Inclusion Criteria:  Subjects who have been treated with placebo in phase 1/2a clinical trial of NEUROSTEM® Subjects who voluntarily decided to participate and signed the consent form after receiving explanations on the clinical trial (in case it is difficult for the participant to sign, the consent of the legal representative)  Exclusion Criteria:  History of stroke within 3 months prior to study enrollment Severe liver disorder (equivalent to double the normal values of ALT and AST) at Visit 1 Severe kidney disorder (serum creatinine ≥1.5mg/dL) at Visit 1  Abnormal Laboratory findings at Visit 1  Hemoglobin < 9.5 g/dL for male and <9.0 g/dL for female Total WBC Count < 3000/mm3 Total Bilirubin >= 3 mg/dL Suspected active lung disease based on chest X-ray at Visit 1 Bleeding disorder (abnormal blood coagulation test result (i.e. platelet count of < 137,000/mm3, PT ≥ 1.5 INR, or aPTT ≥ 1.5 x control anti-coagulant or anti-platelet, without anticoagulant or anti-platelet therapy) Diagnosis of cancer (of any body system, including brain tumor) Contraindicated for any of the tests performed during the clinical trial period (for example, MRI, CT, PET) Whom the principal investigator considers inappropriate for participation in the study due to any reasons other than those listed above