Plastic Surgery Research Council
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DETERMINING THE IN VITRO AND IN VIVO IMMUNE RESPONSE TOWARDS DECELLULARIZED AND RECELLULARIZED PORCINE TRACHEAL ALLOGRAFTS FOR AIRWAY TRANSPLANTATION
Presenter: Siba Haykal, BSc, MD, Phd Candidate, Resident
Co-Authors: Zhou Y; Marcus P; Salna M; Machuca T; Hofer SO; Waddell TK
University of Toronto

Introduction: Malignancy, subglottic stenosis and traumatic injury to the trachea require surgical resection. The advances in airway allotransplantation focused on tracheal decellularization techniques which allow for removal of the immunogenic components. Despite the multiple advances in this field, the local and systemic immune response to these decellularized tracheal segments has not been explored in depth.

Materials and Methods: Tracheae were harvested from Yorkshire pigs (n=6) and decellularized using three different decellularization protocols. Tracheae were evaluated histologically and by immunostaining for MHCI and MHCII markers. CFSE labelling in a Mixed Lymphocyte Reaction (MLR) type assay was used to assess CD4+ and CD8+ T cell proliferation following incubation with tracheal pieces. Recipient specific mesenchymal stromal cells (rMSCs) and tracheal epithelial cells (rTECs) were also harvested and co-cultured in the MLR. Native and decellularized tracheal allografts were heterotopically transplanted and tracheal segments were biopsied each week for 3 weeks for histology, immunohistochemistry, PCR and flow cytometry looking at infiltrating cells.

Results: Following decellularization, cells within the glands continue to stain for anti-MHCI and anti-MHCII. T cells continued to proliferate on tracheal pieces in an MLR. CD4+ T cell proliferation was reduced on Protocol B pieces co-cultured with rMSCs and rTECs. In vivo heterotopic transplantation revealed a delay in leukocyte infiltration following decellularization and an increase in CD4+ CD25+ Foxp3+ T cells.

Conclusions: Decellularized tracheal segments appear to elicit a different immune response both in vitro and in vivo compared to native segments. Decellularization delays leukocyte infiltration and results in subtle changes in the type of cells recruited but they ultimately undergo degradation associated with infiltration.


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