Inclusion Criteria:
1. Voluntarily sign the informed consent form.
2. Aged between 18 and 65 years (inclusive), regardless of gender.
3. Diagnosed with systemic sclerosis (SSc) based on the 2013 American College of Rheumatology (ACR)/European League Against Rheumatism (EULAR) criteria for SSc.
4. Screened as diffuse cutaneous SSc patients with a disease duration of ≤5 years (disease onset defined as the time of the initial diagnosis of SSc).
5. Previously treated with at least two of the following therapies: corticosteroids, immunosuppressants, biologic agents, and others, and have a skin score of 10≤mRSS≤30 points.
Exclusion Criteria:
1. At screening, subjects with a forced vital capacity (FVC) predicted percentage \<50%.
2. Previously diagnosed with pulmonary arterial hypertension or, at rest, had a mean pulmonary arterial pressure \>25mmHg measured by right heart catheterization or had a systolic pulmonary artery pressure \>45mmHg measured by echocardiography at screening.
3. Presence of clinical symptoms requiring hospitalization for one of the following conditions at screening, whether newly occurring or worsening of pre-existing symptoms within 6 months: myocardial infarction, stroke, renal crisis, severe uncontrolled hypertension (≥160/100mmHg); or within 3 months: unstable ischemic heart disease, uncontrolled arrhythmia, heart failure (New York Heart Association III/IV stage), left ventricular ejection fraction \<50% as indicated by echocardiography, renal insufficiency, or hypertensive crisis as judged by the investigator.
4. Concurrent autoimmune connective tissue diseases other than systemic sclerosis, with the exception of patients with secondary Sjögren's syndrome.
5. Presence of any of the following laboratory abnormalities at screening:
1. Hematology abnormalities: Hemoglobin \<100g/L; White blood cell count \<3.0×109/L; Neutrophil absolute count \<1.5×109/L; Platelet count \<100×109/L.
2. Hepatic function abnormalities: ALT or AST \>3 times the upper limit of normal (ULN); Total bilirubin \>3 times ULN.
3. Renal function abnormalities: Estimated glomerular filtration rate (eGFR) \<60mL/min/1.73m2 or any clinically significant laboratory abnormalities that may affect the interpretation of study data or the subject's participation in the study as determined by the investigator.
6. Positive testing for human immunodeficiency virus (HIV) antibody, active syphilis, active hepatitis C (positive HCV antibodies and positive HCV-RNA), HBsAg positive and HBV-DNA positive at screening; history of severe active bacterial, viral, fungal, parasitic, or other infections during the screening period.
7. Receipt of live vaccines/attenuated vaccines within 2 months prior to enrollment.
8. Occurrence of any of the following within 3 months prior to enrollment: a. Major trauma or major surgery (including joint surgery) or anticipated major surgery during the study, which the investigator believes would pose an unacceptable risk to the subject. b. Plasma exchange or extracorporeal photopheresis treatment. c. Participation in any other clinical trials.
9. Prior treatment with stem cell-related drugs.
10. History of any malignancy within the past 5 years prior to enrollment, except for adequately treated or excised basal cell carcinoma, squamous cell carcinoma of the skin, or in situ cervical carcinoma.
11. Intolerance or contraindication to the study treatment, including any of the following: a. Allergy to albumin contained in the investigational product excipient. b. Lack of suitable peripheral venous access.
12. History of smoking, alcohol abuse, or drug abuse within the past 12 months or during the screening period:
1. Smoking defined as an average daily consumption of ≥5 cigarettes within the 3 months prior to screening.
2. Alcohol abuse defined as consuming more than 14 units of alcohol per week (1 unit of alcohol = 350ml of beer, or 45ml of spirits, or 150ml of wine) within the 3 months prior to screening.
3. Drug abuse defined as having a history of drug abuse.
13. Plans for conception during the trial period until at least 1 year after cell infusion, unwillingness to use effective contraceptive measures with their partners, or plans for sperm or egg donation.
14. Deemed unsuitable for participation in the study by the investigator.
