotid artery injury model of IH. In these studies Ad-vs will be delivered in the lumen of the carotid artery at the time of endothelial denudation, while APs (that require a prolonged time of action) will be administered sistemically via an osmotic pump placed subcutaneously. These experiments will determine those Ad-vs and APs most effective in preventing IH without causing significant side effects. A third group of rats will be similarly treated with a combination of the most active Ad-v and AP to demonstrate or exclude any additive or synergistic effect in the final phase of our study the Ad-v and the AP which appear most promising for clinical investigation will be tested alone or in combination in 2 minipig models of IH. In the first model (angioplasty) the Ad-v will be administered by a double balloon catheter positioned at the iliac angioplasty site, while sustained local release of the AP will be achieved by placing an AP-coated stent at the iliac angioplasty site. In the second model (bypass) the Ad-v will be instilled in an explanted saphenous vein segment that will then be anastomosed to one of the pig's carotid artery. The AP will be coated into a stent that will be deployed ex-vivo in a similarly prepared saphenous vein which will similarly be anastomosed to the carotid artery. If the experiments with the rat carotid injury model suggest that the combination of the most effective Ad-v and AP has an additive or synergistic effect, a third group of minipig will be treated both with the Ad-v and the APcoated stent in both types of model.
The extent of IH in all in vivo experiments will be assessed at different time points after the initial procedure by measuring the following parameters: a) neointimal area, b) total artery wall area, c) intima/media thickness ratio. The presence of Ad-v infection will be assessed by galactosidase activity after X-gal staining and transgene expression by Northern analysis.
Funding SchemeCSC - Cost-sharing contracts
00040 Pomezia Roma
BS2 8HW Bristol