This study will investigate the safety and efficacy of allogeneic umbilical cord-derived stem cell therapy in treating patients with moderate to severe systemic lupus erythematosus.

Inclusion criteria:

1. Fully understand the purpose, nature, methods of the trial, as well as possible adverse reactions, voluntarily participate as a subject, and sign the informed consent form.
2. Age 18-65 years old (inclusive of the boundaries, based on the date of signing the informed consent form), regardless of gender;
3. The subjects (both male and female) must agree not to have a reproductive plan during the trial period and after the injection administration for at least 12 months, and voluntarily take effective contraceptive measures with their partners (see Appendix 1), and have no plans for sperm donation or egg donation;
4. According to the diagnostic classification criteria of the European League Against Rheumatism (EULAR) and the American College of Rheumatology (ACR) in 2019, diagnosed with systemic lupus erythematosus (SLE);

Inclusion Criteria:

1. Fully understand the purpose, nature, methods of the trial and possible adverse reactions, voluntarily become a subject, and sign the informed consent form.
2. Age 18-65 years old (inclusive of the boundary values, based on the time of signing the informed consent form), no gender restrictions;
3. The subjects (male and female) must agree not to have a reproductive plan during the trial period and after the injection administration for at least 12 months, and voluntarily take effective contraceptive measures with their partners (see Appendix 1), and have no plans for sperm donation or egg donation;
4. According to the diagnostic classification criteria of the European League Against Rheumatism (EULAR)/American College of Rheumatology (ACR) in 2019, diagnosed with systemic lupus erythematosus (SLE);
5. Meet one of the following conditions: the antinuclear antibody (ANA) is positive at 1:80 during screening or the anti-dsDNA antibody is positive during screening or the anti-Sm antibody is positive during screening;

Exclusion Criteria:

1. Those who are judged by the researchers to be likely to be allergic to the investigational drug or any component thereof;
2. Those who have had central nervous system diseases within 8 weeks before administration (including but not limited to epilepsy, mental illness, interstitial encephalopathy syndrome, stroke, encephalitis, central nervous system vasculitis, etc.);
3. Those who have undergone major organ transplantation (such as heart, lung, kidney, liver) or hematopoietic stem cell/marrow transplantation;
4. Those who have any major diseases/diseases or unstable clinical conditions (such as liver, kidney, hematological, endocrine, pulmonary, immune, mental, etc.) or active infections/infectious diseases with evidence, and according to the researchers' clinical judgment, if the subjects participate in the study, it will significantly increase the risks for the subjects;
5. Those who currently have known or suspected malignant tumors;
6. Those who have severe pulmonary arterial hypertension (>70 mmHg, 1 mmHg = 0.133 kPa), or mild to moderate pulmonary arterial hypertension patients with severe cardiopulmonary insufficiency;
7. Those who have antiphospholipid syndrome (APS), or have a history of catastrophic antiphospholipid syndrome (CAPS), or although not diagnosed as APS, but are evaluated by the researchers as having an increased risk of thrombosis;
8. Those who have herpes zoster infection within 90 days before administration, or any infection that requires hospitalization treatment or intravenous or intramuscular injection of antibiotics within 60 days before administration;
9. Those who have undergone major surgical operations within 28 days before administration, or those who are expected to undergo major surgical operations during the trial;
10. Subjects who have positive serological tests for viral hepatitis during the screening period, positive human immunodeficiency virus antibody (HIV-Ab), positive hepatitis B surface antigen (HBsAg), positive hepatitis C antibody (HCV-Ab), or positive Treponema pallidum antibody (TP-Ab);
11. Other situations that the researchers consider may affect the subjects' willingness to provide informed consent or follow the trial protocol, or situations where the subjects' participation in the trial may affect the trial results or their own safety.