Preclinical Evaluation of a Pediatric Airway Stent for Tracheobronchomalacia

Abstract Objectives We sought to demonstrate in an animal model that helical NiTi stents designed for malacic airways could be delivered and removed without significant trauma while minimally impeding mucus clearance during the period of implantation. Methods Stents were delivered and removed from the tracheas of healthy 20 kg swine (n=5) using tools designed to minimize trauma. In 4-week experiments, the stents were implanted on day 0, removed after 3 weeks and euthanasia was performed after 4 weeks. Weekly bronchoscopies, X-rays and mucus clearance examinations were performed in vivo. Hematoxylin and eosin (H&E) staining and scanning electron microscopy (SEM) imaging were used to evaluate foreign body response, tracheal tissue reaction and damage and to measure non-ciliated regions. Results In all in vivo experiments, the stent was implanted and removed atraumatically. Mucus clearance was maintained throughout the experiment period. H&E stained slides showed that foreign body response and tracheal tissue damage were localized to the stented subsections. Tracheal tissue reaction and damage was further restricted to the epithelium and submucosal layers. SEM imaging revealed that the cilia was absent only over the contact area between the trachea and the wire forming the helical stent. Conclusions Helical NiTi stents designed to provide radial support for malacic airways were well tolerated in a porcine model, providing for mucus clearance while also enabling atraumatic removal.