Neurology · Medical Literature
Efficacy and Safety of Mesenchymal Stem Cell Therapy for Alzheimer's Disease: A Systematic Review and Meta-Analysis.
Abstract
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.
Clinical relevance
In patients with primary Alzheimer's disease, does mesenchymal stem cell (MSC) therapy improve cognitive function, daily functioning, neuropsychiatric symptoms, biomarkers, or imaging outcomes compared to control, and what is its safety profile? __SNAPSHOT__ {"studyDesign":"Systematic review and meta-analysis (PRISMA 2020-compliant; PROSPERO-registered protocol CRD420261329891)","setting":"International; databases searched included PubMed, Cochrane Library, Embase, Web of Science, CNKI, and Wanfang from inception to March 1, 2026","sampleSize":"n=196 patients across 6 included clinical studies","population":"Adults with a primary diagnosis of Alzheimer's disease; specific inclusion criteria (e.g., severity stage, MMSE range, biomarker confirmation) not fully reported in the available abstract","intervention":"Mesenchymal stem cell (MSC) therapy (source, dose, route of administration, and number of infusions varied across included studies and are not individually reported in the abstract)","comparator":"Not explicitly stated in the abstract; comparator type (placebo, active control, or standard of care) not uniformly reported across included studies","primaryOutcome":"Cognitive function assessed by the Alzheimer's Disease Assessment Scale-Cognitive Subscale (ADAS-Cog) and Mini-Mental State Examination (MMSE) at 12–16 weeks and 24–26 weeks; additional outcomes included daily function, neuropsychiatric symptoms, biomarkers, imaging findings, and adverse events","followUp":"12–16 weeks and 24–26 weeks (as reported for cognitive outcome time points; maximum follow-up duration not reported)","fundingSource":"Not reported"}
Key findings
Across 6 clinical studies enrolling 196 patients, pooled meta-analysis demonstrated no statistically significant improvement in ADAS-Cog or MMSE scores at either the 12–16 week or 24–26 week time points following MSC therapy. Specific pooled standardized mean differences (SMDs), 95% confidence intervals, p-values, and heterogeneity statistics (I²) for these primary outcomes are not reported in the available abstract. Results for secondary outcomes — including daily functional scales, neuropsychiatric symptom inventories, CSF or blood biomarkers, and imaging findings — are not reported in the abstract. Adverse event data and GRADE certainty-of-evidence ratings for individual outcomes are not reported in the available abstract. Risk of bias was assessed using the RoB 2 tool; individual study-level risk-of-bias findings are not reported in the abstract. NNT and NNH cannot be calculated from the available data.
Practice implications
Based on the abstract alone, this meta-analysis found no statistically significant cognitive benefit of MSC therapy in Alzheimer's disease at 12–16 or 24–26 weeks of follow-up, as measured by ADAS-Cog and MMSE. The study did not establish clinical efficacy of MSC therapy for AD. Critically, only 6 studies with 196 total patients were included — a very small evidence base for definitive conclusions — and substantial heterogeneity in MSC source, preparation, dose, delivery route, and patient population is expected across trials but is not quantified in the abstract. It is not established whether any subgroups (by disease severity, MSC type, or route of administration) may derive differential benefit. The findings do not apply to specific MSC preparations or delivery approaches that were not represented in the included studies. The full manuscript should be consulted for GRADE certainty ratings, heterogeneity estimates, subgroup analyses, biomarker and imaging results, and the complete safety profile before drawing practice-level conclusions. This summary is based on an abstract only, which limits interpretive confidence. __LIMITATIONS__ Very small total sample size (n=196 across 6 studies), severely limiting statistical power and precision of pooled estimates.,Abstract-only availability precludes assessment of heterogeneity statistics (I²), GRADE certainty ratings, subgroup analyses, or individual study risk-of-bias profiles.,Expected high clinical heterogeneity in MSC source (bone marrow, umbilical cord, adipose, etc.), dosing regimen, delivery route (intravenous vs. intracerebroventricular vs. stereotactic), and patient severity stage across included trials.,Comparator arms across included studies are not standardized in the abstract (unclear whether all studies used placebo vs. active control or standard of care).,Short follow-up windows (12–26 weeks) may be insufficient to detect meaningful disease-modifying effects in a slowly progressive neurodegenerative condition.,Search extended to Chinese-language databases (CNKI, Wanfang), which improves comprehensiveness but raises potential concerns about reporting quality and publication bias in non-English literature.,Funding source not reported, precluding assessment of potential industry bias.,ADAS-Cog and MMSE are sensitive to practice effects and floor/ceiling effects in moderate-to-severe AD; they may not capture early or subtle biological effects of MSC therapy.,Absence of biomarker- or imaging-confirmed AD diagnosis requirement is not clarified in the abstract, raising potential diagnostic heterogeneity across studies.,The distinction between statistical non-significance and true absence of clinical effect cannot be drawn given the very small sample sizes. __BOTTOM_LINE_CATEGORY__ not_ready_for_clinical_application __BOTTOM_LINE__ This PRISMA-compliant meta-analysis of 6 clinical studies (n=196) found no statistically significant improvement in ADAS-Cog or MMSE scores with MSC therapy in Alzheimer's disease at 12–26 weeks. The extremely small evidence base, expected heterogeneity in MSC preparations and delivery methods, and short follow-up preclude definitive conclusions about efficacy or safety. MSC therapy for AD remains investigational and should not be adopted into clinical practice outside of well-designed, adequately powered clinical trials.