This is a phase 2b randomized, double-blind, Placebo-controlled study with 2 treatment arms, to compare the efficacy and safety of AstroStem vs. Placebo treatment in patients with mild Alzheimer's Disease(AD). Eligible patients diagnosed with AD within one year of the start of treatment will be enrolled. Patients who are randomized into the treatment group will be administered via intravenously AstroStem every 4 weeks from Week 0 to Week 36. On the other hand, patients who are randomized into the placebo control group will receive Placebo every 4 weeks from Week 0 to Week 36. After the final administration, patients will be scheduled for two follow-up visits, at Weeks 44 and 52, to assess efficacy and safety endpoints.

Inclusion Criteria:

• Male or female patients aged 50 and above at the time of signing the Informed Consent Form
• Patients who can understand and provide written informed consent (assent)
• Patients who have a diagnosis of probable mild Alzheimer's Disease(AD) according to the National Institute of Neurological and Communicative Disorders and Stroke; Alzheimer's Disease and Related Disorders Association (NINCDS-ADRDA) criteria within one year of the start of treatment
• Patients who have an MMSE Score of 20 to 24 at screening
• Patients who have a Clinical Dementia Rating (CDR)-Global Score of 0.5 to 1 at baseline
• Patients who have any FDA-approved AD medication (donepezil, galantamine, memantine, rivastigmine or any combination) since their AD diagnosis receiving a stable dose of medical teratment for at least 12 weeks prior to Screening and were to stay on a stable dose during the study
• Patients who have one (or more) identified adult caregiver (study partner) who is able to read, understand, and speak the designated language at the study site; who either lives with the subject or sees the subject for ≥2 hours/day ≥4 days/week; and who agrees to accompany the subject to each study visit and to participate in the subject's clinical assessments
• Patients who have a diagnosis of probable mild AD according to Amyloid PET scan at screening

Exclusion Criteria:

• Female patients who are pregnant, nursing, or of childbearing potential while not practicing effective contraception
• Patients who have signs of delirium
• Patients who have had a cortical stroke within the preceding 2 years
• Patients who have a prolonged QTc interval at screening; >450 msec for males or >470 msec for females
• Patients who have a diagnosis of severe white matter hyperintensity (WMH), which is defined as ≥25mm of the deep white matter and ≥10mm of the periventricular capping/banding in lengths
• Patients who have a diagnosis of dementia or cause of cognitive impairment other than AD
• Patients who have a significant abnormal result in laboratory tests, in the opinion of the investigator
• Patients who have participated in any investigational drug, stem cell therapy, or device trial within the previous 3 months at screening
• Patients with any current psychiatric diagnosis other than AD if, in the judgment of the investigator, the psychiatric disorder or symptom is likely to confound interpretation of drug effect, affect cognitive assessments, or affect the subject´s ability to complete the study
• Patients who are known to have autosomal dominant mutation-associated presenile AD
• Patients who show signs of Acquired Immunodeficiency Syndrome (AIDS), Hepatitis B Virus (HBV), Hepatitis C (HCV), Venereal Disease Research Laboratory (VDRL)
• Patients who have any conditions that would contraindicate an MRI, such as the presence metallic objects in the eyes, skin, or heart
• Patients who have >4 cerebral microhemorrhages (regardless of their anatomical location or diagnostic characterization as "possible" or "definite"), a single area of superficial siderosis, or evidence of a prior microhemorrhage as assessed by MRI
• Patients who have history of malignant cancer within the last 5 years (The following is a partial list of conditions that are permissible for study entry: non-metastatic basal and/or squamous cell carcinoma of the skin, in situ cervical, or non-progressive prostate cancer)
• Patients who have suspected active lung disease based on chest X-ray
• Patients who are hypersensitive to fetal bovine serum or penicillin
• Patients who are currently using immunosuppressants, cytotoxic drug, corticosteroids or similar steroidal anti-inflammatory medication (e.g., Prednisone) on a regular basis (exceptions allowed include; regular use of steroidal nasal sprays, topical steroids, and estrogen-replacement therapy)
• Patients for whom the investigator judges the liposuction may cause a problem