Cryopreservation of the tracheal grafts: Review and perspective

Abstract

Transplantation of the trachea may become the preferred method for the reconstruction of extensive tracheal defects, however, several unresolved problems must be addressed, such as immunosuppression, preservation and donor shortage. In this manuscript, the cryopreservation of tracheal grafts is reviewed, which potentially is associated with a lessened immunological response. Cryopreservation may be used clinically for long-term preservation and may solve the donor shortage. It is very important to confirm the immunomodulatory effect of cryopreservation on tracheal allografts in order to expand the potential clinical application of tracheal transplantation in the future. The cartilage as well as the epithelium and lamina propria serve as targets for rejection. However, the effect of cryopreservation on chondrocytes could be associated with reduced allogenicity of the trachea. The long-term cryopreservation of cartilage must be investigated in basic research models of chondrocyte viability. Growth of cryopreserved tracheal allografts is less well understood. Further studies are needed to elucidate the mechanism of synergistic effects of both cryopreservation and adequate immunosuppression for tracheal xenografts.

Keywords: airway; allograft; animal model; cryopreservation; homograft; isograft; trachea; transplantation; xenograft.

Figure 1

Histologic findings of cryopreserved rat tracheal allograft immediately after thawing. The epithelium shows degeneration but not denuded. (Hematoxylin and eosin; original magnification, ×200).

Figure 2

Histologic findings of fresh rat tracheal allograft 3 months after transplantation, which was denuded of the epithelium. The graft shows narrowed patency because of thickened mucosa with mononuclear cell infiltration. (Hematoxylin and eosin; original magnification, ×25).

Figure 3

Histologic findings of rat tracheal allografts 28 days after transplantation. (A) a second allograft after transplantation of fresh allograft. The allograft is severely rejected. (B) a second allograft after transplantation of cryopreserved allograft. The patency of the allograft is narrow but the structure is maintained. (Hematoxylin and eosin; original magnification, ×25).

Figure 4

Histologic findings of cryopreserved tracheal xenograft 28 days after transplantation, which received short-course immunosuppression with 3.5 mg/kg/day of Tacrolimus. The epithelium shows degeneration but the cartilage is well maintained. (Hematoxylin and eosin; original magnification, ×200).