Safety and Efficacy of Allogenic Umbilical Cord Blood-derived Mesenchymal Stem Cell Product

Inclusion Criteria: * Non-responder to conservative treatment for radiographically confirmed (by MRI) osteochondral lesion of talus with ankle pain and/or stiffness and less than 75 of the AOFAS score * Age between 20 and 70 year-old * Appropriate function of blood clot PT(INR) \< 1.5, APTT \<1.5×control * Appropriate renal function Creatinine ≤ 2.0 ㎎/㎗, proteinuria less than trace with Dipstick urine test * Appropriate hepatic function Bilirubin ≤ 2.0 ㎎/㎗, AST/ALT ≤ 100 IU/L * No evidence of autoimmue disorder As screening test anti-nuclear antibody and/or anti-thyroglobulin antibody, if positive rheumatologist referral needed to confirm diagnosis * No surgery or radiotherapy for the same ankle joint within 6 weeks * Female patients agreeing with maintenance of contraception during study period * No ligament instability greater than grade II (Grade 0 : none, Grade Ⅰ: 0\~5㎜, GradeⅡ: 5\~10㎜, Grade Ⅲ: \>10㎜) with physical exam * Patients agreeing with participation in this study and signed on informed consent by their own will Exclusion Criteria: * Degenerative ankle arthritis patients * Patients with autoimmune disease * Patients with infectious disease needed parenteral antibiotics * Patients with myocardial infarction, congestive heart failure, other serious heart diseases or uncontrollable hypertion * Patients with other serious medical illness * Pregnancy or breast feeding patients * Past history related with psychiatric illness or epilepsy * Alcoholic abuse * Heavy smoker * Chronic inflammatory disease including rheumatoid arthritis * Participants of other clinical trial within 4 weeks * Patients treated with immunosuppressing agents such as Cyclosporin A or azathioprine within 6 weeks * Unstable ankle joint(lesion site) greater than grade II at physical exam (Grade 0 : none, grade Ⅰ: 0\~5㎜, GradeⅡ: 5\~10㎜, Grade Ⅲ: \>10㎜) * Other inappropriate patients determined by the prinicipal investigator