Xenograft Health Dictionary

A transplant from one animal to another of a di?erent species. It is also known as a xenograft.... heterograft

The process of transplanting healthy tissue from one part of the body to another (autografting), from one person to another (allografting), or from an animal to a person (xenografting).

Grafting is used to repair or replace diseased, damaged, or defective tissues or organs. The most common operations of this type are skin graft, bone graft, bone marrow transplant, corneal graft, kidney transplant, heart transplant, liver transplant, heart–lung transplant, heartvalve surgery, and microsurgery on blood vessels and nerves.

With autografting, the grafted tissue is usually assimilated well into the surrounding tissue at the new site.

The general risks of tissue rejection following other forms of grafting are discussed in transplant surgery.... grafting

1. n. any organ, tissue, or object used for *transplantation to replace a faulty part of the body. A *skin graft is used to heal a damaged area of skin. A *bone graft can be performed using natural bone or a synthetic material. A kidney removed from a live or dead person and transplanted to another individual is described as a kidney (or renal) graft. Corneal grafts are taken from a recently dead individual to repair corneal opacity (see keratoplasty). Diseased coronary arteries may be replaced by a *coronary artery bypass graft. Artificial grafts are used to replace diseased peripheral arteries and heart valves. 2. vb. to transplant an organ or tissue. See also allograft; xenograft.... graft

n. (in transplantation) the destruction by immune mechanisms of a tissue grafted from another individual. Antibodies, complement, clotting factors, and platelets are involved in the failure of the graft to survive. *Allograft rejection is a vigorous response that can be modified by drugs (such as ciclosporin and corticosteroids) and antibodies against T cells; *xenograft rejection is an acute response that is at present beyond therapeutic control.... rejection

n. the implantation of an organ or tissue (see graft) from one part of the body to another or from one person (the donor) to another (the recipient). Success for transplantation depends on the degree of compatibility between donor and graft: it is greatest for *autografts (self-grafts), less for *allografts (between individuals of the same species), and least for *xenografts (between different species; see xenotransplantation). Skin and bone grafting are examples of transplantation techniques in the same individual. A kidney transplant involves the grafting of a healthy kidney from a donor to replace the diseased kidney of the recipient: renal transplantation is the second commonest example of human transplant surgery using allografts (after corneal grafts – see keratoplasty). Bone-marrow, blood-stem-cell, heart, heart–lung, pancreatic, and liver transplants are also very successful. Patients have undergone laryngeal transplantation following *laryngectomy. Transplanting organs or tissues between individuals is a difficult procedure because the recipient’s immune system perceives the transplant as a foreign object and rejects it. Special treatment (e.g. with *immunosuppressant drugs) is needed to prevent transplant rejection, and the less common but equally devastating effects of an attack by the graft’s immune cells on the host.

Ethical questions arise over donated organs. If the donor is living, is the organ properly a *gift? If the donor has recently died, how has the death been judged and has *consent been given explicitly by the patient or surviving relatives (opting in) or is it assumed if the donor has not forbidden it (opting out)?... transplantation