A New Face Subunit Transplant Model in Mice, Containing Skin, Mandible, and Oral Mucosa for Future Face Vascularized Composite Allotransplantation Studies

Abstract

Background: In immunologic research, mice have advantages over other animals, such as low costs, easy handling, suitable life cycle, and adequate laboratory resources. However, vascularized composite allotransplantation surgery using mice is not popular, partly because of technical difficulties and high mortality rates. The authors’ goal was to demonstrate a face transplantation model in mice that includes skin, mandible, and oral mucosa. Methods: The authors developed a new syngeneic face transplantation model composed of skin, mandible, teeth, and oral mucosa in C57BL/6 mice. The following assessment included measuring the length of the right incisor on the transplanted mandibles, computed tomographic scan in one mouse for mandibular structure evaluation, and histologic examination of different tissue samples in another mouse for viability evaluation. Results: The authors performed five consecutive transplantations. The donor vessels were the common carotid artery (approximately equal to 0.4 mm) and the anterior facial vein (approximately equal to 0.2 mm), and the recipients were the common carotid artery and the posterior facial vein (approximately equal to 0.4 mm). The mean operative time was 80 minutes for the donor and 123 minutes for the recipient. There were neither flap failures nor animal deaths. The follow-up was 6 months. The right incisor of the transplant grew at different rates in all cases. Histologic samples showed viability in all tissues, including mandibular bone marrow. Computed tomography demonstrated normal structure of the transplanted bone. Conclusion: The authors’ syngeneic partial face transplantation model in mice, which included skin, oral mucosa, and mandible with teeth, should be useful for future face allotransplantation research, as the myriad of tissues it provides, of different immunomodulatory functions, is similar to that in the clinical scenario.

Sustained Release of Tacrolimus Embedded in a Mixed Thermosensitive Hydrogel for Improving Functional Recovery of Injured Peripheral Nerves in Extremities

“…The loss of reinnervation results in the permanent loss of function of a limb; thus, promoting the improvement of the motor and sensory function of the transplanted limb through the recovery of peripheral nerves is paramount. Therefore, in VCA, nerve anastomosis needs to be performed in addition to vascular coaptation between the allografts and recipients, meaning that two challenges must be faced: allograft rejection [ 52 , 53 , 54 ] and nerve regeneration [ 3 ]. Encapsulated-tacrolimus hydrogel, with its two properties of inhibiting allograft rejection and promoting nerve regeneration, therefore holds promise for allogeneic limb transplantation.…”

Current global research on mandibular defect: A bibliometric analysis from 2001 to 2021

“…Wei Fu-chan of Chang Gung University in Taiwan mainly published clinical studies involving vascularized free flaps for mandibular defect repair ( Chang and Wei, 2021 ). This year, research has expanded to the mandibular allograft facial reconstruction field, which has a high academic influence ( Cardona et al, 2019 ; De Paz et al, 2021 ).…”

The Mandible Ameliorates Facial Allograft Rejection and Is Associated with the Development of Regulatory T Cells and Mixed Chimerism

“…We established the mouse hemiface transplant model, which comprises the skin, muscle, mandible, oral mucosa, and vessels and can be used for VCA studies [32]. The placement of the transplanted hemiface on the neck can reduce the risk of autonomy (mice biting an insensate flap) and increase surgery success.…”

“…We established microsurgical procedures for a heterotopic face transplantation model in mice [32] and describe them briefly as follows. For anesthesia, a mixture of ketamine and rocuronium was used in the donor mice and isoflurane in the recipient mice.…”

“…However, different kinds of facial tissues elicit different degrees of rejection. To investigate strategies for achieving facial allograft tolerance, we established a mouse facial transplant model including skin, muscle, the mandible, teeth, oral mucosa, and vessels for future facial VCA studies [32].…”