All of the blood cells in your body start out as young (immature) cells called hematopoietic stem cells. (Hematopoietic means blood-forming.) Even though they may be called “stem cells” for short, these cells are not the same as stem cells from embryos that are studied in cloning and other types of research. Here, we will use “stem cells” to mean hematopoietic stem cells.
Stem cells mostly live in the bone marrow (the spongy center of certain bones), where they divide to make new blood cells. Once blood cells are mature they leave the bone marrow and enter the bloodstream. A small number of stem cells also get into the bloodstream. These are called peripheral blood stem cells.
Stem cell transplants are used to restore the stem cells when the bone marrow has been destroyed by disease, chemotherapy (chemo), or radiation. Depending on the source of the stem cells, this procedure may be called a bone marrow transplant, a peripheral blood stem cell transplant, or a cord blood transplant. We will give you more detail on each of these later. Any of these types may be called a hematopoietic stem cell transplant.
