The purpose of this study is to evaluate the safety and efficacy of human umbilical cord mesenchymal stem cell(hUC-MSC) for articular cartilage defect of knee.

Human articular cartilage has limited repair potential.Cell-based strategies have explored chondrocytes and mesenchymal stem cells (MSCs) with extensive basic science and preclinical studies.However the concept of autologous chondrocyte implantation is not ideal,so the focus in cartilage repair is shifting toward mesenchymal stem cells.

To investigate the effects of hUC-MSC treatment for articular cartilage defects, 20 patients will be enrolled and receive 4 times of hUC-MSC transplantation.

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