This is a Phase I, prospective, randomized, placebo-controlled, double-blinded study designed to test the safety and efficacy of LMSCs (Longeveron Mesenchymal Stem Cells) for the treatment of subjects with clinically diagnosed Alzheimer's disease.

This is a randomized, placebo-controlled clinical trial designed to evaluate the safety and efficacy of LMSCs (Longeveron Mesenchymal Stem Cells) or placebo in subjects with Alzheimer's Disease. Following a successful Safety Run-In Phase, a total of twenty-five (25) subjects will be randomized to (2:2:1) to receive low-dose LMSCs, high-dose LMSCs or placebo. After randomization, baseline imaging, and study product infusion, subjects will be followed up at 2,4,13, 26, 39 and 52 week post study product infusion. Intention-to-treat study population will be used for the purpose of the endpoint analysis and safety evaluations.

Inclusion Criteria: All subjects enrolled in this trial must:

• provide written informed consent;
• be 50 - 80 years of age at the time of signing the Informed Consent form;
• have a body mass of 45 - 150 kg;
• at the time of enrollment, be diagnosed with AD in accordance with the NINCDS-AA criteria;
• score between 18 and 24 on the Mini Mental State Examination (MMSE);
• has one (or more) identified adult caregiver who is willing to provide written informed consent for his/her own participation; is able to read, understand, and speak the designated language at the study site; either lives with the subject or sees the subject for ≥2 hours/day ≥3 days/week; and agrees to accompany the subject to each study visit;
• blood oxygen saturation ≥93% determined via pulse oximetry;
• have a brain MRI consistent with AD;
• have a PET scan using an FDA-approved tracer (e.g., AMYViD, Vizamyl, or Neuraceq), and which indicates the presence of beta-amyloid plaques in the cerebral cortex, within 5 years of enrollment;
• have normal levels of thyroid hormone (free T4) and thyroid-stimulating hormone (TSH);
• have normal levels of B12 and folate;
• have a designated study partner who will accompany the subject to all clinic visits and participate in the subject's clinical assessments; or
• be living in the community, including in an assisted living facility, but excluding long-term care nursing facilities.

Exclusion Criteria: All subjects enrolled in this trial must not:

• be unable to perform any of the assessments required for endpoint analysis;
• show signs of dementia other than AD, such as from AIDS (Acquired Immunodeficiency Syndrome), CJD (Creutzfeldt-Jakob disease), LBD (Lewy Bodies dementia), CVD (Cerebrovascular dementia), PSP (Progressive Supranuclear Palsy), MCI (multiple cerebral infarctions) or NPH (normal pressure hydrocephalus);
• have any other neurodegenerative disease;
• have a history of a seizure disorder;
• have clinically important abnormal screening laboratory values beyond AD;
• have any conditions that would contraindicate an MRI, such as the presence metallic objects in the eyes, skin, or heart;
• have any conditions that would contraindicate a PET scan;
• 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 macrohemorrhage as assessed by MRI;
• be currently using corticosteroids or similar powerful 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);
• be active listed (or expected to be listed) for transplant of any organ;
• be an organ transplant recipient;
• have a known hypersensitivity to dimethyl sulfoxide (DMSO).
• have a condition that is projected to limited life expectancy to < 1 year.
• have a sitting or resting systolic blood pressure >180 mm Hg or diastolic blood pressure >110 mm Hg at Screening;
• have a history of alcohol or drug abuse within the past 5 years.
• have been diagnosed with malignancy within the past 5 years, with the exception of curatively-treated basal cell carcinoma, squamous cell carcinoma, melanoma in situ or cervical carcinoma;
• be a female who is pregnant, nursing, or of childbearing potential while not practicing effective contraception (female subjects must undergo a urine pregnancy test at screening and on the infusion day prior to infusion);
• have any serious illness or any other condition that, in the opinion of the investigator, may compromise the safety or compliance of the subject or preclude successful completion of the study;
• have any serious illness or any other condition that, in the opinion of the investigator, may compromise the validity of the study (e.g., signs of stroke, traumatic brain injury (TBI), multiple sclerosis (MS), amyotrophic lateral sclerosis (ALS), and Parkinsonism;
• have participated in any investigational therapeutic or device trial within the past 5 years that the investigator feels would influence or affect the outcome of the study;
• be currently participating (or participated within the previous 30 days) in an investigational therapeutic or device trial;
• be positive for HIV, Syphilis and Hepatitis C; or
• be positive for Hepatitis B. If the subject tests positive for anti-HBc or anti-HBs, subject must be currently receiving treatment for hHepatitis B prior to infusion and remain on treatment throughout the study.