Types of stem cells: From embryos to adults

Published: April 24, 2005
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Although they’re not a cure for any condition, stem cells can assist in the treatment of certain conditions. Despite the fact that stem cell research is still in its relative infancy, doctors have used stem cells in bone marrow transplants for more than 30 years. Bone marrow contains blood-forming stem cells. These cells continuously produce oxygen-carrying red blood cells, white blood cells that help fight infection and platelets that help stop bleeding. Bone marrow and stem cell transplants help treat certain cancers, such as leukemia and lymphoma, and some noncancerous conditions, such as aplastic anemia and some inherited immune disorders. Researchers are also investigating their use in some breast and ovarian cancers.

The chemotherapy and radiation used to treat these diseases can destroy bone marrow, leaving your body unable to produce the new blood cells you need to carry oxygen throughout your system and to fight infections. Stem cell transplants — though not a cure for the cancer itself — provide you with new cells that can regenerate the bone marrow.

The first bone marrow transplants gave bone marrow from a healthy relative to a person affected by a bone marrow disease. These transplants, called allogeneic transplants, are riskier than are transplants using the person’s own bone marrow. More recently, for some diseases, bone marrow transplants have used a person’s own marrow after it is removed from bone, treated and frozen. Chemotherapy and radiation treatments destroy the cancer cells or defective material in the removed marrow, and the remaining healthy marrow is transplanted back into the individual. Today, the treatment commonly involves using blood — as some stem cells also circulate in the bloodstream — rather than marrow. This is known as Peripheral blood stem cell transplantation.