A Model for Functional Recovery and Cortical Reintegration after Hemifacial Composite Tissue Allotransplantation

Abstract

The ability to achieve optimal functional recovery is important in both face and hand transplantation. The purpose of this study was to develop a functional rat hemifacial transplant model optimal for studying both functional outcome and cortical reintegration in composite tissue allotransplantation. Five syngeneic transplants with motor and sensory nerve appositions (group 1) and five syngeneic transplants without nerve appositions (group 2) were performed. Five allogeneic transplants were performed with motor and sensory nerve appositions (group 3). Lewis (RT1) rats were used for syngeneic transplants and Brown-Norway (RT1) donors and Lewis (RT1) recipients were used for allogeneic transplants. Allografts received cyclosporine A monotherapy. Functional recovery was assessed by recordings of nerve conduction velocity and cortical neural activity evoked by facial nerve and sensory (tactile) stimuli, respectively. All animals in groups 1 and 3 showed evidence of motor function return on nerve conduction testing, whereas animals in group 2, which did not have nerve appositions, did not show electrical activity on electromyographic analysis (p < 0.001). All animals in groups 1 and 3 showed evidence of reafferentation on recording from the somatosensory cortex after whisker stimulation. Animals in group 2 did not show a cortical response on stimulation of the whiskers (p < 0.001). The authors have established a hemiface transplant model in the rat that has several modalities for the comprehensive study of motor and sensory recovery and cortical reintegration after composite tissue allotransplantation.