Randomized Study In Severe Aplastic Anemia Patients Receiving Atg, Cyclosporin A, With Or Without G-CSF (SAA-G-CSF)

Inclusion Criteria: * Severe or very severe aplastic anemia * Less than 6 months from diagnosis of severe aplastic anemia by bone marrow biopsy * Ethical - Before randomization is done the subject or legally acceptable representative must give written informed consent for participation in the study Exclusion Criteria: * Eligibility for an HLA-matched sibling donor transplant * Prior therapy with ATG * Cyclosporin A \<4 weeks before enrollment * Treatment with G-CSF \<2 weeks before enrollment * Other growth factors \<4 weeks before enrollment * Diagnosis of Fanconi anemia, dyskeratosis congenita or congenital bone marrow failure syndrome * Evidence of myelodysplastic disease * Diagnosis or previous history of carcinoma (except local cervical, basal cell, squamous cells, or melanoma) * Subjects who have infection, hepatic, renal cardiac, metabolic or other concurrent diseases of such severity that death is imminent * Subject is pregnant (e.g. positive HCG test) or is breast feeding