Study Of The Changes In Skin And Appendages In Facial Allotransplantation

Part 1.Study of the changes in skin and appendages in rabbits in hemifacial composite tissue allotransplantationObjective: To study the changes in skin and appendages in rabbits after hemifacial composite tissue allotransplantation. Methods: Sixteen Japanese white rabbits were used in this experiment and similar weight was maintained between the donor and the recipient. Carotid artery and jugular vein served as blood supply and vascular reflux for rabbit hemifacial composite tissue allograft. Tacrolimus and prednisone were administered as the immunosuppressive agents. The dosage of tacrolimus was adjusted according to the outcomes of blood concentration tests with peripheral venous blood. Pathological examination of transplant tissues was performed after 7 days, 30 days and 40 days. Results: Among the 8 cases of facial allograft, one died due to the formation of graft hematoma; one developed skin flap necrosis due to poor venous reflux; the remaining six cases survived 24 days on average, the shortest being 20 days and the longest over 40 days; and there was no case of death caused by anesthesia. Histology observations showed that at postoperative week 1, the number of skin appendages was more than that of normal, with most obvious hyperplasia in the sweat glands, normal structure of the skin appendages, and no apparent lymphocyte infiltration; and on postoperative day 30 and day 40, there was no obvious hyperplasia of skin appendages, with similar to normal structure of the skin appendages and no lymphocytic infiltration. Conclusion: 1. After hemifacial allotransplantation in rabbits,the number of skin appendages was more than that of normal. 2. Tacrolimus and prednisone were able to prevent and control the post-transplant rejection effectively. 3. Due to petite physical size, poor tolerance of transplantation, and limited immune suppression, the model of rabbits was not suitable for long-term observation of the skin appendages after allograft. Keywords: allograft, composite tissue , rabbit , skin , appendagesPart 2 Study of the changes in shin and appendages in canines in hemifacial composite tissue allotransplantationObjective: To develop an experimental model of facial composite tissue allotransplantation in canine and observe the restore situation of skin appendages for further research. Methods:â‘ Anatomic study: Three mongrel dogs were used for anatomical dissection of the head and neck region to observe the course, size and variation of arteriovenous vascular.â‘¡Methylene blue perfusion: Carotid artery with the branch of the external mandibular was dissected and then methylene blue was injected through the external mandibular artery to observe the scope of perfusion to determine the size of composite tissue flap.â‘¢Allograft transplantation: Hemifacial composite tissue allograft was performed in Beagle dogs. Cyclosporin A(Cs-A) and Prednisone(PS) were jointly used as immunosuppressive protocol. Light microscopy and electron microscopy of transplant skin were conducted at 70 days and 100days. Results: 1. (n=3) canine blood vessels of head and neck were similar to those of mankind;Unilateral carotid arteries of the canines were ligated and all of the animals survived in good condition and no fatal ischemia of the brain occurred. 2. All the composite allograft on the site of the carotid artery with the branch of the external mandibular artery survived, which supplied enough blood to the hemifacial composite flap. 3. At 4 days postoperatively, immunologic rejection occurred in one Beagle and was addressed by adjusting the dosage of cyclosporine and no rejection reoccurred. The blood supply of the flap was normal and no hair loss occurred. In the flap observation window the hair grew well. At 57 days infections appeared on the left hindlimb and at 67 days on the right hindlimb and disappeared after washing and antibiotic treatment. 4. Pathology: The optical microscopy revealed that the number of the appendages of the flap at 70 days postoperatively was more than that of the normal and the structure of the appendages was similar to that of the normal. Electric microscope showed that mitochondria of some hair follicles swelled but the structure of the mitochondria of the sweat glands and sebaceous gland cells were clear and did not swell. At 100 days postoperatively there was no abnormal appendage structure and no significant inflammatory cell infiltration. Conclusion 1.The number of hair follicles together with sebaceous glands and sweat glands after transplantation were more than that of the normal. The structure of the skin appendages was clear and intact. 2. Cyclosporine A and prednisone can prevent and control the rejection of the facial composite tissue allograft. 3. Beagle dogs could be used as an animal model for longer term observation of skin and appendages after facial allotransplantation.