hUC-MSC-derived exosomes ameliorate Alzheimer's disease pathology through lncRNA-9969-mediated multi-target protection involving neuronal autophagy and microglial modulation.

backgroundAlzheimer's disease is characterized by intertwined pathologies including neuroinflammation, driven by microglial dysfunction, and metabolic disturbances such as lipid dyshomeostasis. Mesenchymal stem cell-derived exosomes (MSC-Exos) hold therapeutic promise, Still, it is unknown whether they can simultaneously address these co-occurring impairments via specific molecular cargos, such as long non-coding RNAs (lncRNAs).

methodsTranscriptome sequencing of exosomes derived from human umbilical cord mesenchymal stem cells (hUC-MSCs) revealed high expression of the long noncoding RNA ENST00000629969 (hereinafter referred to as lncRNA-9969). We isolated exosomes from hUC-MSCs (WT-Exo) and established human umbilical cord blood mesenchymal stem cells stably knocked down for lncRNA-9969 via siRNA, from which corresponding exosomes (KD-Exo) were isolated. Cross-species analysis identified the mouse homolog of lncRNA-9969 as ENSMUST00000200021 (hereinafter referred to as lncRNA-0021). Cellular experiments employed an Aβ₂₅₋₃₅-induced SH-SY5Y cell model to evaluate the protective effects of exosomes. In animal experiments, 6-month-old APP/PS1 mice received biweekly tail vein injections of WT-Exo or KD-Exo for 4 weeks. Phenotypic and mechanistic analyses were subsequently conducted using the Morris water maze, Western blot, immunofluorescence, qPCR, and transmission electron microscopy.

resultsIn Aβ-injured SH-SY5Y cells, WT-Exo significantly attenuated cellular damage and promoted Aβ clearance, whereas the protective effect of KD-Exo was markedly reduced. In APP/PS1 mice, WT-Exo treatment significantly improved spatial memory deficits and upregulated hippocampal expression of synaptic proteins synaptophysin (Syn) and brain-derived neurotrophic factor (BDNF). Molecular mechanism studies demonstrated that lncRNA-0021 directly binds mmu-miR-6361. Through this ceRNA mechanism, exosome-delivered lncRNA activated the mTOR/p70S6K autophagy pathway, regulated lipid metabolism-related genes, promoted microglial polarization toward the protective M2 phenotype, and suppressed pyroptosis. These beneficial changes were not observed in the KD-Exo-treated group.

conclusionshUC-MSC-derived exosomes exert neuroprotective effects by delivering functional lncRNA-9969. Its highly conserved homolog in mice, lncRNA-0021, achieves coordinated multi-target regulation of neuroinflammation, pyroptosis, and metabolic disturbances by sequestering miR-6361 and activating downstream signaling pathways. This study elucidates the central role of exosomal lncRNAs in AD pathology and provides new insights for developing RNA-based multi-target therapeutic strategies.