There are several reasons for doing a bone marrow transplant (BMT). The procedure can provide normal bone marrow to patients:
- Whose own bone marrow stem cells are abnormal or defective.
- Whose own bone marrow has been destroyed by chemotherapy and radiation therapy in order to treat cancer.
- With a genetic disease that affects all of the organs in the body.
Stem Cells Defects
Some children are born with defects in bone marrow stem cells, while other children develop these defects later in life. When one or a combination of these cells is abnormal it usually results in a fatal disease such as:
- Aplastic anemia
- Thalassemia major
- Sickle cell disease
- Severe combined immunodeficiency disease (SCID)
- Wiskott-Aldrich syndrome
- Fanconi's anemia
- Chronic granulomatous disease
A transplant using healthy bone marrow stem cells from a donor is the preferred treatment for these diseases.
Cancer
Bone marrow transplantation may be used to treat:
- Leukemia
- Lymphoma
- Neuroblastoma
- Medulloblastoma
- Sarcoma
The treatment for these conditions uses high doses of chemotherapy and sometimes radiation therapy to kill all of the cancer cells in the body. However, this also kills the healthy marrow cells.
Bone marrow stem cells for the transplant come either from a healthy donor or from the patient. When using stem cells from the patient, the bone marrow or peripheral blood stem cells are collected, processed in the laboratory, frozen and stored for future use prior to chemotherapy and radiation therapy.
Following the administration of large doses of chemotherapy and sometimes radiation therapy, the stem cells are thawed and administered to the patient. Sometimes the autologous bone marrow stem cells are treated with drugs in order to selectively kill or remove any remaining cancer cells that may be present.
Genetic Diseases
Certain inherited diseases also may be treated with bone marrow transplantation. In some instances, only the marrow stem cells are affected, for example:
- Severe combined immunodeficiency disease (SCID)
- Thalassemia major
- Sickle cell disease
However, in many of the genetic diseases, there is a defect in the way chemicals are processed in the body that affects many organs including the heart, lungs, liver, kidneys, bones and usually the brain. This is the case with diseases such as:
- Hurler's syndrome
- Fanconi's syndrome
- Adrenoleukodystrophy
- Metachromatic leukodystrophy
With these conditions, the bone marrow cells may or may not be affected. The purpose of the bone marrow transplant for these diseases is to provide healthy cells from the donor that travel to the various organs in the body and correct the chemical imbalance.
For some of the genetic diseases, such as Hurler's syndrome, metachromatic dystrophy, osteopetrosis and Fanconi's syndrome, a bone marrow transplant has been proven to be effective. For others, the benefit is not as clear and more studies are needed.
