What happens in a bone marrow transplant

To test the compatibility of a donor’s marrow with a patient’s marrow, a small sample of blood is drawn from the potential donor and patient. A human leucocyte antigen (HLA) tissue typing test is performed to determine if the antigens or markers on the white blood cells of the donor match those on the patient’s white blood cells.

Each person’s bone marrow has distinct genetic characteristics, half of which are inherited from their mother, the other half from their father. A patient with an identical twin has a ready made donor of perfectly matched bone marrow. Many however, will need to find another person related or unrelated, whose bone marrow matches their own.

In a bone marrow transplant, the patient’s diseased bone marrow is destroyed and healthy marrow is infused into the patient’s bloodstream. In a successful transplant the new bone marrow migrates to the cavities of the large bones, engrafts and begins producing normal blood cells.

The new bone marrow infused into the patient must match the genetic makeup of the patient’s own marrow as perfectly as possible. If the new bone marrow is not a good match, it will recognize the patient’s body as foreign material to be attacked and destroyed. This condition is known as graft versus host disease (GvHD), and can be life threatening.

When is a transplant possible

A successful transplant not only requires matched bone marrow but a patient who is healthy enough to undergo the transplant procedure. A medical physician will determine whether a patient should undergo a transplant, by examining the patient’s

• general physical condition
• diagnosis, and
• the stage of the disease

After the patient’s marrow has been destroyed, healthy marrow is infused into the patient’s bloodstream over several hours. Unlike other transplants, a bone marrow transplant is performed in the patient’s hospital room.

It may take 3 to 4 weeks for the new bone marrow to engraft and begin producing healthy blood cells. The patient remains in the hospital until a sufficient number of healthy new red blood cells, white blood cells, and platelets are being produced by the new bone marrow. It usually takes 4 to 8 weeks before the patient’s immune system is able to defend itself against infection and bleeding.

Complications a bone marrow recipient can experience

In addition to the side effects caused by chemotherapy and irradiation such as nausea, vomiting, hair loss, diarrhoea, and poor appetite, there are several complications that may result from the transplant. These include:

• rejection
• Graft versus host disease (GvHD)
• infection, and
• relapse

To locate your nearest transplant centre, take a look at the pages adult and paediatric transplant centres.