Tissue transplantation is the removal of various tissues, such as skin cells, corneas, cartilage, or bone, from a body and then inserting that tissue into the same or another person who has a serious disorder affecting some of that type of tissue.
(See also Overview of Transplantation.)
Skin
Skin grafts are considered a form of transplantation. Skin grafts can be used in people who have lost large areas of skin—for example, because of extensive burns. Skin grafting is most successful when healthy skin is removed from one part of a person's body and grafted to another part. When such grafting is not possible, skin from a deceased donor or even from animals (such as pigs) or synthetic skin can be used as a temporary measure. Such grafts last only a short time, but they can provide temporary protection until normal skin grows to replace them.
The amount of skin available for grafting may be increased by growing small pieces of the person’s skin in a tissue culture or by making many tiny cuts in the grafted skin, so that it can be stretched to cover a much larger area.
Cartilage
Cartilage is usually used to repair birth defects in the ears or nose of children. In adults, it can be used to repair joints damaged by injury or by arthritis.
Cartilage may be transplanted successfully without the use of drugs to suppress the immune system (immunosuppressants). The body’s immune system attacks transplanted cartilage much less vigorously than other tissues.
Corneas
Corneas, the transparent domes on the surface of the eyes, can usually be transplanted successfully without the use of immunosuppressants.
Bone
Bone from one part of the body can be used to replace bone in another part—for example, to replace bone removed during surgery for bone cancer.
Bone transplanted from one person to another survives only a short time. However, it stimulates growth of new bone, stabilizes the area until new bone can form, and provides a framework for new bone to fill in.
Immunosuppressants are not needed after bone transplantation.
More than one tissue
Some transplants contain more than one tissue (called composite transplants, such as hand, arm, or face transplants). Composite transplants may include skin, muscle, bone, and tissues that connect and support these structures.
Composite transplantation is controversial because it typically is not needed to preserve life and does not extend it, although it may greatly improve quality of life. Composite transplantation is also very expensive, requires many resources, and may result in sometimes life-threatening infections. These procedures are not considered standard medical care.
How well the transplanted parts function varies widely, but some recipients of a hand transplant are able to use the hand to do their usual daily activities.
Immunosuppressants are required after transplantation.
Other tissues
In Parkinson disease, transplanting tissue from a person’s adrenal glands to that person’s brain appears to relieve symptoms, as does transplanting brain tissue from aborted fetuses. However, use of tissue from aborted fetuses is controversial.
Transplantation of thymus glands from stillborn infants into children who are born without a thymus gland (a disorder called DiGeorge syndrome) may help restore the immune system in these children. When the thymus gland is missing, the immune system is impaired because white blood cells, which are a vital part of the immune system’s defense against foreign substances, mature in the thymus gland. However, the new thymus may produce cells that attack the recipient’s cells, causing severe graft-versus-host disease (see also video The Thymus and T cells).
Transplantation of the uterus can sometimes be done in women who want to become pregnant but have an abnormal uterus or have previously had their uterus removed.
