Patient description: The patient is a 34-year-old African American man with the known history of Sickle cell disease comes to the clinic with severe bone pain. The patient had severe pain in his lower back that radiated to both thighs scored 9 out of 10. The patient has had positive history of sickle cell crises since childhood. He also had the same symptoms in past two weeks treated with oxycodone which was not beneficial to his pain. His PCP sent him to the emergency department to receive intra venous pain modulators. The patient is afebrile within the normal blood pressure. No splenomegaly was detected in the physical exam. He has no positive history of drug allergy. He won't smoke or uses any illicit drugs. The lab study is as bellow: Hgb: 8 g/dl WBC: 10000 /mm3 Plt: 300000 /ml MCV: 106 fL Hemoglobine electrophoresis: 91% HbS 6%HbF 3%HbA2 AST: 22 U/L ALT: 43 U/L Alk P: 53 U/L Ferritin: 1200 ng/ml

Clinical trial eligibility criteria: eligible ages (years): 15.0-40.0,  Sickle Cell Disease Disease severity: Participants with SCD who have 1 or more of the following (i-v) Clinically significant neurologic event (stroke) or any neurological deficit lasting > 24 hours History of two or more episodes of acute chest syndrome (ACS) in the 2-year period preceding enrollment despite the institution of supportive care measures (i.e. asthma therapy and/or hydroxyurea) History of three or more severe pain crises per year in the 2-year period preceding enrollment despite the institution of supportive care measures (i.e. a pain management plan and/or treatment with hydroxyurea) Administration of regular red blood cell (RBC) transfusion therapy, defined as receiving 8 or more transfusions per year for ≥ 1 year to prevent vaso-occlusive clinical complications (i.e. pain, stroke, and ACS). Patients on chronic transfusion who have to discontinue transfusion because of allo-sensitization will be eligible An echocardiographic finding of tricuspid valve regurgitant jet (TRJ) velocity ≥ 2.7 m/sec. Patients under the age of 18 years must have cardiac catheterization proven pulmonary arterial hypertension to qualify on this criterion. 2. Age: Patients must be 15 years of age inclusive OR if younger than 15 years must be pubertal 3. Adequate physical function as measured by Karnofsky/Lansky performance score ≥ 60 Cardiac function: Left ventricular ejection fraction (LVEF) > 40% or LV shortening fraction > 26% by cardiac echocardiogram or by MUGA scan Pulmonary function: Pulse oximetry with a baseline O2 saturation of ≥ 85% and DLCO > 40% (corrected for hemoglobin)  Availability of HLA matched sibling or 8 of 8 HLA-A, B, C and DRB1 matched unrelated donor Presence of donor specific antibodies in the patient Histological examination of the liver must document the absence of cirrhosis, bridging fibrosis and active hepatitis. The absence of bridging fibrosis will be determined using the histological grading and staging scale as described by Ishak and colleagues (1995). The presence of bridging fibrosis will be an criterion Uncontrolled bacterial, viral or fungal infection in the 6 weeks before enrollment Seropositivity for HIV Previous hematopoietic cell transplantation (HCT) Participation in a clinical trial in which the patient received an investigational drug or device or off-label use of a drug or device within 3 months of enrollment Demonstrated lack of compliance with prior medical care Unwilling to use approved contraception for at least 6 months after transplant A history of substance abuse in the last 5 years that interferes with care