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DOI: 10.1055/s-0029-1191444
Aortic Xeno-transplantation for tracheal replacement: Mechanistical analysis of tissue metaplasia
Aims: Reconstruction of tracheal defects after resection still remains a challenge. Tissue metaplasia has been confirmed after tracheal replacement with allogenic aortic grafts in ovines, however the underlying mechanism of this remains unclear. In order to analyse the role of inflammation, we established, the feasibility of aortic xeno-transplantation from porcines to ovines for tracheal regeneration.
Methods: Eight female sheep underwent a 5-cm tracheal replacement with a fresh aortic xenograft from female donor pigs. Before implantation the graft was bathed for 4 hours in a heparinized saline solution to destroy the endothelium known as the main immunogenic mediator. An 8-cm silicone-stent was used to prevent airway collapse after implantation. No immunosuppressive therapy was used. Animals were sacrificed at one (n=3), three (n=3) and six (n=2) months for histopathologic analysis.
Results: All animals survived without complications and did not appear sick until sacrifice. At sacrifice the aortic graft appeared totally rejected. The surrounding tissue reaction was impressive, demonstrating complete healing and allowing for a functional airway with no anastomotic leaks or strictures. On histology at 1 month, this tissue was mainly composed of granulation tissue. At 3 month this tissue developed a suppurative exsudate overlying granulation tissue. Neo-cartilage islet formation was demonstrated within the elastic lamina of the pig-aorta in the specimems after 6 months.
Conclusions: Aortic tracheal xeno-graft replacement is feasible and survival can be achieved without any immunosuppressive therapy. These results demonstrate that the porcine xeno-graft is acutely rejected and that the increased inflammation probably contributes to tissue metaplasia.