Leukemia is a cancer of white blood cells, or leukocytes. Like other blood cells,
leukocytes develop from somatic stem cells. Mature leukocytes are released into the
bloodstream, where they work to fight off infections in our bodies.
Leukemia results when leukocytes begin to grow and function abnormally, becoming
cancerous. These abnormal cells cannot fight off infection, and they interfere with
the functions of other organs.
Successful treatment for leukemia depends on getting rid of all the abnormal leukocytes
in the patient, allowing healthy ones to grow in their place. One way to do this is through
chemotherapy, which uses potent drugs to target and kill the abnormal cells. When
chemotherapy alone can't eliminate them all, physicians sometimes turn to bone marrow transplants.
In a bone marrow transplant, the patient's bone marrow stem cells are replaced with those
from a healthy, matching donor. To do this, all of the patient's existing bone marrow and
abnormal leukocytes are first killed using a combination of chemotherapy and radiation. Next,
a sample of donor bone marrow containing healthy stem cells is introduced into the patient's bloodstream.
If the transplant is successful, the stem cells will migrate into the patient's bone marrow
and begin producing new, healthy leukocytes to replace the abnormal cells.
New evidence suggests that bone marrow stem cells may be able to differentiate into cell
types that make up tissues outside of the blood, such as liver and muscle. Scientists are
exploring new uses for these stem cells that go beyond diseases of the blood.