Bone marrow has a very special type of blood cell called a stem cell .
These very special cells grow into mature blood cells in the bone marrow and are then released into the blood stream. These are the life-giving cells transplanted into many patients that have diseases of the blood during a bone marrow transplant. When the physician decides a patient needs a transplant, they will choose the source of stem cells, either from marrow or PBSC, that they believe will be best for the patient. Marrow Harvest Traditionally, stem cells have been donated from one individual to another by a simple procedure performed in day surgery. In this procedure, the collection center physician collects the marrow by putting a sterile needle into the back of the pelvic bone.