Efficacy and Safety of Mesenchymal Stem Cell Therapy for Alzheimer’s Disease: A Systematic Review and Meta-Analysis

Alzheimer's disease (AD) is the leading cause of dementia, and effective disease-modifying therapies remain limited. Mesenchymal stem cells (MSCs) have shown therapeutic potential because of their neuroprotective and immunomodulatory properties, but clinical evidence remains inconclusive. We systematically evaluated the efficacy and safety of MSC therapy in AD. Following the PRISMA 2020 guidelines and a PROSPERO-registered protocol (CRD420261329891), we searched PubMed, the Cochrane Library, Embase, Web of Science, CNKI, and Wanfang from inception to March 1, 2026. Clinical studies of patients with primary AD treated with MSCs were included. Outcomes covered cognition, daily function, neuropsychiatric symptoms, biomarkers, imaging findings, and adverse events. Standardized mean differences (SMDs) with 95% confidence intervals (CIs) were pooled using R. Risk of bias was assessed with the RoB 2 tool, and evidence certainty was assessed with GRADE. Six studies involving 196 patients were included. Overall analyses showed no significant improvement in Alzheimer's Disease Assessment Scale-Cognitive Subscale (ADAS-Cog) or Mini-Mental State Examination (MMSE) at 12-16 weeks or 24-26 weeks after MSC treatment versus placebo, with substantial heterogeneity. Dose-stratified analyses suggested significant benefits of low-dose MSCs on ADAS-Cog (SMD = -1.33, 95% CI: -2.35 to -0.31) and MMSE (SMD = 2.59, 95% CI: 0.52-4.66). MSC therapy significantly improved Alzheimer's Disease Cooperative Study-Activities of Daily Living (ADCS-ADL; SMD = 3.27, 95% CI: 1.79-4.75), but not Neuropsychiatric Inventory (NPI) or Quality of Life in Alzheimer's Disease (QOL-AD) scale. Biomarker analyses showed no significant overall effects on Aβ42 or total tau, although subgroup analyses suggested possible increases in Aβ42 and reductions in total tau at certain doses. Imaging data from two studies indicated potential protective effects on hippocampal atrophy. MSC therapy was generally well-tolerated, although intracerebroventricular administration was associated with more transient adverse events. Evidence certainty was low to very low for most outcomes. MSC therapy for AD appears feasible and relatively safe, with potential cognitive and disease-modifying effects. However, current clinical evidence remains insufficient to confirm its efficacy.