Allogeneic Stem Cell Transplant

Treatment Overview

What is a stem cell transplant?

Most stem cells are in your bone marrow. You also have some that circulate from your marrow into your blood. Bone marrow stem cells turn into red blood cells, white blood cells, or platelets to help your body stay healthy. If your bone marrow is damaged or destroyed, it can no longer make normal blood cells. In a stem cell transplant, healthy stem cells are placed in your body through an IV to help your bone marrow start to work right.

When the stem cells come from another person, it is called an allogeneic transplant. The donor may be a relative or a complete stranger. The important thing is that the donor's immune system markers are closely matched to yours. This is more likely when the donor is your brother or sister.

When the stem cells come from your own blood or bone marrow, it is called an autologous transplant.

Stem cells can also be found in your bloodstream and in the blood inside a newborn's umbilical cord.

When is a stem cell transplant needed?

Doctors use stem cell transplants to:

• Treat diseases that damage or destroy the bone marrow, such as non-Hodgkin's lymphoma and Hodgkin's lymphoma, leukemia, multiple myeloma, and aplastic anemia.
• Restore bone marrow that has been damaged by total body radiation and high doses of chemotherapy used for cancer treatment.

Other uses for stem cells are being studied, such as the treatment of immune system defects, diabetes, sickle cell disease, and thalassemia.

How do you know if you are a good candidate for a stem cell transplant?

Your doctor will consider your health and your age. People who are good candidates usually are younger than 70, do not have other diseases such as heart disease or diabetes, and have a normal kidney and liver. Your doctor will also consider how much your disease has grown and how aggressive your cancer is. People with aggressive cancer that has spread to many areas of the body are not usually good candidates. Your doctor may also consider if you have cancer that has come back, such as relapsed non-Hodgkin's lymphoma or leukemia.

How are stem cells collected?

It depends on where the stem cells come from.

For bone marrow transplantation (BMT), a small amount of the liquid portion of the bone marrow is removed through a needle inserted into the bone. This is done many times to collect enough stem cells for the person receiving the donated bone marrow. This is called harvesting the bone marrow. The bone marrow cells are put into a blood bag. They are often frozen for future use.

For peripheral blood stem cell transplantation (PBSCT), stem cells are taken from blood. The growth factor G-CSF may be used to stimulate the growth of new stem cells so they spill over into the blood. G-CSF is a protein that is produced naturally in the body. The blood is removed from the vein and passed through a machine that takes out the stem cells. The machine then returns the remaining blood through a needle in the person's arm or through a central venous catheter. This way of collecting stem cells is called apheresis.

Stem cells may also be taken from umbilical cord blood. This is something that must be arranged with a blood bank before a baby's birth.

Why are chemotherapy and radiation therapy used before a transplant?

Doctors use chemotherapy and radiation to destroy your bone marrow. This also gets rid of the cancer cells-along with the normal cells-in your bone marrow and the rest of your body. Later, when you get healthy stem cells from a donor, those new cells will go to the marrow and be able to take over the job of making new blood cells.

How are stem cells transplanted?

A central venous catheter is inserted into your chest. The stem cells travel through the catheter into your blood, and to your bone marrow, where they will begin to produce new cells in 1 to 3 weeks. During this time:

• You may be in isolation and given antibiotics to prevent or treat infection. Because the chemotherapy destroys your white blood cells, your body will not be able to fight infection until it starts making new white blood cells.
• Your blood will be tested often to check the levels of red blood cells, white blood cells, and platelets in your body.
• You may need to receive several transfusions of blood cells and platelets until your body begins to produce its own.
• You may need more antibiotics or other medicines if you get an infection.

Who can donate stem cells?

Healthy adults ages 18 to 60 can donate stem cells. Children may be donors for themselves or a brother or sister. In some cases, people who are older than 60 can donate.

If you wish to be a stem cell donor, a blood sample is taken from you and tested for tissue type. It is then compared with the tissue types of people needing a transplant. If a match is found, another blood sample will be drawn to see if your tissue type matches well enough for the transplant.

If you are selected as a stem cell donor, you will have a complete physical exam. You will also be asked questions about your health and your family history of diseases. You will also be asked to sign a consent form to have the procedure.

If you are a stem cell donor, you will receive injections of a drug called filgrastim for several days. (It is also called G-CSF, for "granulocyte colony-stimulating factor.") Filgrastim is a drug that helps your body move more white blood cells out of your bone marrow and into your bloodstream. Blood will be removed from your arm, sent through a machine to remove the stem cells, and returned to your bloodstream through your other arm.

The bone marrow collection process is a surgical procedure done under a local or general anesthetic. The procedure takes 1 to 2 hours. Bone marrow is usually removed from the back of your pelvic bone using sterile needles.

What about umbilical cord blood banking?

Umbilical cord blood banks have been established in some areas of the United States, Canada, and many countries in Europe to supply stem cells for related and unrelated people. Using blood from these banks decreases the time it takes to search for a match, because the samples are already typed for genetic information (HLA) and blood group and treated for infection. The match does not need to be as specific as it does with bone marrow or peripheral stem cells. Umbilical cord blood transplants also cause fewer problems with graft-versus-host disease.