Research studies have shown that patients with Aplastic Anemia have improved survival (may live longer) after receiving a HLA (Human Leukocyte Antigen) identical sibling (brother and sister) stem cell transplants. Patients who do not have matched siblings can undergo immunosuppressive therapy, which has also shown to improve outcome. Unfortunately patients who do not respond to immunosuppressive therapy usually die. The best chance of survival for these patients is an HLA matched unrelated or mismatched related stem cell transplant as described below.