Newly diagnosed severe aplastic anemia (SAA): patients <50 years of age (including pediatric patients) with SAA or very severe disease with HLA compatible sibling donors; pediatric SAA and vSAA patients with ≥9/10 compatible non-blood donors, HSCT may also be a first-line option; experienced transplant centers may try other alternative with fully informed patients and families Donor transplantation. Relapsed, refractory SAA: 1. SAA or vSAA that has failed or relapsed with immunosuppressive therapy (IST) and is <50 years old, with a non-blood donor or haploidentical donor with indications for transplantation, can also be attempted with cord blood transplantation at an experienced unit. 2. Failure or relapse of treatment by IST, age 50-60 years, fitness score ≤2, with SAA or vSAA, with a sibling compatible donor or non-hematologous donor can also be transplanted. 3, transfusion-dependent non-SAA patients, transplant timing and indications are the same as SAA.