Bone marrow itself is the sponge-like tissue found inside your large bones, and makes the blood cells in your body. This cell-making function of bone-marrow is essential to your body's vital functions and your body's ability to fight infection, so any changes to your bone marrow require extreme caution.

The bone marrow cells can be harvested from you in two ways, depending on the type of transplant being done. One method involves a one-time visit to the operating room, where you are given general anesthesia and the doctors remove the marrow by placing needles into the hip bone and withdrawing some of the bone marrow. This entire procedure takes one to two hours. You will be awake and alert in the evening of the same day. There will be some soreness, but pain medication will be given if needed.

The other method collects bone marrow cells from the circulating blood system. This procedure is similar to having blood drawn, and the only discomfort the donor may feel is when the needles are inserted. This is done on an outpatient basis. Usually three to five procedures are needed to get enough cells for a transplant.