The primary objective: To evaluate the efficacy of intravenous infusion of universal UC-MSCs and CD83+MSCs subpopulation injection in the treatment of sepsis by using the 28-day survival rate of the subjects as the primary efficacy criterion.The secondary objectives: 1. To systematically evaluate the safety of universal UC-MSCs and CD83+MSCs subpopulation in the treatment of sepsis; 2. To provide theoretical basis and clinical research data for establishing a safe, effective and feasible clinical treatment plan for sepsis using stem cells.

Inclusion Criteria:

• Age: 0-65 years old, diagnosed with sepsis
• Clinical diagnosis of sepsis (based on Sepsis 3.0 International Guidelines)
• Confirmed or suspected infection

Exclusion Criteria:

• Violation of medical ethics

• Significant confounding factors likely to bias study outcomes

• Poor adherence to the study protocol

• Concurrent participation in other clinical trials

• Specific medical conditions:

  1. History of chronic enteritis, neuropsychiatric disorders, or transplantation (bone marrow, lung, liver, pancreas, or small intestine)
  2. Severe primary diseases affecting survival (e.g., life-limiting hepatic, renal, or endocrine disorders) or psychiatric disorders
  3. History of hypersensitivity or severe adverse reactions to biological products
  4. Imminent terminal status (e.g., septic shock, life expectancy <7 days)
  5. Foreseeable risk of medical errors or disputes during hospitalization
  6. Active drug-resistant infections
  7. History of malignancy at screening
  8. Pregnancy, lactation, or plans for pregnancy within the next year