Intranasal delivery of engineered extracellular vesicles loaded with miR-206-3p antagomir ameliorates Alzheimer's disease phenotypes

<b>Rationale:</b> The level of miR-206-3p in the plasma and temporal cortex is increased in Alzheimer's disease (AD) patients. miR-206-3p antagomir injected into hippocampus ameliorates cognitive deficits by enhancing the level of BDNF. However, the trauma caused by brain injection and susceptibility to degradation limit its application. <b>Methods:</b> To overcome these challenges, we constructed engineered extracellular vesicles derived from mesenchymal stem cell (MSC-EVs) loaded with miR-206-3p antagomir (MSC-EVs-anta) by electroporation technology, and explored the therapeutic effects of MSC-EVs-anta delivered by intranasal administration on AD mice. Transcriptome sequencing and LC-MS/MS proteomic analysis were employed to disclose the mechanism underlying the attenuation of AD phenotypes by MSC-EVs-anta. <b>Results:</b> MSC-EVs-anta had favorable neuroprotection by promoting neurite outgrowth <i>in vitro</i>. Following intranasal administration, MSC-EVs-anta improved learning and memory deficits, promoted hippocampal neurogenesis and synaptic plasticity, and alleviated Aβ deposition. Compared with MSC-EVs or miR-206-3p antagomir alone, MSC-EVs-anta showed superior therapeutic effects. Mechanistically, MSC-EVs-anta significantly upregulated brain-derived neurotrophic factor (BDNF) in AD mice, and activated the BDNF/TrkB signaling pathway. The data from two-omics analyses demonstrated that the differentially expressed proteins and genes significantly regulated by MSC-EVs-anta were primarily enriched in the pathways involved in neurogenesis and synapse. <b>Conclusions:</b> Our findings highlight the intranasal administration of MSC-EVs-anta as a promising strategy for the treatment of AD.