Sensorimotor Recovery After Partial Facial (Mystacial Pad) Transplantation in Rats

Abstract

Most research in facial transplantation has been conducted in rats. This skill demanding model has a steep learning curve and is accompanied by high mortality rates. Investigations were carried out to minimize these disadvantages and a whiskers flap properly named mystacial pad flap, was developed. The mystacial pad contains the whiskers follicles of the rat, and our aim was to investigate the effect of repairing the nerves on the whiskers function after mystacial pad allotransplantation in rats. A total of 56 animals were studied in 6 groups. In the main study group (VI), 16 semi-allogenic vascularized mystacial flaps were transplanted from Lewis-Brown-Norway (RT1(l+n)) to Wistar-Lewis (RT1(l)) rats. This group was divided in 2 subgroups; in subgroup VIa (nonneurotized alloflap transplant group, n = 8), alloflaps were transplanted without nerve repairs, whereas in subgroup VIb (neurotized alloflap transplant group, n = 8) the facial and trigeminal nerves were repaired. Animals were kept under tapered doses of tacrolimus immunosuppression monotherapy. Clinical and neurophysiological explorations were performed to evaluate sensitivity and motor voluntary activity of the mystacial region after 6 weeks. Animals were euthanized after 8 weeks and histologic studies were performed. In group VI, each procedure required an average of 3.5 hours, and 87.5% of the recipients survived for 8 weeks. Sensitivity, motor activity, and histologic signs of recovery were found in the mystacial pad allotransplants after 6 weeks. Mystacial pad allotransplants in which nerves were repaired showed clinical, neurophysiological, and histologic signs of recovery. A functional facial subunit was successfully transplanted and sensorimotor function recovery could be demonstrated in rats.

Supraorbitary to infraorbitary nerve transfer for restoration of midface sensation in face transplantation: Cadaver feasibility study

“…11,12 In addition, facial transplantation in animal models has shown significantly better sensory outcomes in transplants where nerve coaptations have been performed. [13][14][15] Based on the above, sensory nerve coaptation should be performed to maximize the functional outcomes in face transplantation. In addition, the use of FK506 (Tacrolimus) in face transplant coupled with nerve repair might also provide better outcomes in sensory recovery of the graft since it has been shown in the laboratory to enhance nerve regeneration and to accelerate functional recovery after nerve injury.…”

A new total hemiface allotransplantation model in rats

“…This novel model is comprised of all tissue types of the facial region, such as the oral and nasal mucosa, different types of cartilage, the upper and lower eyelid structures, the upper and lower lip structures, striated muscle and bone. The presented model is different from the previously described hemiface and single unit of face transplantation models since it includes midface structures, the nose, premaxilla, and eyelids . This model was specially designed for reconstruction of a composite midface defect.…”

Face transplantation in rats. Reproducibility of the experimental model in Brazil

“…The development of an experimental model requires a certain learning curve and is followed by high animal mortality due to the complexity of this procedure. The use of experimental models of allotransplants has enabled the development of surgical techniques and immunosuppressive protocols, contributing to the future adoption of this method as an alternative therapy for complex facial defects [26][27][28][29][30] .…”