EXPERIMENTAL ANIMAL MODELS IN FACIAL TRANSPLANTATION RESEARCH- A SYSTEMATIC REVIEW

Introduction: Face transplant is a vascularized composite allograft (VCA) used mainly in plastic and reconstructive surgery1. Since the first successful hand transplant2 in 1998, the development of different types of VCA and clinical applications have been challenged by the requirement for lifelong immunosuppression in order to avoid graft rejection. Advances in regenerative medicine and tissue engineering have made VCA a good option for patients suffering from tissue defects due to traumatic injuries, congenital deformities, or cancer3. The main goal of transplantation is to improve motor, sensory, and communicative functions. In recent years, experimental animal models have boosted the study of VCA. This review analyze the experimental work on face transplantation involving animal models.

Methodology: The search was conducted in the MEDLINE, LILACS, Cochrane and Scielo databases to select articles published from 2006 to 2022, written in english, portuguese and spanish. The articles must address face transplantation (partial or total) in animal models. A total of 37 publications were considered.

Results: There were analyzed 15 publications involving rodent models, 12 using swine animal models and 10 involving other animal experimental models.

Discussion: Animal models of vascularized composite allograft (VCA) have become relevant for establishing a robust scientific basis for advancing face transplantation in humans. Due to the possibility of using pure and genetically defined strains, the available molecular units, and the availability of monoclonal antibodies, rodents are useful tools for basic immunological studies4. On the other hand, because they resemble human models, large animal experiments allow anatomical dissections with better visualization. With this, it is possible to obtain relevant data and enough experience to start human experiments5.
The available data shows that animal models are valuable resources for studies in face transplantation. As more data becomes available, estimates of sensitivity, specificity, and accuracy can be refined. Current clinical challenges in face transplantation revolve around the risks of immunosuppression, achieving recipient-specific tolerance, and optimizing nerve regeneration. Knowledge accumulated with animal models can be combined with clinical experience to refine understanding of the functional and immunological challenges of this surgical technique.

Conclusion: The use of small animal models shows promise for immunological studies, while the use of large models shows importance for the development and improvement of surgical techniques in face transplantation.

References:
1. Alberti FB, Hoyle V. Face Transplants: An International History. Vol. 76, Journal of the History of Medicine and Allied Sciences. Oxford University Press; 2021. p. 319–45.
2. Petruzzo P, Badet L, Gazarian A, Lanzetta M, Parmentier H, Kanitakis J, et al. Bilateral hand transplantation: Six years after the first case. American Journal of Transplantation. 2006 Jul;6(7):1718–24.
3. Siemionow M. Vascularized composite allotransplantation: a new concept in musculoskeletal regeneration. J Mater Sci Mater Med. 2015 Dec 1;26(12).
4. Jeong Y, Jeon S, Eun S. Validation of Animal Models for Facial Transplantation Research. Transplant Proc. 2020 Jul 1;52(6):1884–90.
5. Brandacher G, Grahammer J, Sucher R, Lee WPA. Animal models for basic and translational research in reconstructive transplantation. Vol. 96, Birth Defects Research Part C - Embryo Today: Reviews. 2012. p. 39–50.

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