 Our initial trials in the 1980s with T-cell depleted transplants showed less GvHD, but the overall results of the transplants were not better. The reason for this was that the stem cells did not take and engraft in 15 of our adult patients. This failure of the stem cells to take can leave patients without bone marrow or blood cells necessary for life. Most stem cell transplants were done using bone marrow BMA obtained from the donors. However, if we give a medication called G-CSF by shots to the donor, we can collect peripheral blood stem cells PBSC and use them for transplant. The advantage of this approach is that we can collect 2-20 times more stem cells than that obtained from the marrow. It has been proven that a larger number of stem cells in the graft make it more difficult for the patient to reject the stem cells. Some donors may be too small to provide peripheral blood stem cells or they may not want to take G-CSF shots. In these cases the donors will have their marrow collected in the operating room under general anesthesia. 