Matching
For some to donate their bone marrow, their cells have to be similar to those of the recipient. In order to match up donors and recipients, physicians look at a series of molecules that are found on the surface of the blood cells called HLA antigens. These molecules vary from person to person. The more similar the donor's HLA antigens are to the recipient's, the more likely the bone marrow transplant will be a success. As a result, if a patient needs a bone marrow transplant, doctors will often screen his relatives to see if they could serve as potential donors. Sometimes the patient will actually receive the bone marrow from herself if doctors are able to harvest her bone marrow in advance.
Bone Marrow Harvest
There are two different ways in which the bone marrow stem cells can be harvested from the donor. One procedure is called apheresis, which runs the donor's blood through a machine that is able to filter out the stem cells, which are then saved for the actual transplant. This treatment often requires multiple sessions. Alternatively, doctors can harvest the bone marrow stem cells by inserting a needle into the donor's bone marrow (which is the soft part of the bone). The hip bones and the sternum are the sites that are most commonly used for a bone marrow harvest. The donor will be anesthetized during the procedure and will not feel any pain while his bone marrow is being harvested.
Transplant
The transplant process typically begins with the recipient receiving high doses of radiation or chemotherapy to kill off the cells in the recipient's bone marrow. This gives the donor cells space to live and reproduce within the recipient's bones. After this, the recipient is given the stem cells via a central venous catheter, which allows the stem cells to be rapidly spread throughout the body. The stem cells will then naturally migrate to the bone marrow and take up residence there, where they will make new blood cells. Afterward, the recipient will need to be monitored to see if her immune system is attacking the transplant and to ensure that she does not develop any infections while she is recovering.
