Phase II Clinical Trial of UC-MSCs in the Treatment of Knee Osteoarthritis

Inclusion Criteria: 1. Prior to conducting any assessment, written informed consent must be obtained; 2. Able to communicate well with researchers during screening, understand and comply with experimental requirements; 3. Age range from 40 to 70 years old (including threshold), regardless of gender; 4. Male weight ≥ 50 kg, female weight ≥ 45 kg, body mass index (BMI) within the range of 18-28 kg/m2 (including critical values); 5. According to the diagnostic criteria for knee osteoarthritis in the "Guidelines for the Diagnosis and Treatment of Osteoarthritis (2018 Edition)", subjects diagnosed with knee osteoarthritis (see Annex 1 for details); The course of knee osteoarthritis is more than 4 weeks; Other: 15\) There are contraindications to MRI examination or unwillingness to undergo MRI examination; 16) Hepatitis B, hepatitis C, AIDS, syphilis serological test positive pathogens; 17) Pregnant or lactating women, or male or female patients who tested positive for blood pregnancy during screening or have planned childbirth within 3 months after medication; 18) Patients who have received live vaccines or attenuated live vaccines within one month before administration; 19) Patients who have participated in clinical trials of other drugs or devices within 3 months prior to administration; 20) Patients with poor compliance, poor communication skills, inability to adhere to follow-up, and inability to complete the entire trial; 21) The researchers believe that it is not suitable for participants to enter this experiment. 6\) The target knee joint X-ray Kellgren Lawrence radiological grading (K-L IV grade) is II-III grade. Patients diagnosed with knee osteoarthritis on both sides should have non target knee joint symptoms, signs, and grading that do not exceed the target knee joint; 7) MRI examination shows partial or full layer damage to the cartilage of the knee joint; 8) A VAS score of ≥ 4 and ≤ 7 for knee joint pain at least 48 hours after discontinuing the use of all painkillers during screening; 9) Patients who use analgesic therapy (taking paracetamol/acetaminophen) to control local pain in the target knee joint agree to discontinue the use of similar analgesics 2 weeks prior to administration, and only allow NSAID as a rescue drug; Patients who use glucosamine, chondroitin, opioid drugs, or diacetate, glucosamine, etc. must agree to discontinue such drugs from 2 weeks prior to administration. \- Exclusion Criteria: * History of local/systemic treatment: 1. Individuals with a history of knee joint infection, surgery, and radiation therapy within 6 months prior to administration; 2. Combined instability of the knee joint (anterior and posterior cruciate ligaments, medial and lateral collateral ligaments), rupture, relaxation, or external deformity of the knee joint; 3. According to researchers, diseases that may interfere with knee joint function assessment, such as symptomatic lower back pain, lumbar disc herniation, and hip joint pain in the target knee joint; 4. According to the judgment of researchers, local diseases that may confuse knee joint function assessment include but are not limited to septic arthritis, reactive arthritis, clinically recurrent pseudogout, chondrocalcinosis, or joint fractures; 5. Within 3 months prior to administration, any medication injection treatment (including intra-articular injection of growth factors, hormones, or sodium hyaluronate) or lavage surgery has been received in the knee joint (target side) cavity; 6. Merge intra-articular or periarticular tumors (such as knee synovial chondroma, pigmented nodular synovitis, etc.); Systemic diseases and treatment history: 7. Various serious systemic diseases such as neurological disorders, respiratory disorders, heart diseases (NYHA grade III and above), and liver dysfunction (ALT\>3)×ULN or AST\>3×ULN, renal dysfunction Cr\>2×ULN or BUN\>2×ULN, coagulation dysfunction (INR\>1.5), or severe hematological disorders (such as grade 3 or above anemia, hemoglobin (Hb)\<8 g/dL, grade 2 or above thrombocytopenia, PLT\<75×10 \^ 9/L); 8. Diagnosed as systemic inflammatory arthritis or connective tissue disease, including but not limited to rheumatoid arthritis, psoriatic arthritis, ankylosing spondylitis, gout, Paget's disease, systemic lupus erythematosus, or other systemic diseases that may confuse KOA assessment (such as fibromyalgia); 9. Subjects who receive long-term (\>14 days) oral corticosteroids\>5 mg/day within 3 months prior to administration, or who require long-term glucocorticoid treatment during the trial period; 10. Previously received stem cell therapy; 11. Uncontrolled hypertension is defined as systolic blood pressure (SBP)\>160 mmHg or diastolic blood pressure (DBP)\>100 mmHg during screening; 12. Having a history of tumors, mental illness, severe autoimmune diseases, hematological diseases, and long-term use of immunosuppressants; 13. Have a history of alcohol and prohibited drug abuse; 14. Has a history of hypersensitivity to protein drugs;