transplantation(redirected from xenogeneic transplantation)
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Occasionally an emergency requires an organ to be transplanted from one place to another within the body. Kidneys, for example, have been relocated to enable them to continue functioning after the ureters have been damaged. Transplantation of an organ within the body, known as autotransplantation or an autologous graft, requires delicate surgery but otherwise poses no particular problem.
Eye surgeons have developed the procedure called corneal transplantation or keratoplasty, in which part or all of a diseased cornea that has become opaque is removed and replaced by healthy corneal tissue from an eye bank. Cartilage and bone are other tissues that are not difficult to transplant from one individual to another. Cartilage is particularly able to be made into various shapes and so is widely used in reconstructive surgery. Bone grafts are sometimes used instead of metal plates in operations to repair fractures, and they can also be used to replace diseased bone. Grafts made of synthetic materials may also be used, such as Dacron vascular grafts that replace parts of blood vessels.
Kidney transplants have been performed on dogs since 1902, but remained in the experimental realm in humans until a ground-breaking operation was performed in 1954 in Boston. A kidney from one identical twin was successfully implanted in the other to replace his diseased kidneys. Since that time kidney transplantations have been the most successful of transplantations, primarily because there are artificial kidney machines available (see dialysis and hemodialysis), and also because the kidney is a paired organ. This means that the donor need not be cadaveric but can be a living person (such as a relative of the recipient) and can be selected on the basis of tissue-type compatibility to avoid fatal rejection of the organ by the recipient.
In 1967 the South African surgeon Christiaan N. Barnard transplanted a human heart. Transplants of hearts and other vital organs are now being done at an increasing rate throughout the world. There are ethical and legal implications of obtaining healthy organs for transplantation, which still have not been completely resolved.
In order to minimize rejection and improve the chances of survival of a transplanted organ, efforts are made to match as closely as possible the blood types and tissue types of the donor and recipient. First, the blood is tested for ABO or blood type compatibility. Then, tissue typing is done to identify the protein antigens that are specific to each individual. These antigens are the hla antigens (HLA), so called because they are easily identifiable on leukocytes. The more compatible these antigens are between donor and recipient, the less likely tissue rejection will occur. A third test that is done is crossmatching, which involves mixing the intended recipient's serum with lymphocytes from the potential donor. A positive reaction would show destruction of the donor's cells by antibodies in the recipient's serum, thus eliminating the possibility of using an organ from that particular donor. The probability of survival of a transplanted organ is highest when the donor is a sibling who is HLA identical to the recipient.
Control of the immune response in the recipient is attempted by the use of immunosuppressive agents such as antilymphocyte globulin and antimetabolites, which tend to suppress the growth of rapidly dividing cells, and cyclosporine, which inhibits T-cell function. corticosteroids also are used because of their antiinflammatory effect. All of the chemicals used in transplantation therapy interfere in some way with the body's normal defense mechanisms. For this reason a delicate balance must be maintained in their administration so as to avoid tipping the scales either in the direction of rejection of the organ on one side or a fatal infection on the other.
See also: graft.
transplantationThe moving of a tissue or organ from one person–the donor or, less commonly, from a different site on the same person, to another person–the recipient, to replace a malfunctioning organ or organ system; solid organ and hematopoietic precursor transplantations are performed with increasing immunologic impunity in BM, bone matrix, heart valves, heart, heart-lung, kidney, liver, pancreas, skin and intestine, largely due to the availability of agents–eg, cyclosporine and tacrolimus–FK 506, which minimize the otherwise limiting complications of GVHD Complications Transplanted tumors Statistics Kidney 14,800; liver 5,350; heart 2155; lung 1042; kidney/pancreas 905; pancreas; 349; intestine 83; heart/lung 22; in Nov, 2003, 83,200 were on waiting lists at the 255 US medical centers that perform transplantations. See Allogeneic transplantation, Allogeneic bone marrow transplantation, Autologous bone marrow transplantation, Autologous chondrocyte transplantation, Bone marrow transplantation, Death row transplantation, Fetal tissue transplantation, Graft-versus-host disease, Hair transplantation, Half-side transplantation, Hand transplantation, Heart transplantation, Heart-lung transplantation, Hematopoietic stem cell transplantation, Hepatocyte transplantation, Islet cell transplantation, Laser hair transplantation, Laser-assisted transplantation, Liver transplantation, Lung transplantation, Multiorgan transplantation, Organ transplantation, Organ cluster transplantation, Orthotopic transplantation, Pancreatic islet transplantation, Pancreatic transplantation, Procurement, Renal transplantation, Skin graft, Small intestine transplantation, Stem cell transplantation, Syngeneic transplantation, Transpecies transplantation, UNOS.
See also: graft
transplantationthe transference of an organ or tissue from a donor to a recipient in need of a healthy organ or tissue. In recent years kidney, lung, heart and liver transplants have taken place. For successful transplantation to occur similar tissues types must be involved (see HLA SYSTEM and genetical similarity is one of the best ways of ensuring this. Drugs which inhibit the normal IMMUNE RESPONSES are used, but these also inhibit the body's defence against microorganisms. Rejection of foreign tissue is part of the normal response of the body and the development of drugs that will prevent rejection but which will not affect the normal response to microorganisms is actively being researched.
Patient discussion about transplantation
Q. What is a bone marrow transplant? I wanted to enter myself as a potential bone marrow donor and wanted to know first of all what bone marrow is? What does a bone marrow transplant mean and how is it done?
Q. Has anyone had experience with a corneal transplant because of keratoconus?
good luck :)
Q. I would like to know what it takes to get on a liver transplant list.. I have been diagnosed with cirrhosis of the liver. I have been clean and sober now over 2 years... I have also been hospitalized more times than i don't like talking about but I have been admitted for high amounts of ammonia levels, low blood pressure, and dehydration