To evaluate the clinical efficacy and safety of dental pulp mesenchymal stem cells in the treatment of primary mild to moderate knee osteoarthritis through a comparative study with sodium hyaluronate.

20 participants will receive low dose of dental pulp mesenchymal stem cells, 20 participants will receive high dose and another 20 participants will receive sodium hyaluronate

60 participants will receive to evaluate the clinical efficacy and safety of dental pulp mesenchymal stem cells in the treatment of primary mild to moderate knee osteoarthritis through a comparative study with sodium hyaluronate and verify the basis of dental pulp mesenchymal stem cells in the treatment of primary knee osteoarthritis, and to explore a more effective and safe clinical treatment of knee osteoarthritis.

Inclusion Criteria:

1. Complying with the diagnostic criteria for primary knee osteoarthritis revised by the American Rheumatological Association (1995), age 40-70 years, gender-free.
2. For patients with mild to moderate knee arthritis, the WOMAC score of knee joint was less than 120.
3. X-ray Kellgren-Lawrence was used to evaluate the grade I, II and III of osteoarthritis.
4. Fertility patients should take effective contraceptive measures until the end of follow-up. Fertility women should exclude the possibility of early pregnancy, that is, HCG negative test in early pregnancy.
5. Voluntary participation in this clinical study, can cooperate with doctors to carry out research, stop all medical measures for knee arthritis for more than 2 weeks, and sign the informed consent of patients.

Exclusion Criteria:

(1) Those with other diseases that may affect the knee joint, such as rheumatoid arthritis, ankylosing spondylitis, rheumatoid arthritis, gout and other rheumatic diseases, bone tumors, osteoporosis, bone tuberculosis or obvious history of acute trauma, resulting in meniscus injury, ligament rupture and vascular nerve injury; those with previous history of femur, tibial plateau, tibia and fibula fracture. The patients with gonarthritis, the patients with knee joint and surrounding skin infection were not cured.

2) Patients who have undergone surgery and other factors affecting the efficacy of the treatment. Patients with severe deformities or even deformities of the knee joint, who need surgical treatment. Patients who have received knee joint irrigation or arthroscopic examination within one year.

3) Patients with systemic cancer tendency or cancer and patients with systemic infection in active stage.

4) Patients with severe heart, lung, liver, kidney, blood system, endocrine system and immune deficiency, or abnormal laboratory biochemical indicators, namely: hemoglobin (Hb) < 9 g/dL, white blood cell (WBC) > 15 x 109/L, platelet (Pt) < 100 x 109/L, glutamic oxalate transaminase (AST) and alanine aminotransferase (ALT) > 1.5 times normal upper limit; serum creatinine > 1.5 times normal upper limit.

5) Physical history or clinical manifestations with bleeding tendency, including patients currently using anticoagulants.

6) Patients with uncontrollable epileptic seizures, psychosis or Alzheimer's disease who are unable to complete the scale.

7) Pregnant or lactating women, legal disabled patients (blind, deaf, dumb, mentally retarded, physically disabled), drug addiction and other adverse drug addiction.

8) Patients with contraindications or allergies were examined and treated in this study.

9) Those who have participated in other clinical studies within one month.

10) Researchers consider it inappropriate for patients to participate in this clinical study.