 This is a Phase IIa multi-center, randomized, single-blind, placebo-controlled, crossover study in subjects with mild to moderate dementia due to Alzheimers disease. Only the subject and their caregiver will be blinded to the study treatment. The study will consist of two cohorts of subjects 20 subjects per cohort, randomized in a 1:1 allocation to receive active study drug or placebo. Cohort 1 will receive a single intravenous dose of hMSCs of 1.5 million cells per kilogram body weight on their Study Day 1, and Cohort 2 will receive equal volume of Lactated Ringers Solution on their Study Day 1. At the six-month time point for each subject after their first infusion, Cohort 1 will receive a single intravenous dose of Lactated Ringers Solution and Cohort 2 will receive a single intravenous dose of hMSCs at 1.5 million cells per kilogram of the subjects body weight. Approximately 40 subjects will be enrolled in this study. An independent Data and Safety Monitoring Board will conduct periodic safety reviews. 