Stem cells are very early, undifferentiated forms of cells that can develop into specialized blood cells. Stem cells can also quickly multiply to produce more stem cells.
One of the main sites where stem cells are found is within the shafts of long bones inside a tissue called bone marrow. This spongy tissue contains special stem cells which produce red blood cells (that carry oxygen in the blood), white blood cells (that help fight off infection) and platelets (that regulate bleeding and clotting functions).
A stem cell transplant or a bone marrow transplant is essentially the infusion or injection of healthy stem cells to replenish the blood in cases where stem cells are diseased or damaged. For this process, stem cells from healthy blood or bone marrow are injected or infused by way of a catheter into the patient’s vein. The transplanted cells then find their way to the bone marrow where they start producing supplies of healthy blood cells. It may take a few weeks for the healthy blood cells to be produced and for blood counts to start to normalise.
Stem cell transplants are useful in several conditions including:
Leukemias or cancer of the white blood cells
Lymphomas especially Non-Hodgkin’s lymphomas or cancer of the lymphatic system
Severe aplastic anemia where there is complete failure of the bone marrow
Other cancers such as multiple myeloma and other diseases such as sickle cell anemia
Types of stem cell transplant
There are three basic types of stem cell transplants, which are named according to who the cells for transplant are taken from.
An autologous stem cell transplant uses stem cells taken from the patient’s own body
An allogenic transplant uses cells obtained from a tissue-matched individual who may be related or unrelated to the patient.
A synergenic transplant uses cells obtained from an identical sibling.
Reviewed by Sally Robertson, BSc