The proposed study will assess primary safety and secondary efficacy endpoints of allogeneic UC-MSC-derived MTF administered to two arms osteoarthritis patients with grade 2, 3, or 4 radiographic OA severity (20 per arm). The first arm will receive an intra-articular injection of MTF into the knee joint under fluoroscopy. The second arm will receive 12 subcutaneous MTF injections, once per week.