Stem cell transplant
Stem cell or bone marrow transplant
Traditionally, the term bone marrow transplantation has been used to describe the process of taking cells from a person's bone marrow and re-infusing them following high doses of chemotherapy or radiation therapy.
Stem cells dividing in the bone marrow are responsible for the production of red and white blood cells and platelets. They also circulate in the blood in small numbers. Chemotherapy is a common treatment for patients with these diseases but the drawback is that normal cells are usually killed along with the remaining malignant cells. To overcome this, stem cells are collected prior to treatment and infused into the patient after chemotherapy. These stem cells home in and grow in the bone marrow cavity, and produce new red blood cells, white blood cells and platelets.
There are recent developments in transplantation, called mini, or non-myeloablative transplantation, where the initial chemotherapy dose is reduced. This minimises the toxicity associated with the treatment and means that older patients may be treated safely with this technique.
The stem cells are important wherever they are collected, either in the blood where they travel, or in the bone marrow where they rest and divide. They can be collected in a variety of ways from a variety of different donors.
Sources of stem cells
Bone marrow: Stem cells can be collected from the bone marrow of a donor. This requires the donor to have a general anaesthetic so that cells can be collected by multiple needle punctures from the hip bone or sternum.
Peripheral blood: Stem cells can be found in normal blood in very small numbers. Following chemotherapy and/or treatment with a bone marrow stimulant called G-CSF, the stem cells leave the bone marrow in increased numbers and enter the peripheral blood. There they can be collected by a special harvesting technique using a cell separator machine.
Umbilical cord blood: The umbilical cord blood is normally discarded when a baby is born. It is a rich source of stem cells. These can be extracted from the discarded cord after the delivery of a baby, stored permanently and be a source of bone marrow. This process does not represent a risk to the baby or mother.
Donors of stem cells
Autologous: The patient's own stem cells. These are collected when the patient is in remission. (Auto = oneself)
Allogenic: From donor stem cells. The donor can be a sibling or unrelated. Stem cells can be collected from volunteers who have signed up with one of the many bone marrow or cord blood registries located worldwide. Compatible donors are found by searching the database of registered donors.
These procedures are not suitable for everyone and represent a major undertaking for doctors, nurses and families and a major risk to the patient. However, when possible, transplantation offers the best known opportunity of a cure for many diseases.
For more information on transplants, please contact lbf@leukaemia.org.nz or 0800 15 10 15. We will soon have two new titles available in our information booklet series - Allogeneic stem cell transplants and Autologous stem cell transplants.