A bone marrow transplant is when stem cells that are normally found in the bone marrow are taken out of a donor, and given to another person. Umbilical cord blood is another rich source of stem cells and can also be used for the transplant.
Why Is It Done?
Bone marrow produces stem cells. These stem cells eventually develop into blood cells. Bone marrow is a critical part of the body because it is the body’s main blood cell “factory.” The purpose of a bone marrow transplant is to put healthy stem cells in place of the unhealthy ones. This can treat the symptoms of alpha-mannosidosis, by transplanting Luke with donor stem cells that will make the enzyme that Luke is missing.
An allogenic bone marrow transplant is when the donor is another person whose tissue has the same genetic type as the person needing the transplant (recipient). Because tissue types are inherited, similar to hair or eye color, it is more likely that the recipient will find a suitable donor in Luke’s brother Andrew. This, however, happens only 25 percent of the time.
If Andrew or another family member does not match the recipient, the National Marrow Donor Program Registry database is searched for an unrelated individual whose tissue type is a close match. It is more likely that a donor who comes from the same racial or ethnic group as the recipient will have the same tissue traits.
Sources of Bone Marrow Stem Cells
- Bone marrow harvest: Collecting stem cells by taking them directly out of the bone.
- Apheresis: Collecting stem cells by filtering the blood for peripheral (circulating) blood cells (PBSC).
- Umbilical cord blood: Stem cells are filtered from blood in the umbilical cord after a baby is born.
What the Donor Experiences
In most cases, a donation is made using circulating stem cells (PBSC) collected by apheresis. First, the donor receives injections for a few days of a medication that causes stem cells to move out of the bone marrow and into the blood. For the stem cell collection, the donor is connected to a machine by a needle inserted in the vein (like for blood donation). Blood is taken from the vein, filtered by the machine to collect the stem cells, then returned back to the donor through a needle in the other arm. There is almost no need for a recovery time with this procedure.If stem cells are collected by bone marrow harvest (much less likely), the donor will go to the operating room and while asleep under anesthesia, a needle will be inserted into either the hip or the breastbone to take out some bone marrow. After awakening, he/she may feel some pain where the needle was inserted.
What the Recipient Experiences
Bone marrow transplant is a difficult procedure to go through. Usually the person receives high doses of chemotherapy and/or radiation to eliminate whatever bone marrow he/she has left and make room for the new marrow transplant. Once this is done, the new stem cells are put into the person intravenously, like a blood transfusion. The stem cells will then find their way to the bone and start to grow and produce more cells (called engraftment).Serious problems can occur during the time that the bone marrow is gone or very low. Infections are common, as is anemia, and low platelets in the blood can cause dangerous bleeding internally. Recipients often receive blood transfusions to treat these problems while they are waiting for the new stem cells to start growing.