To define the clinical effects of intra-articular transplantation of bone-marrow-derived (BM-MMSCs) and placenta-derived multipotent mesenchymal stem / stromal cells (P-MMSCs) for knee osteoarthritis.

Multipotent mesenchymal stem / stromal cells (MMSCs) of different origin are the novel therapeutic agents that can slow down cartilage degeneration, improve reparation and ultimately prevent joint prosthetics. MSCs are capable to direct differentiation into chondrocytes, produce cytokines and growth factors with immunomodulatory and anti-inflammatory effects, stimulate angiogenesis, as well as induce chemotaxis of endogenous progenitors. Bone marrow-derived and placenta-derived MMSCs can be considered the most promising source for cell therapy of joints disorders according to availability, safety and expected therapeutic efficacy.

Inclusion Criteria:

1. Clinical diagnosis of knee osteoarthritis.
2. Age: 18 to 75 years old.
3. Kellgren-Lawrence Grade 2 or 3 according to X-ray imaging.
4. Knee pain.
5. Written informed consent

Exclusion Criteria:

1. Age <18 or >75 years of age by time of infusion.
2. Participation in an on-going investigational therapeutic or device trial 30 days of consent.
3. Rheumatoid arthritis.
4. Psoriatic arthritis.
5. Juvenile idiopathic arthritis.
6. Gout.
7. Infectious arthritis.
8. Osteomyelitis.
9. Osteonecrosis.
10. Inflammatory arthritis.
11. Chondropathy.
12. Joint contracture.
13. Arthroplasty.
14. Arthroscopy within 6 months prior to study entry.
15. Intra-articular injection within 3 months prior to study entry.
16. Hormone intake.
17. Antiaggregants and anticoagulants intake.
18. Immunosuppressants intake.
19. Allergy to hyaluronic acid.
20. History of organ or cell transplantation.
21. Hematologic abnormality evidenced by hematocrit < 25%, white blood cell < 2,500/ul or platelet count < 100,000/ul.
22. Active infection.
23. Positive for HIV antigen.
24. History of hepatitis B, hepatitis C.
25. History of malignancy in the last 5 years prior to study entry.
26. Active tumors.
27. History of myocardial infarction.
28. History of stroke.
29. Renal failure with chronic hemodialysis.
30. Liver Cirrhosis (ICGR 15 >30%).
31. Chromosomal abnormality.
32. Peripheral nervous system disorders.
33. Cognitive or language barriers that prohibit obtaining informed consent or any study elements.
34. History of drug abuse or alcohol abuse, or documented medical, occupational, or legal problems arising from the use of alcohol or drugs within the past 24 months.
35. Pregnant/nursing women or women of child-bearing potential.
36. Other condition that limits lifespan to < 1 year.