Face transplantation—fantasy or the future?

Overcoming the immunogenicity of facial tissues is only one of the challenges; the other is whether it is technically feasible to transplant a face. To be transplantable, an organ must have a dominant blood supply that can be connected to the recipient's vessels. However, for a face allograft, blood supply alone is not sufficient to ensure function. Reinnervation is as important as vascular supply. Without motor and sensory nerve regeneration a face transplant would be functionally useless. Although the face is structurally complex, it has certain anatomical features that mean that both the vascular and neuronal supply can be technically achieved in a transplant. The face is supplied bilaterally by branches of one major artery, the external carotid, and drained bilaterally by one major vein, the external jugular. This means that the whole face could theoretically be maintained and transplanted on these vessels. Facial innervation is more complex. The muscles of facial expression are supplied by the facial nerve and sensation to the face is mainly provided by three branches of the trigeminal nerve. Joining of these to their recipient nerves is technically feasible. However, reinnervation not only relies on accurate apposition of nerves but also requires the regrowth of the recipient's neurons into the transplanted nerve. This has been the major limit in the success of nerve repair. There are emerging ways of accelerating the regeneration of nerves. The use of various growth factors and even certain immunosupressants leads to faster reinnervation.5,6 If rapid reinnervation can be achieved then transplantation of a full face or functional facial segment would be possible.