A bone marrow transplant is a procedure that transplants healthy bone marrow into a patient whose bone marrow is not working properly.

Bone marrow is a soft, fatty tissue inside the bones. This is where blood cells (red blood cells, platelets, and white blood cells) are produced, and develop.

In some diseases of the blood cells -- especially cancers such as leukemia -- high doses of chemotherapy may be needed to destroy the cancer. However, this also destroys normal bone marrow and prevents it from making enough blood cells.

In other cases in which hereditary or acquired disorders cause abnormal blood cell production, a transplant of healthy bone marrow may correct these problems. Transplanted bone marrow will restore production of white blood cells, red blood cells, and platelets.

Bone marrow transplant patients are usually treated in specialized centers. The patient stays in a bone marrow transplant unit, or BMT, to limit exposure to infections.

The healthy bone marrow may be taken from the patient before chemotherapy or radiation treatment (autograft). Or, it may be taken from a donor (allograft). The donor can be a relative (usually a brother or a sister), or an unrelated person (found through the national marrow donor program).

Donated bone marrow must match the patient's tissue type. Donors are matched through special blood tests called HLA tissue typing (see HLA antigens).

Bone marrow is taken from the donor in the operating room while the donor is unconscious and pain-free (under general anesthesia). Some of the donor's bone marrow is removed from the top of the hip bone. The bone marrow is filtered and treated. It can be transplanted immediately or frozen and stored for later use.

Transplant marrow is given to the patient through a vein (IV). It is naturally carried into the bone cavities, where it grows to replace the old bone marrow.

The patient is prepared for transplant by getting high doses of chemotherapy or radiation (conditioning). This serves two purposes:

• It destroys the patient's abnormal blood cells or cancer.
• It slows the patient's immune response against the donor bone marrow (graft rejection).

Following conditioning, the patient is ready for bone marrow infusion. After infusion, it takes 10 - 20 days for the bone marrow to establish itself. During this time, the patient will need support with blood cell transfusions.

Bone marrow transplant may be recommended for:

• Bone marrow deficiency disease caused by:
  • Abnormal red blood cell production, such as thalassemia or sickle cell disease
  • Aggressive cancer treatments (chemotherapy, radiation therapy), especially for leukemia or lymphoma
  • Lack of normal blood cell production (aplastic anemia)
• Immune system disorders (immunodeficiencies) such as:
  • Congenital neutropenia
  • Severe combined immunodeficiency syndrome
• Specific forms of cancer:
  • Leukemias
  • Lymphomas
  • Myeloma

Bone marrow transplant is not recommended for patients with:

• Heart, kidney, lung, or liver disorders
• Other diseases that may limit survival

The risks for any anesthesia are:

• Problems breathing
• Reactions to medications

Chemotherapy given before the bone marrow transplant (conditioning) may cause side effects such as:

• Diarrhea
• Liver damage
• Lung damage
• Mouth sores

While waiting for bone marrow to grow, the patient is at high risk for infections. Although the risk lowers over time, the person will have an increased risk of getting serious infections for years after a bone marrow transplant.

The major problem with bone marrow transplants when the marrow comes from a donor is graft-versus-host disease. The transplanted healthy bone marrow cells may attack the patient's cells as though they were foreign bodies. In this case, the patient must take drugs to suppress the immune system. However, these drugs also decrease the body's ability to fight infections.

Ideally, a bone marrow transplant lengthens the patient's life.

After a transplant, you can go back to most of your normal activities as soon as you feel well enough. Talk to your doctor first, however.

Other problems with a bone marrow transplant are those of all major organ transplants -- finding a donor, and paying for the transplant. The donor is often a sibling with matching tissue. The more siblings the patient has, the more chances there are of finding a matching donor.

You will be in the hospital for 4 - 6 weeks. During this time, you will be isolated and under strict monitoring because of the increased risk of infection.

You will need attentive follow-up care for 2 - 3 months after being released from the hospital. It takes 6 months to more than a year for the immune system to fully recover from this procedure. Some people do not fully recover.

Vose JM. Bone marrow transplantation. In: Abeloff MD, Armitage JO, Niederhuber JE, Kastan MB, McKenna WG. Abeloff: Clinical Oncology. 3rd ed. Philadelphia, Pa:Churchill Livingstone;2004:chap 28.

Vose JM, Pavletic SZ. Hematopoietic stem cell transplantation. In: Goldman L, Ausiello D. Goldman: Cecil Medicine. 23rd ed. Philadelphia, Pa: Saunders Elsevier;2007:chap 184.