Stem cells will be collected from both the patient and donor. To do this, the hormone G-CSF will be injected under the skin for several days to increase stem cell production. Then, the stem cells will be collected by apheresis. In this procedure the blood is drawn through a needle placed in one arm, pumped into a machine where the desired cells are separated out and removed, and then the rest of the blood is returned through a needle in the other arm.