Intra-articular injection of Erastin induces OA pathological progression as an experimental model

Background: Developing optimal osteoarthritis (OA) models is critical for therapeutic advancement. While ferroptosis is linked to OA pathogenesis, validated models for studying ferroptosis in OA remain scarce. Methods: In vitro: Mouse/C28I2/human chondrocytes were treated with 10 μM Erastin to assess ferroptosis, inflammation, extracellular matrix degradation, senescence, and antioxidant responses. OA patient and neonatal mouse cartilage explants were cultured ± Erastin (48 h) for Safranin O/IHC analysis. In vivo: 72 C57BL/6J mice (8-week-old) were divided into: (1) Destabilized medial meniscus (DMM) surgery group (Sham: contralateral knee); (2) 1 mg/kg Erastin intra-articular injection; (3) 10 mg/kg Erastin injection. Tissues were collected at 4/8/12 weeks for micro-CT and histology analysis (n=8/group/timepoint). Results: Erastin triggered ferroptosis, senescence, inflammation, and extracellular matrix degradation in mouse/C28I2/human chondrocytes, alongside NRF2 pathway activation and suppressed extracellular matrix synthesis. In cartilage explants (mice/OA patients), Erastin reduced COL2A1 and elevated MMP13 (IHC). In vivo, OARSI scores (Safranin O) and synovitis scores (H&E) increased significantly in DMM and Erastin (1/10 mg/kg) groups vs. Sham. IHC confirmed GPX4/COL2A1 downregulation and MMP13 upregulation in treated groups. Conclusions: A single intra-articular Erastin injection induces chondrocyte degeneration and cartilage damage mimicking human OA, offering a stable, simplified model compared to surgically complex DMM. This approach directly targets ferroptosis pathways, enabling precise mechanistic studies and streamlined preclinical testing of anti-ferroptosis therapies.