Therapeutic Effects of miR-29b-Enriched Nanovesicles on Mitochondrial Injury and Neuroinflammatory Processes in Alzheimer's Disease.

Alzheimer's disease (AD) is defined by the accumulation of extracellular amyloid-β plaques and intracellular neurofibrillary tangles, which drive neuronal and synaptic impairment. In AD, the accumulation of protein aggregates leads to neuroinflammation, increased oxidative stress, and mitochondrial damage, resulting in neuronal loss and cognitive impairment. Emerging evidence highlights that microRNAs (miRNAs) modulate AD-related pathological pathways and may offer opportunities for therapeutic intervention. In this study, we investigated the therapeutic potential of microRNA-29b (miR-29b) delivered via small extracellular vesicles (sEVs) in an in vitro neuroblastoma model of AD. Four experimental groups were established using SH-SY5Y neuroblastoma cells: (1) untreated control cells, (2) Aβ-treated cells to model AD-like pathology, (3) cells treated with unloaded sEVs, and (4) cells treated with miR-29b-loaded sEVs (sEV-miR-29b). To evaluate treatment effects, we assessed markers of oxidative stress (ROS, LDH, SOD, MDA, GPX1), neuroinflammation (BDNF, ICAM1, TNF-α, NfL, MIF, VEGFA, MCP-1), mitochondrial dysfunction (Cytc, TFAM, PINK1, DNM1L), synaptic integrity (CPLX2, ROR1), and AD pathology (Amyloid-β, Total Tau, pTau181, pTau217). Our findings demonstrate that treatment with sEV-miR-29b attenuated Aβ-induced oxidative stress, reduced pro-inflammatory signaling, and improved mitochondrial homeostasis compared with Aβ-only and sEV-only groups. Moreover, sEV-miR-29b treatment partially restored synaptic protein expression and decreased pathological tau phosphorylation. These results indicate that miR-29b plays a regulatory role in neuroinflammation, oxidative stress, and mitochondrial function, suggesting that sEV-mediated delivery of miR-29b represents a promising therapeutic strategy for modulating AD-related neurodegenerative mechanisms. This study highlights the potential of miR-29b-loaded sEVs as a therapeutic approach for AD.