G-CSF PMRD: Granulocyte Colony Stimulating Factor (G-CSF) Stimulated Bone Marrow and In Vivo T-Cell Depletion in Patients With Hematologic Malignancies or Bone Marrow Failure Syndrome

This study is a single-arm, non-randomized feasibility study. Patients meeting the criteria for this study will be entered sequentially until completion or closure of the study. Early stopping rules will be employed to ascertain whether an unacceptable rate of toxicity (non-engraftment, and/or acute GVHD) occurs. Patients will be prepared for transplant through the administration of the following conditioning regimen based on their primary disease: * Total body irradiation (1400 rads in 8 fractionated doses) and high dose chemotherapy, including cytosine arabinoside, etoposide, and cyclophosphamide. Patients with bone marrow failure syndrome will not receive etoposide in the conditioning regimen. * Post transplant immunosuppression prophylaxis against acute GVHD will include sequential administration of cyclosporine, methotrexate, basiliximab and mycophenolate. * The donor will receive 3 daily G-CSF injections prior to marrow harvest starting on day -3. The injections may be initiated by the donor's primary physician prior to donor's arrival, or by the BMT service at Children's Healthcare of Atlanta. * Patients will receive daily GM-CSF injections (250 mcg/m2) starting from day +7 post transplant until absolute neutrophil count (ANC) is greater than 2,000/µL for three days.