Bridging the gap: Using 3D printed polycaprolactone implants to reconstruct circumferential tracheal defects in rabbits

Objective: 1) To assess the feasibility of reconstructing 2-cm-long circumferential tracheal defects with a 3D printed polycaprolactone (PCL) implant in rabbits. 2) To evaluate endoscopic, histologic, and functional characteristics of a PCL tracheal implant over time.

Methods: Ten New Zealand rabbits were included in this study. A 2-cm-long 3D printed PCL tracheal implant was created. All rabbits underwent surgical excision of a 2-cm-long cm segment of cervical trachea, which was reconstructed with the implant. Rabbits were sacrificed at the following time points: 0, 4, 5, 6, and 7 weeks postoperatively. At these time points, a rigid bronchoscopy was performed, and blinded evaluators calculated the percentage of airway stenosis. The tracheas were then harvested and prepared for histologic analysis.

Results: All rabbits survived to their date of sacrifice except for one. Rabbits were euthanized between 0 to 54 days postoperatively with a median of 30 days. All rabbits developed significant granulation tissue with an average percentage stenosis of 92.3% ± 6.1%. On histology, granulation was present with extensive neovascularization and mixed inflammatory cells. There was re-epithelialization present on the luminal surface of the PCL implant near the anastomoses but absent at the center of the implant.

Conclusion: This study demonstrates that our 2-cm-long 3D printed PCL tracheal implant can be used to reconstruct a tracheal defect of equivalent size in a New Zealand rabbit model in the short term. However, significant granulation tissue formation limits long-term survival. Further research is warranted to limit the granulation tissue overgrowth.

Level of evidence: NA Laryngoscope, 2019.