The sealing effect and degradation of polydioxanone weaving tracheal stents in a canine airway defect model.

Abstract

The use of covered self-expandable metal (CSEM) stents for fistulas sealing is a common clinical approach. However, these stents need to be removed once their therapeutic goals are achieved. Our study designed and fabricated a dumbbell-shaped, high-porosity, biodegradable polydioxanone weaving tracheal (PW) stent, and investigated its sealing efficacy and degradation characteristics. A tracheal defect model was created in 24 beagle dogs. Six dogs were implanted with CSEM stents, while the remaining 18 dogs received PW stents. The dogs in the CSEM and PW groups were observed for up to 8 and 14 weeks, respectively, with clinical symptoms, tracheoscopy, computed tomography scans, and fluoroscopy monitored. Subsequently, the stents were retrieved to observe morphological changes, and measure mechanical properties. The PW stents exhibited excellent airtightness, with significantly fewer complications such as stent displacement and granulation tissue hyperplasia compared to the CSEM stents. The tracheal tissue response to the PW stent was relatively mild. After PW stent implantation, collagen fiber deposition at the defect site gradually increased, and cartilage structure regeneration was observed in later stages. Notably, cilia were largely absent in the tracheal epithelium, with squamous metaplasia observed even in the later stages of the experiment following PW stent implantation. Additionally, the PW stents remained mostly intact in the canine airways until week 12, and were completely degraded and disappeared from the canine airways at week 14, without causing severe complications. The PW stent, featuring excellent biocompatibility and uniform degradation in the large-animal airway, demonstrated clinical effectiveness in sealing tracheal defects.