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

Purpose: To describe the in vivo results of a promising new stent-graft lined with peritoneum. Methods: Eighteen dogs underwent balloon angioplasty injury to the bilateral iliac arteries followed by placement of either an 8-mm × 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 α-actin was used to quantify smooth muscle cell (SMC) deposition. Results: 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 α-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). Conclusion: Peritoneum-lined stents offer a novel method to improve patency of lower extremity arterial stents.