What is a bone marrow transplant?
A bone marrow transplant can be used to:
- Replace diseased, nonfunctioning bone marrow with healthy functioning bone marrow (for conditions such as leukemia, aplastic anemia, and sickle cell anemia).
- Regenerate a new immune system that will fight existing or residual leukemia or other cancers not killed by chemotherapy or radiation.
- Replace bone marrow and restore its normal function after high doses of chemotherapy or radiation are given to treat a malignancy.
- Replace bone marrow with genetically healthy functioning bone marrow to prevent further damage from a genetic disease process (such as Hurler's syndrome and adrenoleukodystrophy).
Stem cells are primarily located in four places - an embryo, bone marrow, peripheral blood (found in blood vessels throughout the body) and cord blood (found in the umbilical cord and collected after the baby's birth). Stem cells for transplantation are obtained from any of the latter three sources.
Hematopoietic stem cell transplantation involves the intravenous infusion of stem cells collected from bone marrow, peripheral blood, or umbilical cord blood to re-establish hematopoietic function in patients whose bone marrow or immune system is damaged or defective.
More than 50,000 first hematopoietic stem cell transplantation procedures, 28,000 autologous transplantation procedures, and 21,000 allogeneic transplantation procedures are performed every year worldwide, per the first report of the Worldwide Network for Blood and Marrow Transplantation.
This number continues to increase by 10-20% annually, and reductions in organ damage, infection, and severe, acute graft versus host disease (GVHD) seem to be contributing to improved outcomes. In a study of 854 patients who had survived at least 2 years after autologous hematopoietic stem cell transplantation (HSCT) for hematologic malignancy, 68.8% were still alive 10 years after transplantation.
A number of diseases, many of which are incurable, pose a threat to bone marrow. They prevent bone marrow from turning stem cells into essential cells. Leukemia, Hodgkin's disease, and other lymphoma cancers are known to damage the marrow's productive ability and destroy stem cells.
The leading treatment for conditions that threaten bone marrow's ability to function is a bone marrow transplant. A bone marrow transplant is used to rebuild the body's capacity to produce blood cells and bring their numbers to normal levels. Illnesses that may be treated with a bone marrow transplant include both cancerous and noncancerous diseases.
Cancerous diseases may or may not specifically involve blood cells, but cancer treatment can destroy the body's ability to manufacture new blood cells. This procedure typically begins with chemotherapy to eliminate the compromised marrow. A matching donor, in most cases a close family member, then has their bone marrow harvested and readied for transplant.