Human Umbilical Cord Mesenchymal Stem Cell Transplantation in Articular Cartilage Defect

Inclusion Criteria: * Patients must consent in writing to participate in the study by signing and dating an informed consent document * Healthy patients with no major history of illness * Patients must have a diagnosis of osteoarthritis by radiographic criteria of Kellgren and Lawrence grade 2-4 * Patients who needs invasive interventions of arthroplasty due to no response from existing pain medication * Patients must have had more than Grade 4 (0\~10 point numeric scale) pain at least for four months * Patient's damaged cartilage area should be in the range of 2-6cm2 Exclusion Criteria: * Pregnant women or lactating mothers * Patients who have received any anti-inflammatory drugs including herb-drug within 14 days * Patients who received any drug by intra-articular injection for treatment within 2 months prior to this enrollment * Patients with positive human immunodeficiency (HIV) at screening indicative of current of pass infection * Impaired liver function, abnormal blood coagulation, combine other tumor or special condition * Patients who had participated in other clinical trials within three months prior to this study