[Establishment of composite facial and scalp allograft transplantation model in canine].

Objective: To develop an experimental model of composite facial and scalp allograft in canine in order to investigate technical and immunological aspects and functional recovery of facial muscles of this new approach to facial reconstruction.

Methods: (1) Anatomic study: Four mongrel dogs were used for anatomical dissection of the head and neck region and for harvesting flap experiment. (2) Autologous transplantation (group I): Three types composite facial and scalp autologous transplantation were performed in five mongrel dogs. Type I composite tissue flap (group I a n = 2) included bilateral external ear and orbicularis oculi muscle. Type II (group I b n = 1) included single-lateral external ear, orbicularis oculi muscle, external nose upper and lower lip. Type III (group I c n = 2) included single - lateral external ear and orbicularis oculi muscle. (3) Allograft transplantation (group II): In group II a (n = 2), two allograft transplantation were performed with type III composite facial and scalp . In group II b (n = 4), four allograft transplantation were performed with the modified type III composite facial and scalp which included single - lateral external ear, orbicularis oculi muscle and one third of inferior tarsal plate and palpebral conjunctiva. To prevent allograft rejection, Cyclosporin A (CsA) and Methylprednisolone (MP) or Prednisone (PS ) were combined used as immunosuppressive protocol . Dose of CsA was adjusted depending on its blood drug level. Electromyogram (EMG) of orbicularis oculi muscle was carried out at 4 weeks, 6 weeks, 12 weeks and 6 months postoperation.

Results: (1) The facial anatomic characteristic of dog is similar to that of human being, external carotid artery and external jugular vein afford good blood supply to composite facial and scalp. (2) The dogs in group I c were long-term surviving with leakage of salivary juice. (3) In group II a (n = 2), one dog presented rejection reaction at 28th day postoperation, the reversal of rejection was achieved by increasing the dose of CsA and prednisone and with topical clobetasol for 2 weeks, the dog survived indefinitely( > 309 days). In group II b (n = 4), there were three dogs survived indefinitely ( > 159 days, > 129 days, > 108 days) without complication, EMG showed the function of orbicularis oculi muscle was gradually improving.

Conclusion: The modified type III composite facial and scalp allograft transplantation model is an ideal model for facial allograft transplantation study.