Unveiling Immune Responses in the Trachea Following Scaffold Implantation in a Mouse Model.

Objectives: Tracheal stenosis with long lesions poses a challenge for surgical treatment, requiring a bioengineering approach. However, synthetic tracheal scaffolds often fail due to the host immune response against the implant. Nonetheless, the key immune cells in the tracheal environment and their interactions against scaffolds remain poorly understood. In this study, we examined the tracheal immune cell compositions and their dynamics in response to the scaffold implantation.

Methods: We used C57BL/6 mice to develop a model for identifying immune cells. For the scaffold implantation, a circumferential tracheal defect was made, and a poly(ε-caprolactone) (PCL) scaffold was orthotopically implanted. Tracheal cells were isolated using an enzyme digestion protocol, and immune cells and their subsets were identified by flow cytometry on days 1 and 7 post-implantation.

Results: A circumferential tracheal defect was successfully created in mice, followed by the implantation of a PCL scaffold. Viable immune cells were consistently isolated from the trachea. Diverse populations of innate and adaptive immune cells were recovered, with CD3-B220-myeloid cells constituting the predominant population in normal mouse trachea. Importantly, implantation of the PCL scaffold severely disrupted local immune homeostasis, inducing a strong CD8α^- T cell response, reaching approximately 65% of total immune cells on postoperative day 1.

Conclusion: We present findings on immune responses in the trachea, highlighting the immune cells involved in maintaining homeostasis and their disruption following scaffold implantation. These insights could support the development of targeted immunomodulation strategies, thereby improving the integration and clinical application of biomaterials in tracheal reconstruction.

Level of evidence: NA.