Biocompatibility and performance of the Wallstent and the Wallgraft, Jostent, and Hemobahn stent-grafts in a sheep model.

PURPOSE: Three recently developed stent-grafts and the Wallstent were compared directly in an ovine animal model with regard to performance and biocompatibility. MATERIALS AND METHODS: Three stent-grafts, the Hemobahn (polytetrafluoroethylene [ePTFE]/nitinol), Wallgraft (polyester/Ni-Co-Ti-steel alloy), and Jostent peripheral stent-graft (balloon-expandable ePTFE/stainless steel), and the Wallstent (Ni-Co-Ti-steel alloy), were implanted in sheep iliac arteries (one type of each stent or stent-graft per animal, n = 8). Pre- and postimplantation luminal diameters were measured for each prosthesis and implantation site. Angiography, intravascular ultrasonography (IVUS), and histomorphometric, histologic, and scanning electron microscopic analyses were performed at 3 months. RESULTS: Early lumen gain, late lumen loss, and patent vessel diameter at angiography were not significantly different. Two stent-grafts had significantly more neointima formation (Hemobahn, 9.88 mm(2) +/- 0.94; Wallgraft, 14.98 mm(2) +/- 0.90) than the other stent-graft (Jostent, 6.52 mm(2) +/- 0.46) and the Wallstent (5.24 mm(2) +/- 0.62; P <.01). Patent lumen area was not significantly different (Hemobahn, 42.57 mm(2) +/- 1.41; Jostent, 39.76 mm(2) +/- 2.04; Wallgraft, 40.22 mm(2) +/- 1.04; Wallstent, 41.64 mm(2) +/- 1.59; P =.57). The Hemobahn had significantly more inflammatory reaction (inflammation score of 0.83 +/- 0.03) than the Jostent (0.58 +/- 0.03), Wallgraft (0.55 +/- 0.04), or Wallstent (0.16 +/- 0.01). Angiography and IVUS demonstrated absence of anastomotic neointima formation. Endothelialization was incomplete and immature for all prostheses. CONCLUSIONS: The stent-grafts caused a greater degree of neointima formation and inflammatory vessel wall reaction than the bare stent. However, these changes did not interfere with patent lumen areas and occurred in the absence of excessive anastomotic neointima formation.

Inhibition of neointimal formation after stent placement with adenovirus-mediated gene transfer of I kappa B alpha in the hypercholesterolemic rabbit model: initial results.

PURPOSE: To evaluate the feasibility and efficacy of the local application of a replication-defective adenovirus construct for the expression of the antiinflammatory protein I kappa B alpha, inhibitor of nuclear factor kappa B (NF-kappa B), to reduce neointimal formation after stent placement. MATERIALS AND METHODS: Nitinol stents were implanted in the iliac arteries of hypercholesterolemic rabbits, followed by balloon dilation (30 seconds at 6 atm). Local adenovirus-mediated transfer of I kappa B alpha (3 mL of 10(9) plaque-forming units per milliliter at 6 atm) was performed and compared with three control groups: stent alone, stent plus local delivery of phosphate-buffered saline (PBS) (3 mL at 6 atm), and stent plus local delivery of control adenovirus coding for green fluorescent protein (GFP) (3 mL of 10(9) plaque-forming units per milliliter at 6 atm). A multichannel balloon was used for local drug delivery and balloon dilation. Animals were sacrificed 1 or 4 weeks after treatment. Effective transfection was demonstrated with immunofluorescence staining. Angiographic patency and luminal diameter were evaluated at quantitative angiography. Luminal and neointimal areas were measured on surface-stained ground sections with methylmethacrylate embedding and the cutting-grinding technique. RESULTS: All vessels with stents were patent at angiography. Neointimal area was negligible in all groups 1 week after stent placement (range, 0.42-0.52 mm(2); P =.44; analysis of variance). Neointimal formation was demonstrated in all groups 4 weeks after implantation but was significantly reduced with I kappa B alpha treatment compared with treatment with stent alone (by 22%, from 2.80 mm(2) +/- 0.20 to 2.28 mm(2) +/- 0.14, P =.05), stent plus PBS (by 43%, from 3.26 mm(2) +/- 0.25 to 2.28 mm(2) +/- 0.14, P =.005), and stent plus GFP (by 53%, from 2.32 mm(2) +/- 0.19 to 1.51 mm(2) +/- 0.08, P <.005). CONCLUSION: Local adenovirus-mediated I kappa B alpha gene transfer has the potential to reduce intimal hyperplasia after stent placement.