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 no morphologic evidence of clonal evolution (patients with isolated bone marrow cytogenetic abnormalities are also eligible). 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 attenuated vaccine within 2 months before transplantation 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 With contraindications to treatments used during the research 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