Abstract Neuroinflammation is central to the progression of neurodegenerative diseases (NDs), with microglia contributing through the release of pro-inflammatory and oxidative mediators. Although quercetin (Que) possesses potent anti-inflammatory and antioxidant properties, its clinical application is limited by poor solubility and bioavailability. Umbilical cord mesenchymal stem cells (UC-MSCs)-derived exosomes (Exo) offer a promising delivery system to enhance Que efficacy. This study investigated the anti-inflammatory effects of Que-loaded Exo (Que-Exo) using an in vitro neuroinflammation model. Exo were isolated from UC-MSC-conditioned media via ultracentrifugation and loaded with Que through sonication. Characterization of Exo and Que-Exo was performed using dynamic light scattering, zeta potential analysis, transmission electron microscopy, and western blotting. In vitro release and cellular uptake studies assessed Que-Exo release profiles and their internalization by HMC3 microglial cells. Neuroinflammation was induced in HMC3 cells using lipopolysaccharide (LPS). The effects of Que-Exo on pro-inflammatory cytokine and enzyme expression, nitric oxide (NO) production, and inflammatory signaling pathways were evaluated using flow cytometry, the Griess assay, and western blotting. In vitro release from Que-Exo demonstrated improved stability and controlled delivery, while fluorescence imaging confirmed efficient uptake of Que-Exo by HMC3 cells. Mechanistically, Que-Exo inhibited NF-κB nuclear translocation, a key regulator of pro-inflammatory mediator transcription. Que-Exo pretreatment significantly reduced TNF-α, IL-6, iNOS, and COX-2 expression and suppressed NO synthesis in LPS-stimulated cells. Overall, Que-Exo exhibited superior anti-inflammatory activity compared to Exo and free Que, highlighting the synergistic effect of exosomal delivery in enhancing Que bioavailability and therapeutic efficacy against neuroinflammation. Graphical Abstract
Osman et al. (Tue,) studied this question.