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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. [ABSTRACT FROM AUTHOR]

Summary: Background: The limb-threatening large soft tissue defects that occur on the feet of type 2 diabetic patients have complex causes and are less likely to be corrected by free flap reconstruction compared to those in non-diabetic patients. We retrospectively analysed factors affecting the success of free flap transfer for necrotising soft tissue defects of the lower extremities in patients with type 2 diabetes. Methods: This study included 33 diabetic patients whose feet were treated with free flap transfers. All patients had limb-threatening large soft tissue defects with tendon or bone exposure. The operative results were divided into three groups at 1 month post-operatively: the complete healing group, and the complication group, with either partial necrosis requiring additional simple procedures or flap failure with total necrosis. Nine preoperative factors were analysed: (1) ankle brachial index, (2) HbA1c, (3) BMI, (4) the smoking factor, (5) atherosclerotic calcifications (6) serum creatinine levels (>1.28 mg dL−1 vs. <1.28 mg dL−1), (7) GFR, (8) wound infection and (9) wound defect size. Results: Of the 33 patients, 15 showed complete healing and 18 showed complications of the free flap (eight partial necrosis and 10 flap failure). No atherosclerotic calcifications were found in the patients in the complete healing group, although they were found in 12 patients in the complication group, and this difference was significant (p = 0.002). Patients with serum creatinine levels >1.28 mg dL−1 had significantly higher free flap transfer complication rates than those with serum creatinine levels <1.28 mg dL−1 (p = 0.038). Conclusions: This study analysed the risk factors of free flap reconstruction for limb-threatening large soft tissue defects on the feet of type 2 diabetic patients. Serum creatinine levels >1.28 mg dL−1 and atherosclerotic calcifications were confirmed as risk factors for flap survival. [Copyright &y& Elsevier]

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.

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.