Umbilical cord blood mononuclear cells contain hematopoietic stem cells (HSC), mesenchymal stem cells (MSC), endothelial progenitor cells and other pluripotent stem cells, as well as immature immune cells, which can differentiate into chondrocytes, hematopoietic, epithelial, endothelial and nerve cells. It gives the ability to promote wound healing and vascular microcirculation reconstruction, and has the potential to treat many diseasesHowever, clinical studies on cord blood mononuclear cells in knee osteoarthritis have not been reported in the literature. Therefore, this study aims to explore the safety and effectiveness of cord blood mononuclear cells in the treatment of patients with knee osteoarthritis.

Inclusion Criteria:

• Age ≥30 years old, ≤75 years old, no gender limit;
• Meet the KOA diagnostic criteria in the "Classification Criteria for Knee Osteoarthritis" revised by the American College of Rheumatology (ACR);
• According to the X-ray K-L grading and evaluation standard, it is at level II-III;
• Continuous pain for at least 6 months;
• No local or systemic infection;
• There is no obvious contraindication for articular cavity puncture in hematology and biochemical testing;
• Subjects and their families understand the clinical trial protocol and agree to participate in the trial, voluntarily and sign an informed consent form;

Exclusion Criteria:

• Age<30 years old;
• Tumor diseases;
• Severe kidney, lung or liver damage;
• Blood diseases include anemia and thrombocytopenia;
• Type I diabetes;
• Severe effusion;
• Contracture or instability of the knee joint, with an axial deformity greater than 10°;
• Infectious arthritis or skin disease;
• Inject corticosteroids and immunosuppressants into the knee joint within 2 months;
• Suffer from mental illness and poor compliance;
• Cases that the investigator thinks are not suitable for inclusion in the group.