Covalent Organic Framework as a Novel Osteoinductive Biomaterial Promotes Osteogenic Differentiation of Bone Marrow Mesenchymal Stem Cells via Activation of Wnt/β-Catenin Pathway

Delayed healing and bone nonunion occur frequently after resection of bone tumors; therefore, it is necessary to search for novel osteoinductive materials. In recent years, due to the rapid development of tissue engineering research, the application of stem cells in regenerative medicine has gained much attention. This study aimed to examine the synthesis and material characterization of covalent organic framework (COF)-Imine by using a modified procedure. The cytotoxicity of COF-Imine to bone marrow mesenchymal stem cells (BMSCs) and its biocompatibility in mice were also investigated. In vitro experiments revealed that COF-Imine had no significant cytotoxicity to BMSCs, and in vivo studies indicated no obvious pathological damage to the major organs of the mice. The effect of COF-Imine on BMSC osteogenic differentiation and its molecular mechanism was also explored. We found that COF-Imine possesses the ability to promote osteogenic differentiation of BMSCs and to repair skull defects in rats; indicating the underlying mechanism associated with the activation of the Wnt/β-catenin pathway. In summary, these results not only shed light on the therapeutic mechanism of COF-Imine, but also provide the basis for developing an effective therapeutic approach for bone defects.