The aim of the study is to compare the clinical effects of treatment of knee osteoarthritis using adipose tissue mesenchymal stromal cells obtained by an enzymatic method with the outcomes of the therapy with the mechanically fragmented adipose tissue. Identification and functional analysis of the regenerative capacity of MSCs derived from the adipose tissue depending on three variables (body weight, sex and age) will help to develop a targeted therapy for different groups of patients and will determine the effectiveness of both methods of treatment. An attempt was made to identify the groups of patients with the greatest regeneration potential of the adipose tissue, and thus indicate those with the most probable improvement of the joint condition.

Based on the calculation of the sample size using power analysis of the test, investigators plan to include 100 adults with primary knee osteoarthritis in this study. The patients will undergo lipoaspiration under sterile conditions of the operating theatre, the collected lipoaspirates will be further processed - enzymatically with the use of collagenase or mechanically using the Lipogems system. After collection, lipoaspirates will be immediately transferred to the laboratory of the Department of Regenerative Medicine with a tissue and cells bank in Warsaw, and the preparations will be administered to the patients' knee joints in the operating room under ultrasound control.

The Lipogems system is defined as a minimal tissue manipulation system. In contrast, the administration of preparations produced using an enzymatic method requires advanced actions.

Lipoaspiration will be performed using blind cannulas and vacuum syringes introduced through the abdominal wall with a three-millimetre incision on the skin after previous injection to the adipose tissue with modified Klein's solution (500 ml of saline solution, 1 ml of adrenaline, 40 ml of 2% lignocaine), which makes the collection easier. 10 ml of the collected adipose tissue will be used to examine the samples after previous gradient drainage from Klein's solution. Immediately after collection, the samples will be sent to the laboratory for analysis (cell count testing, culture, phenotype identification, analysis by flow cytometry).

The patients will be monitored in the hospital outpatient clinic for one year after the procedure; the control visits will take place: after 2 and 6 weeks, then after 3 and 6 months and after a year. A physical examination and the assessment using the KOOS questionnaire will be performed. Before the procedure and after one year, an X-ray and MRI with T-2 Mapping will be carried out in order to evaluate the condition of the cartilage.

Inclusion Criteria:

• Adults with symptomatic gonarthrosis diagnosed based on the X-ray, MRI and clinical examination, previously unsuccessfully treated (rehabilitation, NSAIDs, hyaluronic acid, platelet-rich plasma)
• Primary knee osteoarthritis
• Willingness and consent to participate in the study
• Readiness to attend control visits

Exclusion Criteria:

• Failure to meet the inclusion criteria
• Active chronic infection
• Metal implant made of a ferromagnetic material that will exclude the patient from magnetic resonance imaging
• Use of anticoagulants
• General and intra-articular use of steroids during the last year
• Pregnancy, breastfeeding
• Any autoimmune and rheumatic disease, or conditions that influence the accuracy of test results
• Taking drugs or cytostatic medications in the last 30 days
• Mental disorders, alcohol and drug addiction