Mechanically enhanced composite hydrogel scaffold for in situ bone repairs.

High-efficiency repair of critical bone defects is a pressing problem in clinical practice. However, most biological replacement materials do not simultaneously satisfy the dual requirements of mechanical strength and cell compatibility. In this study, chitosan methacryloyl (CSMA) and β-tricalcium phosphate (β-TCP) were subjected to photo-crosslinking to form the CSMA/β-TCP composite hydrogel, which has strong mechanical properties contributing to bone regeneration. 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 calcium. 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/β-TCP has adequate biocompatibility and bone regeneration. These results demonstrate the immense potential of the CSMA/β-TCP composite hydrogel in bone regeneration therapy.