Introduction:: Rheumatoid arthritis (RA) is a chronic autoimmune disease characterized by joint inflammation, synovial hyperplasia, and cartilage degradation. Conventional systemic therapies often lead to off-target effects and inadequate drug concentrations at the disease site. Nanoparticle-integrated hydrogels have emerged as promising platforms for localized and sustained drug delivery in RA treatment. Methods:: This review summarizes recent advances (2020-2024) in the design of stimuliresponsive nanoparticle-loaded hydrogels for intra-articular RA therapy. Literature was sourced from PubMed, Scopus, and Web of Science using terms such as “nanoparticle hydrogel,” “RA drug delivery,” and “stimuli-responsive.” Articles were screened for novelty, in vivo validation, and mechanistic insight. Results:: Various polymers (e.g., chitosan, PEG, hyaluronic acid) and nanoparticles (e.g., PLGA, liposomes, AuNPs, CeO₂) have been integrated into hydrogels to enhance site-specific drug release. Mechanisms include pH-triggered swelling, ROS-labile bond cleavage, and MMPresponsive degradation. Case studies showed 50-60% reductions in TNF-α and IL-6 levels and improved joint histology in CIA models. Three-dimensional (3D)-printed hydrogels and photothermal systems further enhance precision targeting and retention. Discussion:: Stimuli-responsive hydrogels offer programmable, biocompatible, and minimally invasive treatment strategies. Nanoparticle integration enhances the therapeutic index by improving joint retention, reducing systemic exposure, and enabling real-time control. Challenges remain in scalability, regulatory clearance, and long-term biocompatibility. Conclusion:: Nanoparticle-integrated hydrogels represent a next-generation solution for localized RA therapy, offering controlled release, inflammation targeting, and reduced toxicity. Further preclinical and translational studies are warranted to support clinical adoption.
Joseph et al. (Mon,) studied this question.