Inclusion Criteria:
* Severe aplastic anemia;
* Aged 40-60 years old;
* Weight 45Kg-100Kg;
* Eastern Cooperative Oncology Group (ECOG) score ≤3;
* No major organ injury (ECG ejection fraction \>45%; bilirubin \< 2 times the upper limit of normal value; AST and ALT \< 3 times the upper limit of normal value; serum creatinine \< 2 times the upper limit of normal value);
* No severe infection;
* Subjects voluntarily participated in this clinical trial and signed the informed consent.
Exclusion Criteria:
* With other hematologic diseases;
* Expected survival of less than 1 month;
* Previous autologous or allogeneic hematopoietic stem cell transplantation;
* Pregnant patients;
* Patients with severe mental or neurological disorders that would affect the ability to provide informed consent and/or to report or observe adverse events;
* Other conditions that the investigator determines to be inappropriate for enrollment.
* Current or recent (\<4 weeks prior to screening) clinically serious viral, bacterial, fungal, or parasitic infection
* A history of symptomatic herpes zoster infection within 12 weeks prior to screening
* Active or chronic viral infection from hepatitis B virus (HBV), hepatitis C virus (HCV), or human immunodeficiency virus (HIV)
* Have evidence of active tuberculosis (TB), or have previously had evidence of active TB and did not receive appropriate and documented treatment, or have had household contact with a person with active TB and did not receive appropriate and documented prophylaxis for TB
* Exposure to a live vaccine within 12 weeks prior to enrollment or expected to receive a live vaccine during the study
* Clinically significant thrombotic event within 24 weeks of screening or are on anticoagulants and in the opinion of the investigator are not well controlled
* Myocardial infarction (MI), unstable ischemic heart disease, stroke, or New York Heart Association Stage IV heart failure
* A history or presence of cardiovascular, respiratory, hepatic, gastrointestinal, endocrine, neurological, or neuropsychiatric disorders or any other serious and/or unstable illness that, in the opinion of the investigator, could constitute an unacceptable risk when taking investigational product or interfere with the interpretation of data
* Any of the following specific abnormalities on screening laboratory tests:
1. ALT or AST \>2 x ULN, or total bilirubin ≥1.5 x ULN
2. hemoglobin \<9 g/dL, or total white blood cell (WBC) count \<2,500/µL, or neutropenia (absolute neutrophil count \<1,200/µL), or lymphopenia (lymphocyte count \<750/µL)
3. eGFR \<50 mL/min/1.73 m2
