Orally delivered, pH-resistant dual coated extracellular vesicles restore intestinal barrier function and suppress colitis

Oral therapy for inflammatory bowel disease (IBD) requires drug formulations that can withstand gastrointestinal stress and achieve localized action at the inflamed mucosa, yet existing extracellular vesicles (EVs)-based or small-molecule approaches often fail due to poor stability and limited colonic delivery. This study aimed to develop a dual-coated oral delivery platform that enhances gastrointestinal stability and targeted drug release. We engineered macrophage-derived EVs sequentially coated with a cationic lipid and sodium alginate (SA) to encapsulate 5-aminosalicylic acid (5-ASA). This stepwise surface charge-switching strategy preserved EV identity, conferred resistance to acids and enzymes, and enabled delayed uncoating at colonic pH. In a gastrointestinal-mimicking Caco-2-THP-1 co-culture model, dual-coated EVs (DCEVs) exhibited enhanced epithelial uptake, transepithelial transport, and macrophage delivery compared to unmodified EVs. In a dextran sodium sulfate (DSS)-induced colitis model, 1,2-dioleoyl-3-trimethylammonium-propane (DOTAP) facilitated endosomal escape and SA enabled timed release, resulting in increased colonic exposure, significant recovery of colon length, restoration of intestinal tight junctions, suppression of pro-inflammatory cytokines, and increased IL-10 expression. Collectively, these results demonstrate that a sequential coating strategy can effectively integrate EV-mediated immunomodulation with pharmacologic therapy, providing a pH-stable oral EV platform for localized treatment of IBD.