Porcine ear: A new model in large animals for the study of facial subunit allotransplantation

In the context of experimental development of vascularized composite tissue allotransplantation (VCA), the auricular model has been described in rats and humans, but not in pigs. A porcine ear transplant, however, represents an interesting experimental composite facial subunit allotransplant because of its reduced morbidity and its translational nature but mostly because it is composed of very different tissues. In this perspective, we studied the anatomical and surgical aspects of an ear subunit VCA in pigs. Our study was performed on 18 pigs: auricular and cervical regions were dissected without preparation (n = 12) or after latex injections (n = 2) in the common carotid artery (CCA). The angiosomes of the caudal auricular artery and superficial temporal artery were studied with selective injections (n = 2). The surgical harvesting protocol was established using the caudal auricular artery as arterial pedicle, and tissue perfusion was studied with injection of Indian ink (n = 1) and angio-CT (n = 1). Finally, two in vivo orthotopic allotransplantations in four pigs were performed, followed by a short observation period. The caudal auricular artery was shown to be the dominant artery to the auricle ensure complete ear perfusion. Venous drainage relied on the caudal and rostral auricular veins, dissected down to the maxillary and external jugular veins. In vivo allotransplantations confirmed proper auricular vascularization on the sole caudal auricular artery under physiological conditions. We have described a new subunit model for experimental face VCA in large animals. Our study reports a reliable harvesting method and easily performed transplantation with a single-based arterial pedicle.