Haploidentical Allogeneic Hematopoietic Stem Cell Transplantation With Post-transplant Cyclophosphamide in Patients With Acquired Refractory Aplastic Anemia or in Relapse After Immunosuppression

Inclusion Criteria: * Aged from 3 to 35 years old * Suffering from refractory acquired idiopathic aplastic anemia (at least one course of immunosuppression with anti-thymocyte globulin) * Absence of geno-identical donor or 10/10 matched donor * With identification of a haploidentical donor (brother, sister, parents, adult children or cousin) * Absence of donor specific antibody detected in the patient with a MFI ≥ 1500 (antibodies directed towards the distinct haplotype between donor and recipient) * With usual criteria for HSCT : * ECOG(Eastern Cooperative Oncology Group) ≤ 2 * No severe and uncontrolled infection * Cardiac function compatible with high dose of cyclophosphamide * Adequate organ function: ASAT(aspartate transaminase) and ALAT (alanine aminotransferase) ≤ 2.5 N (the norm), total bilirubin ≤ 2N, creatinine \< 150 μmol/L * With health insurance coverage * Contraception methods must be prescribed during all the duration of the research. Women and men of childbearing age must use contraceptive methods within 12 months and 6 months after the last dose of cyclophosphamide, respectively. * Having signed a written informed consent (2 parents for patients aged less than 18) Exclusion Criteria : * With morphologic evidence of clonal evolution (patients with isolated bone marrow cytogenetic abnormalities are also eligible excepted chromosome 7 abnormalities and complex karyotype) * With uncontrolled infection * With seropositivity for HIV or HTLV-1 (Human T cell Leukemia) or active hepatitis B or C defined by a positive PCR (polymerase chain reaction) HBV (hepatitis B virus) or HCV (hepatitis C virus) and associated hepatic cytolysis * Cancer in the last 5 years (except basal cell carcinoma of the skin or "in situ" carcinoma of the cervix) * Pregnant (βHCG positive) or breast-feeding. * Who received live attenuated vaccine within 2 months before transplantation and during the research * Uncontrolled coronary insufficiency, recent myocardial infarction \<6 month, current manifestations of heart failure, uncontrolled cardiac rhythm disorders, ventricular ejection fraction \<50% * With heart failure according to NYHA (New York Heart Association) (II or more) * Preexisting acute hemorrhagic cystitis * Renal failure with creatinine clearance \<30ml / min * With urinary tract obstruction * Who receive the following treatments Phenytoin, Pentostatin, inhibitor of adenoside) * Who have any debilitating medical or psychiatric illness, which preclude understanding the inform consent as well as optimal treatment and follow-up * Under tutorship or curatorship