Use of a composite, 3D-printed patch as a partial airway replacement: A pilot study on the porcine model.

Tracheal replacement is an unmet clinical need, as patients with long or complex airway defects are managed with tracheostomy or permanent stents. Experimental and clinical research is ongoing in order to find safe airway substitutes; however, the strategies under investigation suffer from major limitations, such as unsatisfactory re-epithelialization, insufficient long-term mechanical support, and complex ex vivo procedures. A ready-to-use and stable patch, able to support airway functionality and tissue regeneration, remains a significant challenge. Here we present the development of an off-the-shelf composite patch consisting of a resorbable polymer to aid epithelial restoration and a 3D-printed multimaterial structure to guarantee effective mechanical stability. To evaluate the prosthesis performance, we designed a pilot study on a large animal setting, monitoring postoperative survival and airway healing for up to 60 days. An anterior cervical tracheal defect was created on four domestic pigs and patched with the prosthesis. The results were satisfactory in terms of postoperative survival, as only one animal died before the end of the study. However, endoscopic findings revealed a worsening stenosis due to wound contraction, granulation tissue formation, and partial displacement of the prosthesis. These findings were confirmed at histology, where a prominent inflammatory infiltrate was evident. Blood tests performed during follow-up did not reveal any systemic inflammatory reaction. Overall, we believe that further optimization of the prosthesis design and materials is necessary in order to create an ideal "off-the-shelf" tracheal substitute. Nevertheless, this pilot study provides promising results and novel insights into a clinically relevant research area.