Myeloablative Conditioning, Prophylactic Defibrotide and Haplo AlloSCT for Patients With Sickle Cell Disease

This is a follow-up trial to NYMC 526 (NCT01461837) to assess the safety, efficacy and toxicity of administering Defibrotide prophylaxis for high-risk sickle cell or beta thalassemia patients undergoing a familial haploidentical or MUD allogeneic stem cell transplantation with CD34 enrichment and T-cell addback. This patient population historically has a risk of developing sinusoidal obstructive syndrome (SOS) and Defibrotide has demonstrated efficacy in treatment of SOS. The Funding Source is FDA OOPD.

Inclusion Criteria: * Disease: Homozygous Hemoglobin S Disease, or Hemoglobin S B0/+ thalassemia, or Hemoglobin SC Disease, or Beta thalassemia intermedia/majora * Patients must demonstrate one or more of the following Sickle Cell Disease Complications * Clinically significant neurologic event (stroke) or any neurologic deficit lasting \>24 hours that is accompanied by an infarct on cerebral MRI * Acute chest syndrome in the preceding two year period prior to enrollment that have failed, been non-compliant or declined hydroxyurea treatment, or prior to chronic RBC transfusion therapy, exchange transfusion or erythrocyte pheresis. * Recurrent painful events (at least 3 in the 2 years prior to enrollment or prior to chronic RBC transfusion therapy, exchange transfusion or erythrocyte pheresis). * Abnormal TCD study requiring starting on chronic transfusion therapy and/or exchange transfusions. * At least one silent infarct lesion on a MRI scan of the head. Or (directly or probably related to SCD) * Sickle Cell nephropathy; * Splenic sequestration requiring RBC transfusion; * Aplastic crisis requiring RBC transfusion; * Avascular necrosis of the hip diagnosed by MRI; * Two episodes or more of leg ulcerations; * Recurrent priapism . * Infant dactylitis. * all patients must meet disease, age, organ function and donor criteria; Exclusion Criteria: * Patients who are receiving concomitant systemic anticoagulants and/or fibrinolytic therapies. * Patients with a previously known hypersensitivity reaction to defibrotide. * Females who are pregnant or breast-feeding are not eligible * Patients with documented uncontrolled infection at the time of study entry are not eligible. * Patients who have an unaffected HLA matched sibling donor willing to proceed to donation will not be eligible for this study. * Karnofsky or Lansky (age appropriate) Performance Score \