HEMIFACE TRANSPLANTATION IN THE MOUSE

Robert Sucher^1,2, Cheng-Hong Lin¹, Barbara Kern^2,1, Bettina Zelger³, Johann Pratschke², Stefan Schneeberger^2,1, W.P. Andrew Lee¹, Gerald Brandacher^2,1.

¹Department of Plastic and Reconstructive Surgery, Johns Hopkins University School of Medicine, Baltimore, MD, USA; ²Department of Visceral, Transplant and Thoracic Surgery, D. Swarovski Research Laboratory, Innsbruck Medical University, Innsbruck, Austria; ³Department of Pathology, Innsbruck Medical University, Innsbruck, Austria.

Background: To date rat models of experimental face transplantation have been widely used to study basic immunogenetics in composite tissue allotransplantation (CTA). Since the mouse, however, would be a superior model for CTA research we developed a novel surgical technique for allograft revascularization allowing us to perform hemiface transplantation in mice.

Methods: BALB/c hemifacial flaps were transplanted to BALB/c (group 1) or C57BL6 (group 2) recipients using a non-suture cuff technique for vascular anastomosis (n=6). Donor operation consisted of harvesting a myocutaneus hemiface flap with intact common carotid artery (CCA) and external jugular vein (EJV) using superfine microsurgical instruments. In the recipient, the graft was transplanted in an orthotopic position using the CCA and EJV for revascularization.

Results: After an initial learning curve, transplants could be performed with a constant and high success rate (78%). Operation time was comparable in all groups and lasted 120 ± 15 minutes for the donor and 150 ± 12 minutes for the recipient. All syngeneic grafts survived long term (>100 days). Allograft rejection in group 2 occurred within 14±2 days. H&E stains of syngeneic grafts revealed unaltered muscle and skin histology. Allogeneic grafts gradually showed distinct BANFF rejection patterns over time of rejection similar to those observed after human face transplantation.

Conclusion: This is the first model illustrating that mouse hemiface allotransplantation is technically achievable. The microsurgically demanding procedure may be used to investigate basic immunology and rejection as well as address questions related to nerve regeneration in reconstructive face transplantation.