Biological coating for arterial stents: the next evolutionary change in stents

To describe the in vivo results of a promising new stent-graft lined with peritoneum.

Eighteen dogs underwent balloon angioplasty injury to the bilateral iliac arteries followed by placement of either an 8-mm x 5-cm glutaraldehyde-fixed bovine peritoneum- lined balloon-expandable stent (PLS) or a similarly sized, commercially prepared, polyester-lined self-expanding stent (DLS) as a control. Animals were sacrificed at 1 and 6 months. Biplanar arteriography and intravascular ultrasound were done at the time of sacrifice, and the vessels were harvested after perfusion fixation for histology/morphometry. Immunofluorescence with CD34 and factor VIII staining was used to evaluate endothelialization, while alpha-actin was used to quantify smooth muscle cell (SMC) deposition.

At 1 month, all vessels were patent in both groups. At 6 months, 8 of 9 vessels were open in the PLS group versus 6 of 9 in the control DLS group. Vessel lumen diameter at 1 month was significantly greater in the PLS vessels compared to the DLS group at 1 cm above the stent (35.9 +/- 4.4 versus 29.4 +/- 4.7 mm2; p = 0.02) and 1 cm below the stent (37.2 +/- 7.1 versus 25.2 +/- 3.2 mm2; p = 0.005); these results persisted to 6 months. Histological morphometry demonstrated progression of neointimal hyperplasia in the DLS stent between 30 and 180 days (8.3 +/- 1.79 versus 14.9 +/- 6.6 mm2; p = 0.03), whereas the peritoneum-lined stent had no change during the same time period (4.62 +/- 0.98 versus 4.72 +/- 0.97 mm2; p = 0.85). The same patterns were true for the intima:media ratio. Immunohistochemistry demonstrated complete endothelialization at 6 months in both DLS and PLS. However, SMC staining with alpha-actin demonstrated more smooth muscle actin-positive cells in the DLS compared to the PLS (327 +/- 87 versus 262 +/- 73 counts/5 high-powered fields; p = 0.04).

Peritoneum-lined stents offer a novel method to improve patency of lower extremity arterial stents.