Endoscopically Applied Biodegradable Stent in a Rabbit Model of Pediatric Tracheomalacia

Abstract

Objectives A polydioxanone (PDO) stent was developed to treat tracheomalacia in pediatric patients. However, its safety and efficacy need to be verified in animal studies before clinical trials in patients can be conducted. This study evaluated the safety and efficacy of a PDO stent in normal and tracheomalacia-model rabbits. Methods In total, 29 New Zealand white rabbits were used: 13 for evaluating the biocompatibility of the PDO stent in normal rabbits and 16 for the creation of a tracheomalacia model. The tracheomalacia model was successfully established in 12 rabbits, and PDO stents were placed in eight of those rabbits. Results The PDO stent was successfully positioned in the trachea of the normal rabbits using an endoscopic approach, and its degradation was observed 10 weeks later. The stent fragments did not induce distal airway obstruction or damage, and the mucosal changes that occurred after stent placement were reversed after degradation. The same procedure was performed on the tracheomalacia-model rabbits. The survival duration of the tracheomalacia rabbits with and without stents was 49.0±6.8 and 1.0±0.8 days, respectively. Thus, the PDO stent yielded a significant survival gain (P=0.001). In the tracheomalacia rabbits, stent degradation and granulation tissue were observed 7 weeks after placement, leading to airway collapse and death. Conclusion We successfully developed a PDO stent and an endoscopic guide placement system. The degradation time of the stent was around 10 weeks in normal rabbits, and its degradation was accelerated in the tracheomalacia model. The mucosal changes associated with PDO stent placement were reversible. Placement of the PDO stent prolonged survival in tracheomalacia-model rabbits.

Keywords

• tracheomalacia
• therapeutics
• trachea
• stents
• absorbable implants
• polydioxanone
• pediatrics