A transplant is an organ, tissue, or a group of cells removed from one person (the donor) and transplanted into another person (the recipient) or moved from one site to another in the same person. A skin graft is a common example of a transplant from one part of a person’s body to another part. A transplant between two people can cause a rejection process where the immune system of the recipient or host attacks the foreign donor organ or tissue and destroys it.
Composite transplants involve multiple tissues, usually including skin and soft tissues and sometimes musculoskeletal structures. Many of these procedures are now possible because of advances in immunosuppressive therapy. However, the procedures are ethically controversial because they typically do not extend life, are very expensive and resource-intensive, and can potentially cause morbidity and mortality due to infections.
The first successful composite transplants were hand transplants. Since then, perhaps as many as 10 different structures have been replaced in about 150 patients, with varying functional success rates.
The first hand transplantation was done in 1998. Since then, double hand and upper-extremity transplantations have been done. Recovery of the hand function varies widely; some recipients regain enough function and sensitivity to do daily activities.
Bone transplantation is used for reconstruction of large bony defects (eg, after massive resection of bone cancer). No viable donor bone cells survive in the recipient, but dead matrix from allografts can stimulate recipient osteoblasts to recolonize the matrix and lay down new bone. This matrix acts as scaffolding for bridging and stabilizing defects until new bone is formed.
Cadaveric allografts are preserved by freezing to decrease immunogenicity of the bone (which is dead at the time of implantation) and by glycerolization to maintain chondrocyte viability.
No postimplantation immunosuppressive therapy is used. Although patients develop anti-HLA antibodies, early follow-up detects no evidence of cartilage degradation.
The first face transplantation was done in 2005. As of 2011, 17 such procedures have been done worldwide. To date, no graft failure has been reported, but the recipient of the first face transplant died in 2016. Ethical questions about face transplantation are even more prominent than those about extremity transplantation because the surgical procedure is extremely demanding and the immunosuppression required puts the recipient at considerable risk of opportunistic infections.