This study aimes to evaluate the clinical efficiency of autologous adipose tissue-derived MSC transplantation in patients with confirmed osteoarthritis at grade II and III. Adipose tissue is isolated from the belly, and used for extraction of the SVF. The SVF is mixed with activated platelet-rich plasma before injection. The clinical efficiencies are evaluated by the pain score (VAS), Lysholm score, and MRI findings. SVF is isolated from about 100 mL of adipose tissue, and PRP is prepared from 20 mL of peripheral blood. Total injection volume will be about 5-10 mL. The total number of SVF to be injected is 1.0 x 10(7) to 5 x 10(7).