Mechanically enhanced composite hydrogel scaffold for in situ bone repairs

High-efficiency repair of critical bone defects isa pressing problem in clinical practice. However, most biological re-placement materials do not simultaneously satisfy the dual requirements of mechanical strength and cell compatibility. In this study, chitosan methacryloyl (CSMA) and ??-tricalcium phosphate (??-TCP) were subjected to photo-crosslinking to form the CSMA/??-TCP composite hydrogel, which has strong mechanical properties contributing to bone regener-ation. In addition, its scaffold can alter the morphology of bone marrow mesenchymal stem cells (BMSCs), promote their proliferation, enhance the expression of alkaline phosphatase (ALP), and augment the nodular deposition of cal-cium. Meanwhile, the expressions of osteogenic proteins (ALP, osteocalcin, and osteopontin) were upregulated and the regulatory mechanism of the Hippo signaling pathway was verified. Moreover, animal experiments have confirmed that CSMA/??-TCP has adequate biocompatibility and bone regeneration. These results demonstrate the immense po-tential of the CSMA/??-TCP composite hydrogel in bone regeneration therapy.