Oral Milk-Derived Extracellular Vesicles: A Promising Drug Delivery System for Neuroinflammatory Diseases.

Oral drug delivery is the most patient-friendly and safest approach for disease treatment; however, the bioavailability of macromolecular drugs and poorly soluble small molecules is severely limited by gastrointestinal degradation and the blood-brain barrier (BBB). Here, we developed a cost-effective, chitosan-based isolation method to efficiently isolate milk-derived extracellular vesicles (mEVs), which exhibit good stability in the gastrointestinal tract and intrinsic BBB-penetrating capability. Biodistribution studies showed that mEVs were absorbed in both healthy and experimental autoimmune encephalomyelitis (EAE) mice, with increased CNS accumulation under neuroinflammation, especially in oligodendrocytes and neurons. To address the poor stability and bioavailability of ellagic acid (EA) and to explore the therapeutic potential of mEVs in neuroinflammation treatment, we encapsulated EA and interferon-β (IFN-β) into mEVs and evaluated their therapeutic effects in experimental autoimmune encephalomyelitis (EAE) and lipopolysaccharide-induced neuroinflammation models. The results showed that mEV@IFN-β and mEV@EA significantly relieved disease progression and improved neuroinflammation compared to free drugs, with enhanced stability and bioavailability. Overall, our study findings establish mEVs as an efficient oral delivery platform capable of overcoming biological barriers for treating neuroinflammatory diseases, with the chitosan-based isolation method offering a scalable production approach.