Hand Transplantation: Current Status and Immunologic Obstacles

Hand transplantation is the most common form of modern composite tissue allotransplantation, with 89 cases reported worldwide since 1998. The procedure is a treatment option for complex injuries that leave patients with structural, functional, and aesthetic deficits that cannot be addressed by other means. Successful application of this technology requires a multidisciplinary approach, incorporating not only skilled hand surgeons, transplant surgeons, and transplant immunologists, but also hand therapists, psychiatrists, medical specialists, anesthesiologists, and so on. Its long-term results depend on proper patient selection, a technically successful operation, postoperative rehabilitation, and an immunotherapy protocol that prevents rejection. Recent advances in transplant immunology are shifting the focus from immunosuppression to immunoregulation. Despite the enormous antigen load associated with composite tissue allografts, hand transplant has become a clinical reality, with immunosuppression comparable to that of solid-organ transplants. Our understanding of hand transplantation is still evolving, and ongoing research is needed to improve functional outcomes and to decrease the morbidity associated with long-term immunosuppression. This review discusses the current protocols for upper extremity donation, transplant receipt, surgical techniques, postoperative rehabilitation and immunosuppression, nerve regeneration, functional outcomes, ethical issues, and financial considerations.

Abdominal Wall Transplant Surgery

The evolution and success of intestinal and multi-visceral transplantation over the past 20 years have raised the issue of difficult or even impossible abdominal closure, a topic rarely encountered in other fields of transplantation. Different techniques have been proposed to address this topic. The choice depends on the transplant team's expertise and/or the availability of a plastic surgery service. Abdominal wall transplant is a type of composite tissue allograft that can be utilized to reconstitute the abdominal domains of patients who undergo intestinal transplant, and the results are encouraging. It is an effective option to achieve primary abdominal closure after intestinal transplant. In its full-thickness form, it may be useful for monitoring rejection or viability of visceral organs. Our aim is to review the role of abdominal wall transplant in achieving tension-free closure of the abdomen.

Therapeutic application of T regulatory cells in composite tissue allotransplantation

With growing number of cases in recent years, composite tissue allotransplantation (CTA) has been improving the quality of life of patient who seeks reconstruction and repair of damaged tissues. Composite tissue allografts are heterogeneous. They are composed of a variety of tissue types, including skin, muscle, vessel, bone, bone marrow, lymph nodes, nerve, and tendon. As a primary target of CTA, skin has high antigenicity with a rich repertoire of resident cells that play pivotal roles in immune surveillance. In this regard, understanding the molecular mechanisms involved in immune rejection in the skin would be essential to achieve successful CTA. Although scientific evidence has proved the necessity of immunosuppressive drugs to prevent rejection of allotransplanted tissues, there remains a lingering dilemma due to the lack of specificity of targeted immunosuppression and risks of side effects. A cumulative body of evidence has demonstrated T regulatory (Treg) cells have critical roles in induction of immune tolerance and immune homeostasis in preclinical and clinical studies. Presently, controlling immune susceptible characteristics of CTA with adoptive transfer of Treg cells is being considered promising and it has drawn great interests. This updated review will focus on a dominant form of Treg cells expressing CD4⁺CD25⁺ surface molecules and a forkhead box P3 transcription factor with immune tolerant and immune homeostasis activities. For future application of Treg cells as therapeutics in CTA, molecular and cellular characteristics of CTA and immune rejection, Treg cell development and phenotypes, Treg cell plasticity and stability, immune tolerant functions of Treg cells in CTA in preclinical studies, and protocols for therapeutic application of Treg cells in clinical settings are addressed in this review. Collectively, Treg cell therapy in CTA seems feasible with promising perspectives. However, the extreme high immunogenicity of CTA warrants caution.

Temporalis myofascial flap coverage for extrusion of internal device after cochlear implantation

Two pediatric patients with internal device exposure of cochlear implant (CI) were treated successfully using vascularized temporalis myofascial flaps. The visible scarring was minimal, and the CI function was excellent. Although we used temporalis myofascial flaps for late complications of an implanted ear, it can also be used in a primary case to provide flap reinforcement. In conclusion, the temporalis myofascial flap technique is an ultimate surgical option that offers advantages for CI patients with flap-related problems.

Facial transplantation surgery introduction

Severely disfiguring facial injuries can have a devastating impact on the patient's quality of life. During the past decade, vascularized facial allotransplantation has progressed from an experimental possibility to a clinical reality in the fields of disease, trauma, and congenital malformations. This technique may now be considered a viable option for repairing complex craniofacial defects for which the results of autologous reconstruction remain suboptimal. Vascularized facial allotransplantation permits optimal anatomical reconstruction and provides desired functional, esthetic, and psychosocial benefits that are far superior to those achieved with conventional methods. Along with dramatic improvements in their functional statuses, patients regain the ability to make facial expressions such as smiling and to perform various functions such as smelling, eating, drinking, and speaking. The ideas in the 1997 movie "Face/Off" have now been realized in the clinical field. The objective of this article is to introduce this new surgical field, provide a basis for examining the status of the field of face transplantation, and stimulate and enhance facial transplantation studies in Korea.

Stem cell and research in plastic surgery

Regenerative medicine using stem cells has progressed significantly over the last decade. Plastic surgeons historically have used tissues of human being to restore various defect sites and utilized a single cell lines for the tissue regeneration. The cell sources (autologous or allogeneic), cell types (embryonic stem cell or adult stem cell), and source of tissues (bone marrow, muscle, adipose, cartilage, or blood) are very important for stem cell-based tissue coverage. Embryonic stem cells are pluripotent precursors obtained from the inner cell mass of the blastocyst and reported to be used for preventing muscle atrophy after peripheral nerve injury. Multipotent adult stem cells are easily accessed for plastic surgeons during many routine procedures. This article briefly review the current state of overall stem cell research and clinical applications in the plastic surgical field.