transplantation
(trans‵plan'tā'shŏn 
)
- The grafting of living tissue from its normal position to another site or the transferring of an organ or tissue from one person to another. Organs and tissues successfully transplanted include the heart, lung, kidney, liver, pancreas, cornea, large blood vessels, tendon, cartilage, skin, bone, and bone marrow. Brain tissue has been implanted experimentally to treat Parkinson disease. The matching of histocompatibility antigens that differentiate one person's cells from another's helps prevent rejection of donated tissues. Cyclosporine, tacrolimus, corticosteroids, monoclonal antibodies, and other immunosuppressive agents have been approx. 80% effective in preventing rejection of transplanted organs for 2 or more years.
SEE: autotransplantation; graft; heart transplantation; organ donation; renal transplantation; replantation.
Patients who have received organ transplants and who are maintained on immunosuppressant drugs should generally avoid vaccination with live, attenuated organisms unless these vaccinations are specifically approved by their health care providers. Inactive vaccines are usually preferable for these patients. - In dentistry, the transfer of a tooth from one alveolus to another.
allogeneic t.Transplantation of material from a donor to another person.
autologous chondrocyte t.Autologous chondrocyte implantation.
autologous t.Transplantation of tissue or cells from one location in the body to another site.
ABBR: ABMT
The harvesting and preservation of a patient's own blood-forming cells, followed by their eventual reintroduction into a patient. The procedure may be used to treat a variety of cancers and autoimmune disorders. Current practice is to mobilize stem cells into the blood stream with growth factors and then to collect and filter the blood by leukapheresis. In leukapheresis stem cells are identified by a cell surface antigen called CD34. After desirable blood-forming cells with this antigen are removed from the patient's blood, high-dose chemotherapy, monoclonal antibody therapy, or radiation may be used to purge the marrow of diseased cells. Healthy CD34+ cells capable of rebuilding the bone marrow are then returned to the patient and stimulated to reproduce. SYN: autologous hematopoietic stem cell transplantation.autologous hematopoietic stem cell t.Autologous bone marrow transplantation.
autoplastic t.Transplantation of tissue from one part to another part of the same body.
ABBR: BMT
Transplantation of blood-forming stem cells from the bone marrow from one person to another (allogeneic transplantation), or from a person to him or herself (autologous transplantation). It is used in treating aplastic anemia, thalassemia and sickle cell anemia, immunodeficiency disorders, acute leukemia, chronic myelogenous leukemia, non-Hodgkin lymphoma, Hodgkin disease, and testicular cancer, and after radiation therapy, as indicated.chain t.The pairing of living organ donors who want to give an organ to someone with whom they are antigenically mismatched with other pairs of donors and recipients who share appropriate antigens, antibodies, and blood types.
domino t.A procedure in organ transplantation in which an organ recipient receives one organ from a donor and donates his or her replaced organ to another person.
double t.Tand em transplantation.
fat t.In cosmetic surgery, the movement of adipose tissue from one body site to another to augment structure, change body contours, or reduce skin wrinkling.
hair t.A surgical procedure for placing plugs of skin containing hair follicles from one body site to another. This time-consuming technique is used to treat baldness.
heart t.Surgical transplantation of the heart from a patient who died of trauma or a disease that left the heart intact and capable of functioning in the recipient. The only absolute contraindications are uncontrollable cancer or infection, irreversible pulmonary vascular disease, or a separate life-threatening disease; in general, however, patients over 65, those with severe renal or liver disease, and those with a history of noncompliance with medical regimens do not receive heart transplants. The major barrier to heart transplantation is the lack of donors; the number of potential recipients is approx. 10 times the number of donors each year.
After receiving a heart transplant, continuous immunosuppression with cyclosporine, corticosteroids, or related drugs is required to prevent rejection of the donated organ. Acute episodes of rejection are treated with monoclonal antibodies (OKT3) or antilymphocyte immune globulin. Clinical signs of rejection (fatigue, dyspnea, hypotension, and extra heart sounds) are nonspecific; therefore biopsies are performed frequently during the first 2 years after surgery. Average patient survival is greater than 75% 1 year after the surgery, and greater than 50% after 10 years.
SEE: rejection (2).
Variant: hematopoietic stem cell transplantation
ABBR: HCT, HSCT
Removal of blood-forming cells from one person and their infusion into another. It is used primarily but not exclusively to treat leukemias and lymphomas.heteroplastic t.Transplantation of a part from one individual to another individual of an unrelated species.
heterotopic t.Transplantation in which the transplant is placed in a different location in the host than it had been in the donor.
homotopic t.Transplantation in which the transplant occupies the same location in the host as it had in the donor.
kidney t.Renal transplantation.
liver t.Surgical implantation of a donor liver into a patient with end-stage liver disease. The disease may be caused by alcoholic cirrhosis, chronic cholestatic diseases, chronic or fulminant hepatitis, or toxic liver destruction. Immunosuppressive drugs (such as cyclosporine) must be taken after the procedure to prevent rejection of the grafted organ. With optimal care, about 75% of grafted livers remain functional after 1 yr. Patients with HIV or uncontrolled systemic infections, metastatic cancer, active alcoholism, or other severe cardiac, pulmonary, or neurological illnesses are not cand idates for the procedure. In the U.S. about 4000 liver transplants are performed annually.
lung t.Grafting of a donor lung into a recipient with end-stage lung disease, usually caused by pulmonary fibrosis, chronic obstructive lung disease, or pulmonary hypertension. Lung transplantation may be performed as a single-organ operation or as part of a combined heart-lung transplantation, e.g., in congenital heart disease. Immunosuppressive therapy with cyclosporine or tacrolimus, azathioprine, and corticosteroids is necessary to minimize the risk of rejection, which is caused by T lymphocyte activity against the donor tissue. Rejection is diagnosed through the use of bronchial biopsies and pulmonary function tests. Acute rejection, characterized by dyspnea, fever, hypoxemia, rales, and tachypnea, must be differentiated from infection. Chronic rejection, a problem in 25% to 50% of cases, presents as bronchiolitis obliterans and occurs 6 to 14 months after the transplant. Flow rates progressively decrease, with few additional symptoms; bronchodilator therapy is not effective, and giving higher doses of immunosuppressives has mixed success. Sixty percent of lung transplant recipients live 2 years.
t. of the pancreas The implantation of a part of the pancreas (such as cells of the islets of Langerhans) or the entire gland from a donor into a patient whose own pancreas is no longer functioning. In the diabetic patient, pancreas transplantation provides an endogenous source of insulin and may be combined with kidney transplantation. The risks of the surgery and the immunosuppression associated with transplantation must be weighed against the kidney, nerve, and retinal damage associated with uncontrolled diabetes mellitus. Some potential complications of the procedure include infections, blood clotting in the vessels that supply the graft, hypoglycemia, bladder injury, and organ rejection. To prevent rejection, immunosuppressive drugs, such as tacrolimus, mycophenolate mofetil, cyclosporine, and corticosteroids, may be used. Episodes of rejection are treated with the monoclonal antibody OKT3. The 1-year survival rate of combined pancreas-kidney transplants is about 80%, when performed at institutions where the procedure is done frequently.
SEE: diabetes mellitus; rejection.
renal t.Grafting of a kidney from a living donor or from a cadaver to someone with renal failure. It is used as the definitive form of renal replacement for patients with kidney failure. Tissue typing for human leukocyte antigens (HLAs) as well as ABO blood groups is used to decrease the likelihood of acute or chronic rejection. Family members are often the best-matched donors. In patients with diabetes mellitus, combined renal and pancreatic transplants are sometimes performed with a very high likelihood of success. The high success rate of kidney transplants (85% to 95% at 2 years) is primarily due to immunosuppressive drugs such as corticosteroids, cyclosporine, mycophenolate, and tacrolimus. Because cyclosporine is nephrotoxic, careful monitoring of serum drug levels after transplantation is required. SYN: kidney transplantation.
SEE: major histocompatibility complex; suppressive immunotherapy.
small intestine t.A semi-experimental procedure in which the small intestine is replaced with a donor organ.
ABBR: SOT
Transplantation of a kidney, liver, or the pancreas rather than of bone marrow, for example.split-cornea t.The separation of the anterior lamella of a donor cornea from the endothelium/Descemet membrane so that each part can be used separately in different recipients. The anterior corneal epithelium can be used to treat keratoconus, and the deeper tissue could be used to treat Fuch endothelial dystrophy.
ABBR: SLT
Surgical division of a donor liver into two parts, each of which is implanted into a different recipient.syngeneic t.A specific type of allogeneic transplantation of material between identical twins.
tand em t.The use of sequential bone marrow transplants to treat cancer. An initial autologous transplant is followed by a second, e.g., if remission is not achieved after the first transplant. SYN: double transplantation.