Hematopoietic (blood-making) stem cell transplantation has
been performed for decades in patients with leukemias or other blood disorders,
being the only potentially curative therapy in many cases.  The concept behind
this procedure is that a dose of radiation and/or chemotherapy is first given to
the recipient in order to destroy their stem cells.  The radiation and/or
chemotherapeutic doses given are so high that if the patient was not