Is histocompatibility testing needed for composite tissue transplantation?

Abdominal wall allotransplantation

Allotransplantation of vascularized composite tissue is a new field of transplantation surgery. One application of this technique is abdominal wall transplantation used as a supplementary procedure to the transplantation of visceral organs in patients with abdominal compartment deficits. As abdominal wall closure problems are experienced in around 30-40% of such patients, peer reviewed conclusions on the viability of various options, are important for an informed choice of possible procedures. This review focuses on the abdominal wall allotransplantion procedure. Our search provided 35 appropriate references which we used to support our findings as follows: abdominal wall transplantation was performed in 33 patients at seven centres. Of these, 30 had a full thickness abdominal wall transplanted from the same donor, 3 from a second donor. Three had visceral organ transplants and in addition, the posterior sheet of the rectus muscle fascia. In summary, our findings were that abdominal wall allotransplantation does not jeopardize the outcome of visceral organs transplantation. There is no higher risk of complications or rejection of the visceral organs. There have been no fatalities as a direct result of complications due to abdominal wall transplantation. Finally, the transplanted abdominal wall may provide an early warning of rejection before diagnostic tests on the bowel are symptomatic.

Vascularized composite allograft-specific characteristics of immune responses

Vascularized composite allograft (VCA) transplantation, or reconstructive transplantation, has revolutionized the treatment of complex tissue and functional defects. Despite arriving during an age in which the immunology of solid organ transplant rejection has been investigated in much detail, these transplants have offered new perspectives from which to explore the immunobiology of transplantation. VCAs have a number of unique molecular, cellular, and architectural features which alter the character and intensity of the rejection response. While much is yet to be clarified, an understanding of these distinct mechanisms affords new possibilities for the control of immune responses in an effort to improve outcomes after VCA transplantation.

Vascularised composite allotransplants: Transplant of upper extremities and face

Transplantation of solid organs and bone marrow has become a highly acceptable and often the only available clinical solution in many situations. It has been practiced across the globe for quite a long time since the first kidney transplant in 1954. Transplantation of tissues other than these, which was termed composite tissue allotransplantation and currently as vascularised composite allotransplantation (VCA) is gaining acceptance as a solution for complex reconstructive problems. This involves the transfer of multiple types of tissue such as bone, muscle, nerve, skin and blood vessels. The advantage of these over the conventional reconstructive methods is its ability to give aesthetically and functionally superior equal composite substitute to the missing or deformed part. The composite tissues transplanted commonly include the upper extremities, face and abdominal wall. Among these, hand transplants were the first to be done and have been carried out more than any other VCA. This article reviews the current scenario of VCA especially of the hand and face, in the light of experience of the two bilateral hand transplants done recently in India.

Past, present, and future prospects for inducing donor-specific transplantation tolerance for composite tissue allotransplantation

Composite tissue allotransplantation (CTA) is among the most immunologically complex and newest transplant fields. Although the field has made considerable advances, there are still concerns that these procedures are performed to enhance quality-of-life issues and are not lifesaving procedures that restore physiologic function. Two challenges limit the widespread application of CTA; the first is chronic rejection, the most prevailing cause of organ allograft failure after transplantation; the second barrier is the numerous health complications associated with lifelong immunosuppressive therapy. Several tolerance-inducing strategies, including costimulatory blockade, T-cell depletion, mixed chimerism, and gene targeting of transplanted organs, have the potential to induce lifelong tolerance to organ allografts without chronic immunosuppression. Effective clinical tolerance protocols that improve CTA acceptance and offer an alternative to the requirement for chronic immunosuppressive therapy could be a major advance in the field. Tolerance would allow allotransplantation to provide a currently unmet need for reconstruction of large tissue defects. This article reviews the history of CTA, current challenges and complications, and offers future directions for CTA research in strategies to induce tolerance.

Hand transplantation. A future clinical option?

Transplantation of a vascularized limb or its components is defined as composite tissue allotransplantation, and is one of the newest areas in surgery. To date, 24 hands have been transplanted onto 18 recipients. The initial results have been promising, and hand transplantation may become an important procedure for functional restoration of upper limbs. However, the ethical aspects of using chronic immunosuppression for a condition which is not life threatening have been the subject of debate. In this article, we review the field of composite tissue allotransplantation.

Effects of major histocompatibility complex matching on graft survival in allogeneic rat limb transplantation

Differences in the major histocompatibility complex (MHC) between recipients and donors present a problem because of immunologic responses in graft rejection. The purpose of this study is to clarify the efficacy of MHC matching against acute graft rejection of allogeneic limb transplants in rats. Right hindlimb transplantations were performed using various MHC-mismatched pairs of inbred rats. The rats were classified into 5 groups according to the differences in subregions of the RT1 (rat MHC) between the recipient and the donor: group 1, RT1-A,B,D barrier (the differences of RT1-A,B,D subregions); group 2, RT1-A barrier; group 3, RT1-B,D barrier; group 4, RT1-B barrier; and group 5, RT1-D barrier. The mean survival time significantly decreased in group 1 and increased in group 4. The results suggest that MHC matching clearly improves survival of transplanted limbs. Specifically, both RT1-A and D matching is the most effective compatibility in prolonging survival time of allogeneic limb transplants in rats.