Osteoarthritis (OA) is characterized by cartilage degradation, inflammatory responses, and osteophyte formation. Matrix metalloproteinase 13 (MMP13) is a hallmark of OA development, and increased MMP13 expression is closely associated with extracellular matrix degradation. MMP13 expression varies significantly at different stages of OA progression. While cyclooxygenase 2 (COX-2) inhibitors are commonly used to treat OA, their long-term systemic administration increases the risks of adverse effects. Therefore, with the aim of achieving localized and responsive delivery of the COX-2 inhibitor celecoxib, the current study investigated an innovative MMP13-responsive micro-nano hydrogel microsphere system. Celecoxib-loaded cationic liposomes are non-covalently attached within the microsphere, enabling controlled drug release for OA treatment. In an OA environment with elevated MMP13 expression, the system is degraded via the action of MMP13 substrate peptide (MMP13sp), facilitating accelerated release of drug-loaded liposomes to improve the inflammatory microenvironment and treat OA rapidly. Compared to a phosphate-buffered saline solution with hyaluronidase (HAase), the prepared hyaluronic acid methacrylate microspheres HAMA/MMP13sp/Lipo@celecoxib exhibited rapid degradation in a solution containing a physiological concentration of MMP13/HAase, demonstrating specific enzyme responsiveness for precise anti-inflammatory drug release. The MMP13-responsive hydrogel microsphere system achieves intelligent and controllable drug release in OA, effectively decelerating disease progression and promoting articular cartilage repair.
Despite numerous attempts to engineer cartilage tissue in recent years, significant challenges remain regarding hyaline cartilage regeneration. One main reason is that the overactivated inflammatory response after injury suppresses inherent cartilage regenerative capabilities. Since the arthritic microenvironment is constantly changing during posttraumatic stress, an inflammatory diagnostic logic-based hydrogel for cartilage regeneration is developed for the first time through cross-linking of 4-arm poly(ethylene glycol)-vinyl sulfone (PEG-VS) and specific matrix metalloproteinase (MMP) 13-sensitive peptides. The hydrogel exhibits diagnostic logic to identify the pathological cue MMP13 and accordingly determine drug release kinetics in an inflammatory microenvironment. Additionally, multiphase therapeutic ability is designed to program different cargo release behaviors to match the inflammation-chondrogenesis cascade for better cartilage regeneration. Here, it is first proposed that MMP13 is a suitable diagnostic biomarker to modulate the inflammatory microenvironment in the early stage of cartilage injury. In vitro and in vivo studies show that the hydrogel has good injectability, on-demand anti-inflammation, and immunomodulation capabilities. Ultimately, loaded with multiple therapeutic factors, the hydrogel shows both microenvironmental modulation and chondrogenesis therapeutic ability, resulting in satisfactory hyaline cartilage regeneration. This study provides critical insight into the design and biological mechanism of both diagnostic and therapeutic ability-based cartilage tissue engineering strategies.
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