Influence of a Paclitaxel-eluting Expandable Metallic Stent on Tissue Hyperplasia: An Experimental Study in a Canine Tracheal Model

Abstract

Purpose: To evaluate the efficacy of a paclitaxel-eluting expandable metallic stent in reducing tissue hyperplasia following stent placement in a canine tracheal model. Materials and Methods: Nine paclitaxel-eluting stents (drug stent, DS) consisting of a proximal bare part and a distal polyurethane-covered part were placed in the trachea of nine dogs and nine control stents (control stent, CS) were placed in the other nine dogs. The dogs were scheduled to be sacrificed 12 weeks after stent placement. Gross and histological factors, such as epithelial erosion/ulcer, granulation tissue thickness and inflammatory cell infiltration were evaluated after each dog was sacrificed. Results: There were no procedure-related complications or malpositioning of any of the stents. One CS migrated less than eight weeks following stent placement. Four dogs (one DS and three CS dogs) died between three and five weeks following stent placement. Therefore, pathologic specimens were obtained from eight DS and five CS dogs. Epithelial erosion/ulcer or inflammatory cell infiltration was slightly more prominent in the DS cases than in the CS cases, in both the bare part and the covered part. However, the data was not statistically significant. Granulation tissue thickness was lower in the DS cases than in the CS cases in both the bare part (mean, 3.63-mm vs. 4.37-mm) and the covered part (mean, 1.75-mm vs. 2.78 mm), but the data was also statistically insignificant. Conclusion: Although the data was not statistically significant, placement of paclitaxel-eluting expandable metallic stent demonstrates a tendency toward a decrease in granulation tissue thickness in canine tracheal models.