Safety and Efficiency of Umbilical Cord-derived Mesenchymal Stem Cells(UC-MSC) in Patients With Alzheimer's Disease

Inclusion Criteria: * Men and women who are age in the range of 50 to 85 * All women: go into menopause * Probable Alzheimer's disease as determined by NINCDS-ADRDA criteria * MMSE score between 3 and 20, both inclusive * Voluntarily participating subject who sign the consent form Exclusion Criteria: * Subject with cancer * Subject with positive test for Human Immunodeficiency Virus(HIV) * Subject who cannot undergo Magnetic Resonance Imaging(MRI), computed tomography(CT) screening * Subject with psychological diseases (i.e. depression, schizophrenia, bipolar disorder, etc) * Subject with dementia caused by other than Alzheimer's disease (i.e. infection of central nervous system, Creutzfeld-Jacob disease, severe head trauma, Pick's disease, Huntington's disease, and Parkinson's disease) * Subject with vascular dementia as determined by the clinical criteria of Design Standards Manual(DSM) IV and the imaging criteria of Erkinjuntii * Subject with severe white matter hyperintensities (WMH); Severe WMH is defined that length of the deep white matter is 25 mm or longer and length of the periventricular capping/banding is 10 mm or longer. * Subject who have had stroke in 3 months. * Subject with severe kidney failure (1.5 mg/dL of serum creatinine or more) Hemoglobin \< 9.5 g/dL for men, \< 9.0 g/dL for women; Total WBC count \< 3000/mm3; Total bilirubin ≥ 3 mg/dL * Subject who is suspect to have active lung diseases based on check X-ray result * Subject who have been excluded in the subject selection process for this study before * A platelet count \< 150,000/mm3; Plasma prothrombin time(PT)≥ 1.5; the international normalized ratio (INR) or activated partial thromboplastin time(aPTT)≥ 1.5X control value * Subject who is determined inappropriate by the investigators