I’ve talked frequently about bone marrow transplants, and now it's time to take a step back and explain what this life-saving procedure is all about.
Bone marrow transplants are used to treat patients with leukemia and lymphoma, severe blood diseases and certain immune-deficiency diseases that prevent the body from making some types of white blood cells.
In the case of cancers, high doses of chemotherapy and sometimes radiation severely damage or destroy damaged bone marrow, and the transplant replenishes it.
Many people have heard of the controversies surrounding the use of embryonic stem cells in research. These cells are different and are not found in the bone marrow.
Stem cells are the undifferentiated cells that develop into any of the more than 200 types of cell in an adult body. The term bone marrow transplantation is used interchangeably with stem-cell transplant.
There are two kinds of transplant: autologous and allogeneic.
Autologous transplants involve removing a patient's own new, clean stem cells after repeated rounds of chemotherapy have eradicated the leukemia, then returning them to replenish the bone marrow after a final, stronger round of chemotherapy wipes it out.
Allogenic transplants can be compared to a solid organ transplant. They come with side effects absent in an autologous transplant, but they also can have more of an ongoing therapeutic value.
In the early days of transplant, bone marrow was collected directly from a donor's pelvis. This procedure is used less frequently now because it must be done in a hospital using local or general anesthesia. For this procedure, a hollow needle is inserted repeatedly into the pelvis, and marrow is sucked out of the bone.
The other way is through a procedure called apheresis, in which a needle is placed in the donor's arm to draw blood. Then, his or her blood is passed through a machine that removes the stem cells from the blood. The rest of the blood is returned to the donor. The process is the same for patients who donate their own stem cells.
When a pioneering doctor, E. Donnall Thomas, began his research in the late 1950s, bone marrow transplants were seen as a frightening last resort. The patient’s immune system would either destroy the transplanted marrow as foreign, or the transplanted marrow, which contains immune system cells, would destroy the patient’s lungs, kidneys, and other organs.
Thomas learned to match tissue types between recipients and donors and to use drugs to tamp down the immune system. His team carried out its first transplant using a matched sibling donor for a patient with leukemia in 1969. Eight years later, the team performed the first matched transplant from an unrelated donor, a success that led to the formation of a national registry that now includes more than 11 million marrow donors.
It takes only a tongue swab for potential donors be typed for the genetic markers called human leukocyte antigens (HLA) that need to be a close match for recipients.
Those between the ages of 18 and 60 may register to donate either on line by requesting a kit or through donor drives. More information is available here
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