1. To assess the safety of allogeneic injection of expanded ADSCs to patients with knee osteoarthritis
2. To assess the efficacy of allogeneic injection of expanded ADSCs to patients with knee osteoarthritis

Inclusion Criteria:

1. Aged 40-80 years (inclusive)
2. Kellgren-Lawrence grading I-III, as determined by American College of Rheumatology (ACR) criteria for osteoarthritis of the knee
3. Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) pain score of 7-17 in the study knee even if treated with chronic doses of non steroidal anti-inflammatory drugs
4. Having provided informed consent

Exclusion Criteria:

1. With previous surgery of articular fracture, ligament reconstruction, meniscal reconstruction, and knee arthroplasty on the target knee joint
2. With previous intra-articular intervention on the target knee joint within past 3 months (e.g. steroid, anaesthetic, sodium hyaluronate)
3. Known or suspected infection of the target knee joint
4. Ascertained hypersensitivity to any component used in the study
5. Administered with systemic anti-inflammatory drugs (e.g. non-steroidal anti-inflammatory drug or steroid ) or topical anti-inflammatory drugs on target knee within 7 days prior to administration in the study
6. With serious prior or ongoing medical conditions (e.g. concomitant illness such as cardiovascular (e.g. New York Heart Association grade III or IV), hepatic (e.g. Child-Pugh Class C), psychiatric condition, alcoholism, drug abuse), medical history, physical findings, , or laboratory abnormality that in the investigators' opinion could interfere with the results of the trial or adversely affect the safety of the patient
7. With any evidence of malignant disease with life expectancy of less than 1 year
8. Pregnant or lactating women or planning to be pregnant during the study period
9. With body mass index (BMI) greater or equal to 35 kg/m2
10. With joint diseases except knee osteoarthritis considered by investigator not eligible to enter the study
11. With known history of human immunodeficiency virus (HIV) infection.
12. Judged to be not applicable to this study by investigator such as difficulty of follow-up observation
13. With any other serious diseases/medical history considered by the investigator not in the condition to enter the trial
14. Having participated other investigational study within 4 weeks of entering this study
15. With known history of claustrophobia
16. Having any existing active/inactive implanted medical devices, such as cardiac pacemaker, cochlear, intracranial vascular clips or neurostimulator, etc...
17. Having any existing metallic intraocular foreign body