Abstract The management of osteoarthritis (OA) and osteochondral defects faces challenges due to heightened catabolic activity from pro‐inflammatory mediators and a lack of reparative cells. Transforming growth factor β1 (TGFβ1) plays a crucial role in cartilage maintenance and cellular recruitment, making it a promising therapeutic target. However, the high cost and unpredictable effects of exogenous TGFβ1 limit its clinical application. Notably, TGFβ1 is primarily found in a latent form within joint tissues, especially during early injury stages. This study proposes that activating endogenous TGFβ1 may serve as an effective treatment strategy. We demonstrate that an ascorbic acid (AA) and ferric chloride (AA/Fe) Fenton reaction system can activate latent TGFβ1 in knee joint tissues. Treatment with AA/Fe‐activated synovial fluid protects chondrocytes from interleukin1β‐induced damage and enhances chemotactic responses in joint tissues. Intra‐articular AA/Fe injections in rats significantly phosphorylated SMAD2/3 and reduced cartilage degradation. Additionally, we developed poly(lactic‐co‐glycolic acid) microspheres for sustained AA/Fe release within a thermosensitive or photocrosslinkable hydrogel, showing high biocompatibility. These formulations effectively prevented cartilage degeneration and promoted osteochondral repair. Our findings confirm that AA/Fe reliably activates endogenous TGFβ1, providing a novel cell‐free and cost‐efficient treatment approach for OA and osteochondral defects.
Liao et al. (2025) studied this question.