Experimental Study On Allotransplantation Of Cryopreserved Tracheal Grafts

Tracheal transplantation is considered to be the most ideal technique for reconstruction of tracheal defect after extensive resection. Before clinical application of cryopreserved tracheal allotransplantation, tracheal transplantation must be trapped with some problems, such as preservation of tracheal graft, immunological rejection and regeneration of tracheal cartilage. Since the trachea has antigenicity, like other organs, the fresh allografts will fail due to rejection. But immunosuppressive therapy is undesirable for many reasons, especially the principal need for tracheal replacement is malignancy. Nowadays cryopreserved transplantation of some tissues such as cardiac valve, vein, skin, pancreatic island, cartilage, ovary, pituitary gland, has been successfully used in clinic.Trachea is an organ with several tissues. The cryopreserved method has different effect on the tissues. It is very important to understand the effect of cryopreserved method on the epithelium, cartilage of trachea grafts and the effect on the immunological rejection of trachea transplaintation. We also implant human bonemorphogenetic protein-2 (rhBMP-2) with collagen into the cryopreserved tracheal allografts, trying to counteract the cartilage damage. In this way we intend to make a contribution to their physiological structure and functionObjective: To investigate the the effect of cryopreserved preserved technique on the epithelium, cartilage of trachea grafts, the T-cell and mononuclear cells infiltration. To investigate the effect of cryopreserved preserved allotransplantation on the infiltration cells positive for CD3, and the possibility of the clinical application of cryopreserved tracheal allotransplantation without immunodepressant. To confirm the validity and potential application of implanting the recombinant human bone morphogenetic protein-2 (rhBMP-2) with collagen into the cryopreserved tracheal allografts to induce regeneration of dog's tracheal cartilage.Methods: (1) Each graft consisted of a 5-ring segment of the trachea harvested from inbred SD rats, then the grafts were implanted into the omentum of inbred wister rats. Forty-eight tracheal segments were randomly assigned to 8 groups according to whether with cryopreservation or not and harvesting time. The grafts were harvested at postoperation 1, 4, 8, 12weeks respectively. The tracheal segments were then evaluated grossly and histologically. The condition of epithelium and cartilage and the T-cell and mononuclear cell infiltration were graded semiquantitatively. We also detected the infiltration cells positive for CD3 with the immunohistochemical method. (2) Thirty two mongrel dogs were randomly and equally divided into 4 groups. Five ring cervical tracheal segment was harvested as the alloraft. All the grafts were wrapped with pedicled omentum. In group A, RhBMP-2 with collagen as a carrier being injected into the soft tissues between cartilaginous rings of the grafts named group Al. The blank group named group A2. In group B, before the operation the grafts were cryopreserved for two months. Just like group A, it was divide into group Bl and group B2. The animals were sacrificed...