Extracellular vesicles as a liquid biopsy for amyotrophic lateral sclerosis: a systematic review and meta-analysis

BackgroundDefinitive diagnosis of amyotrophic lateral sclerosis (ALS) is only possible through a postmortem examination. Extracellular vesicles (EVs) have emerged as promising minimally invasive biomarkers for ALS, but studies vary widely in methodology and reproducibility. We conducted a systematic review and meta-analysis to evaluate the diagnostic potential of EV-associated proteins and RNAs in ALS. MethodsFollowing PRISMA guidelines, we searched PubMed and EMBASE from inception to October 15, 2025. Thirty-nine studies met inclusion criteria. Random-effects models were used for continuous outcomes, and diagnostic accuracy was assessed using hierarchical summary ROC and bivariate random-effects models. Publication bias was evaluated using Begg, Egger, and funnel plots. ResultsEV-associated TDP-43 was the most frequently studied protein. Meta-analysis of five studies showed a moderate but non-significant increase in ALS vs. controls (SMD = 1.30) with high heterogeneity (I{superscript 2} = 97.8%). Sixteen studies assessing EV-RNA biomarkers showed minimal overlap and limited independent replication. Diagnostic accuracy meta-analysis across 11 studies yielded moderate performance (AUC = 0.839). No publication bias was found across both meta-analyses. ConclusionsEV biomarkers for ALS show biological promise but are limited by methodological variability and insufficient replication. Standardized protocols, transparent data sharing, and independent validation are needed.