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 (G-CSF PMRD)

Inclusion Criteria: Patients with hematologic malignancies or bone marrow failure syndrome who are candidates for allogeneic bone marrow transplantation are eligible for this study. Hematologic malignancies indicated for transplantation: Acute lymphoblastic leukemia (ALL) in first remission (with high risk feature), 2nd or greater remission. Acute myeloid leukemia (AML) in first remission (with high risk feature), 2nd or greater remission. Chronic myeloid leukemia (CML) in 2nd chronic phase or accelerated phase. Juvenile myelomonocytic leukemia (JMML). Myelodysplastic syndrome. Biphenotypic leukemia in first (with high risk feature), 2nd or greater remission. Induction failure leukemia. Refractory relapsed leukemia. Bone marrow failure syndrome. Severe aplastic anemia failed immunotherapy. Patients who do not have a 6 out of 6 matched related or unrelated donor or 4/6 and 5/6 matched cord blood will be eligible for this study. Partially mismatched related donor availability as defined by molecular typing with 3 to 5 HLA matches. Patients who are under 22 years of age. Exclusion Criteria: Patients will not be excluded based on sex, racial, or ethnic background. Patients will be excluded if they demonstrate significant functional deficits in major organs, which would obviously interfere with successful outcome following bone marrow transplant utilizing the following guidelines. Evidence of active, deep-seated, life-threatening infections for which there is no known effective therapy (certain fungal species, HIV, etc.). Patients who have been treated for infections must have appropriate responses as documented by 2 (two) consecutive negative cultures and/or stable radiographic examinations. Patients who have active central nervous system (CNS) leukemic disease. Patients will be excluded if they are women of childbearing potential who are currently pregnant (beta-HCG+) or who are not practicing adequate contraception. Patients who have had a previous hematopoietic stem cell transplant will be excluded. Donors will be excluded if they are sensitive to E. coli-derived protein.