Types of Transplants

Kidneys

Kidneys are the most common organs to be transplanted. Kidneys remove waste products from the blood stream. If they fail, often as a result of diabetes mellitus or cancer, a person can die from the buildup of these toxic materials.

The waste products can be removed artificially through a process called kidney dialysis, but the patient must be hooked up to the dialysis machine two to three times each week for as long as 12 hours at a time.

Kidney transplants free the recipient from dependence on dialysis. If the kidney is rejected, the patient must go back on dialysis or receive another transplant.

The first successful transplant of any organ was performed in 1954, when American surgeon Joseph Murray successfully transplanted a kidney donated from the recipient’s twin brother.

In the United States, some 13,290 kidney transplants were performed in 2000, of which 5,227 came from living donors. The one-year survival rate for kidney transplant patients is about 95 percent. Some kidney transplant patients have survived more than 25 years.

Because people have two kidneys but need only one, a living relative often serves as a donor, retaining one kidney for his or her own use. About one-third of transplanted kidneys come from living relatives and about two-thirds are from someone who recently died.

Many patients whose kidney failure was caused by diabetes mellitus receive a pancreas transplant at the same time. The pancreas normally secretes insulin, a substance that helps the body use and store sugars. In some diabetics, the body’s immune system destroys insulin-secreting cells in the pancreas.

In many cases, the disease can be controlled with shots of insulin. However, if the diabetic requires a kidney transplant, the surgeon will often transplant a pancreas at the same time. In 2000, there were 436 pancreas transplants and 914 simultaneous kidney and pancreas transplants performed in the United States. The one-year survival rate for pancreas transplant patients is about 95 percent.

Heart Transplant

Heart transplants are perhaps the most dramatic of all organ transplants because without a functioning heart, a patient cannot survive more than a few minutes. The heart is also more sensitive to a lack of blood than other organs, and can be preserved for only a few hours without damage.

The first successful heart transplant was conducted in December 1967 by South African surgeon Christiaan Barnard. It was not until cyclosporine was approved for clinical use in the United States in 1983 that heart transplants gained widespread use. Most patients are able to resume a normal life about six months after surgery, and about 84 percent of them survive the first year. In 2000, about 2,200 patients received heart transplants, and 48 received heart-lung transplants, in the United States.

Liver failure caused by cirrhosis, cancer, or hepatitis can be fatal. The liver is the only internal organ with the capacity to regenerate. This capacity provides the surgeon additional flexibility in treating liver damage. For instance, if the damage is not very severe, a temporary transplant can take over the liver’s function while the patient’s own liver recovers. It is also possible to remove part of a liver from a living donor and transplant it. After the surgery both the donor’s liver and the transplanted portion will grow to full size. In 2000, about 4,900 livers were transplanted. The one-year survival rate is about 84 percent.

Lungs Transplant

Lung transplants are used to replace a single diseased lung, and sometimes both lungs. In some cases lung disease has damaged the heart, and these cases may benefit from a combined heart-lung transplantation. Successful lung transplants are hampered by the difficulty in preserving a lung from a person who has recently died so that it is still viable by the time a proper recipient is found. In 2000, 956 lungs were transplanted in the United States. The one-year survival rate for lung transplants is about 74 percent.

Other organ transplant surgeries are being developed and some are still in the experimental stage. In 2000, 79 small intestines were transplanted in the United States to replace organs damaged by disease. Reliable survival data for intestine transplant patients are not yet available because the procedure is still experimental.

Tissue Transplant

The most common tissue transplant is blood transfusion, commonly used to replace blood lost by a person in an accident or during surgery. Other tissues commonly transplanted include bone marrow, corneas, skin, bone, cartilage, tendons, and blood vessels.

Bone marrow is the living tissue found in the center of many large bones of the body. Special cells in the bone marrow, called stem cells, are the source of both red blood cells, the primary component of blood, and white blood cells, the workhorses of the immune system. Certain blood diseases, including leukemia and sickle-cell anemia, are the result of the stem cells in the bone marrow producing faulty blood cells.

In some cases, these diseases can be treated by destroying all of the patient’s bone marrow and replacing it with new donor bone marrow that does not produce the faulty blood cells. Bone marrow transplants are also used in fighting breast and other cancers because intensive radiation or chemotherapy used to cure the cancer also kills the patient’s bone marrow, which must then be replaced with a transplant.

Bone marrow transplants require a closer matching of donor and recipient than is the case with other types of transplants. If the match is not good enough, the recipient’s body may reject the bone marrow or the white blood cells generated by the donor marrow can attack the recipient’s body, a phenomenon known as graft-versus-host disease.

About 30 percent of patients who require a bone marrow transplant have a close family member who is suitably matched. The rest must find a suitable donor. In the United States, the federal government has established the National Marrow Donor Program registry, which currently lists more than 4 million potential donors.

More than 1,500 bone marrow transplants occur every year in the United States from marrow donated from unrelated people. The success rate of a transplant depends on the disease being treated. Transplants to treat sickle-cell anemia have a 90 percent success rate, but success rates are only in the 30 to 60 percent range for other diseases.

Cornea Transplant

The cornea is the transparent front covering of the eye and is necessary for vision. Cornea transplants replace corneas that have become cloudy, swollen, or painful, usually as a long-term complication from cataract surgery.

Corneas can also become scarred after an injury or require replacement because of birth defects. Cornea transplants are very successful, with a success rate of more than 90 percent if the cornea is placed on the eye in such a manner that blood vessels do not come into contact with it. Without blood vessels, the body cannot send immune cells to attack the cornea.

About 33,000 cornea transplants are performed every year. Eye surgeons can also transplant scleral tissue, the fibrous tissue that forms the white of the eye. Sclera transplants are used to treat glaucoma patients and those requiring reconstructive eye surgery.

Skin was the first tissue transplanted, and researchers used skin transplants in the late 1950s and early 1960s to decipher the immune system response to transplants. Most skin transplants are so-called autografts, in which skin is taken from one site on the recipient’s body and grafted onto an injured site, thus avoiding the problems with rejection.

However, in cases where the amount of skin needed is greater than the recipient can provide, such as in burn victims with extensive burns, skin from donors is used.

Donated skin is useful, even if not properly matched, since it provides temporary protection from infection while new skin grows. By the time the graft is rejected, new skin is present.