NO-Responsive Oleanolic Acid Self-Assembled Micelles Co-Loaded with BAY 11-7082 for Synergistic Chondroprotection and Anti-Osteoarthritis Therapy.

Osteoarthritis is an irreversible degenerative joint disease driven by sustained NF-κB-mediated inflammatory responses, and conventional intra-articular hyaluronic acid or small-molecule NF-κB inhibitors cannot achieve targeted on-demand treatment due to poor solubility, rapid clearance and lack of lesion microenvironment responsiveness. OA with inherent anti-chondrolytic activity can self-assemble into nanocarriers in water, yet it lacks stimuli-responsive capacity. Herein, we rationally designed and synthesized an OA-Der by covalently conjugating o-phenylenediamine fragments to the OA backbone. 1H NMR and HRESI-MS spectra fully verified the accurate chemical structures of intermediate and final OA-Der. Blank OA-Der micelles exhibited uniform spherical core-shell nanostructures (50-150 nm) under TEM and AFM, while pathological high NO triggered complete disassembly of micellar assemblies. We further co-assembled OA-Der with NF-κB inhibitor BAY 11-7082 to construct NO-responsive BAY@OA-Der supramolecular micelles. In vitro experiments using human C28/I2 chondrocytes with LPS-induced inflammatory injury demonstrated that BAY@OA-Der significantly improved cell viability and reduced apoptotic chondrocyte proportion. At mRNA and protein levels, the supramolecular micelle formulation remarkably suppressed NF-κB p65 phosphorylation, downregulated cartilage-degrading ADAMTS5, and upregulated ACAN compared with free BAY or blank OA-Der. Collectively, this natural bioactive self-assembled NO-responsive delivery platform achieves synergistic anti-inflammatory and matrix-protective effects by precisely releasing drugs at NO-overexpressed osteoarthritis inflammatory sites and offers an in vitro design strategy for osteoarthritis responsive delivery systems.