A novel BMSCs/GelMA-ACMMA composite hydrogel with tunable viscoelasticity promotes growth plate cartilage repair via the Piezo1-ROCK pathway

Growth plate injuries in children and adolescents often lead to bone bridge formation, resulting in limb deformities due to the limited self-repair capacity of the growth plate. The limitations of traditional treatments prompted interest in the role of the extracellular matrix (ECM) and mechanical environment in tissue repair. Recent research showed that 3D hydrogels could mimic ECM to regulate mesenchymal stem cells (MSCs) differentiation, with MSCs sensing matrix viscoelasticity via Piezo1 and responding through the ROCK signaling pathway. This study aimed to develop a 3D biomimetic hydrogel composed of acellular cartilage matrix methacryloyl (ACMMA) and gelatin methacryloyl (GelMA), with adjustable viscoelasticity via blue light crosslinking time. Hydrogels with low (5 s) and high (20s) modulus were fabricated and loaded with bone marrow mesenchymal stem cells (BMSCs). Results demonstrated that the 5 s hydrogel promoted chondrogenic differentiation and inhibited osteogenesis, effectively preventing bone bridge formation and enhancing growth plate repair in vivo . Mechanistic studies confirmed that the 5 s group did not activate the Piezo1-ROCK pathway, supporting its role in chondrogenic differentiation.