Long-term cryopreservation can prevent rejection of canine tracheal allografts with preservation of graft viability

Abstract

We previously reported that cryopreservation of tracheas for 1 month was possible in a canine tracheal autotransplantation model with use of a preservative solution containing trehalose. Realizing that the allogenicity of many organs is decreased by freezing, we examined the possibility of immunosuppressant-free canine tracheal allotransplantation after long-term cryopreservation. Six to 10 rings of the trachea were removed from donor dogs (n = 12), immersed in the preservative solution, and cryopreserved in a deep freezer at -85 degrees C for 285 +/- 28 days (cryopreservation group). Five rings of the mediastinal trachea of recipient dogs were removed. The cryopreserved tracheas were thawed and transplanted to replace the excised mediastinal tracheas. In a control group (n = 6), the graft was preserved in Euro-Collins solution at 10 degrees C for 16 to 17 hours. Allotransplantation of tracheas was done as in the cryopreservation group. The anastomotic site and graft were covered with an omental pedicle in both groups. In the cryopreservation group, every animal, except one that was killed for pathologic examination, survived more than 2 months. All the grafts of this group were viable, and no stenosis or tracheomalacia was observed. In the control group, most of the animals died within 1 month of tracheal stenosis caused by rejection. These findings reveal that immunosuppressant-free canine tracheal allotransplantation was consistently possible after long-term cryopreservation of the graft in a preservative solution containing trehalose. This simple method could solve both donor shortage and immunosuppression problems.

Heterotopic transplantation of glycerin-preserved trachea: effect of respiratory epithelium desquamation on acute rejection

“…On the basis of the present results, we suggest that the lower antigenic stimulation by glycerin-preserved tracheal allografts, as also reported in cryopreservation studies (3,6,13), may result from the denudation of native epithelium, with reduction and maybe absence of MHC class II antigens.…”

Effects of cryopreservation on tracheal allograft antigenicity in dogs

“…Although some data suggest a decline in allograft antigenicity by doing so, thus raising hopes of immunosuppressant-free transplantation (and eliminating side effects, costs) (5-7), there is also evidence to the contrary (8)(9)(10)(11). Yokomise and colleagues successfully conducted tracheal allotransplantation in dogs, without use of immunosuppressants, by immersing grafts in a cryopreservative solution and deep freezing (−85 ℃) for 285±28 days (~8-10 months) (12). Aside from one animal sacrificed for histologic study, the canine recipients of such transplants survived for more than 2 months.…”

“…Thus, reduced antigenicity was considered the basis for the benefits derived in tracheal allografts (12). However, it was unclear how the above specified period of cryopreservation was selected, raising further issues on how prolonged cryopreservation actually alters the tracheal epithelium or what duration of storage is required to fully denude m u c o s a f o r t r a n s p l a n t a t i o n w i t h i m p u n i t y ( i .…”

Tracheal Tissue Engineering

“…Cryopreserved allografts with omental flap revascularization survived without immunosuppressive therapy [124,125,129]. Mukaida observed gradual replacement of graft epithelium by recipient epithelial cells after sixty days in a cryopreserved tracheal allograft [130].…”