The primary objective of this study is to evaluate the safety and feasibility of intraarticular injection of Celution prepared adipose-derived regenerative cells injected into knees of patients with chronic knee pain due to osteoarthritis.

The ACT - OA Knee Clinical Trial is a prospective, randomized, multi-center device trial intended to assess safety and feasibility of intraarticular administration of Celution processed Adipose Derived Regenerative Cells (ADRCs). The study will include 90 patients in up to 15 sites in the United States.

Subjects that have chronic knee pain due to idiopathic osteoarthritis of the knee (confirmed clinically and radiologically) will be evaluated for eligibility in this study. Following informed consent and screening evaluations, eligible subjects will undergo pre-operative testing. Subjects will then undergo fat harvest through small volume liposuction under local anesthesia. Lipoaspirate will be processed in the Celution System to isolate and concentrate ADRCs for immediate intraarticular administration. A dose escalation approach has been designed wherein the study is divided into two double-blind, randomized, placebo-controlled parts as follows:

Part A:

Low Dose (20,000,000 cells): 30 patients OR Placebo: 15 patients

Part B:

High Dose (40,000,000 cells): 30 patients OR Placebo: 15 patients

Subjects randomized to placebo will undergo fat harvest and intraarticular injection of a placebo that has been visually matched to the active test substance. All subjects will undergo imaging studies, clinical evaluations, and laboratory testing prior to and after the procedure; patients will be followed for 48 weeks after intraarticular injections are performed.

Inclusion Criteria:

1. Males or females ≥ 40 and < 70 years of age
2. Able to provide written informed consent
3. Diagnosis of osteoarthritis in one or both knees by American College of Rheumatology (ACR) criteria
4. Kellgren and Lawrence grade 2 or 3 (standing AP x-ray) of the target knee within the preceding 6 months
5. Pain due to osteoarthritis in the target knee ≥ 6 months
6. Minimum score of "moderate" from KOOS question about pain on walking on a flat surface.
7. Minimum score of "moderate" from KOOS question about degree of difficulty during walking on a flat surface.
8. Continued knee pain and limitations in knee function despite prescription of conservative therapy for at least 6 months.
9. Ability to safely undergo liposuction that will result in the harvest of a sufficient quantity of adipose tissue (approximately 300 mL)
10. On stable regimen of one analgesic medication (rescue medication) for their knee pain due to osteoarthritis and ability and willingness to use the same analgesic medication during the study (screening period through to final study visit).
11. Ability to perform procedures required of the pain index evaluations (unassisted walking 50 feet on a flat surface and going up and down stairs)

Exclusion Criteria:

1. Any major injury to the target knee within the 12 months prior to the screening visit
2. Need for cane or other assistance device for walking
3. Any surgery to the target knee within the 6 months prior to the screening visit, or surgery to the contralateral knee or other weight-bearing joint if it will interfere with knee assessments
4. Prior articular transplant procedures
5. Prior ligament reconstruction to the target knee within 12 months prior to the screening visit
6. Inflammatory arthropathies such as rheumatoid arthritis, lupus arthropathy, or psoriatic arthritis
7. Gout or calcium pyrophosphate (pseudogout) diseases that have flared within the previous 6 months prior to the screening visit
8. X-ray findings of acute fractures, known severe loss of bone density (as determined by the investigator), avascular necrosis, and/or severe bone or joint deformity in the target knee (>5 degree valgus or varus deviation from mechanical axis)
9. Fibromyalgia, pes anserine bursitis, lumbar radiculopathy, and/or neurogenic or vascular claudication
10. Primary knee pain due to diagnosed isolated patella-femoral arthritis or chondromalacia in the target knee
11. Significant target knee joint infection or skin disorder/infection within the previous 6 months prior to the screening visit
12. Symptomatic OA of the hips, spine, or ankle, if it would interfere with the evaluation of the target knee
13. Any condition requiring immunosuppressive medication or use of systemic steroids
14. Intra-articular injection of steroids in previous 3 months or hyaluronic acid in previous 6 months in one or both knees prior to the screening visit
15. Patients that have received PRP, other platelet-based product, or investigational treatment in another cell/biologic study for the targeted treatment injury in the 12 months prior to the injection procedure
16. Participation in any experimental drug or device study within the 6 months prior to the screening visit
17. Obesity defined as BMI > 35 kg/m2