Abstract: BACKGROUND: Dextran hydrogel has become a popular tissue engineering material because of its good biocompatibility and injectability, and is extensively used in the repair of hard and soft tissues. However, in the repair of bone defects, pure dextran hydrogel still has insufficient bone formation ability in osteogenesis.  
OBJECTIVE: To construct a hydrogel material with dextran and modified mesoporous bioactive glass, characterize the material, and investigate its cell adhesion and bone formation ability in vitro.
METHODS: The dextran was oxidized and modified by sodium periodate to make it rich in aldehyde groups. After aminating and modifying mesoporous bioactive glass, the aminated mesoporous bioactive glass powder was added to the oxidized dextran solution and mixed evenly. Gelatin solution was added to prepare dextrangel-aminated mesoporous bioactive glass nanoparticles (GelDex-AMBGN) composite hydrogel. The bone marrow mesenchymal stem cells were separately inoculated in the oxidized dextran hydrogel and GelDex-AMBGN composite hydrogel. Simply cultured cells were consisted as controls. The cell biocompatibility was detected by Live/Dead fluorescent staining, scanning electron microscope, and CCK-8 assay. The Osteogenic property was detected by alkaline phosphatase staining, alizarin red staining, and immunofluorescence staining for osteocalcin.  
RESULTS AND CONCLUSION: (1) Live/Dead fluorescence staining results after co-culture for 3 days displayed that bone marrow mesenchymal stem cells in the two hydrogels grew well, maintained high cell viability, and the cell survival rate was higher than 90%. (2) After co-culture for 3 days, scanning electron microscopy results exhibited that bone marrow mesenchymal stem cells spread well on the surface of the two hydrogels. (3) CCK-8 assay results demonstrated that there was no significant difference in the cell proliferation viability of the three groups at 1, 3, 5, and 7 days after culture (P > 0.05). (4) The alkaline phosphatase staining showed stronger results in the composite hydrogel group compared with the oxidized dextran hydrogel and control groups after co-culture for 7 days. The calcium content after co-culture for 21 days was higher in the composite hydrogel group than that of the oxidized dextran hydrogel and control groups (P < 0.05). The immunofluorescence staining for osteocalcin and calcium content detection after co-culture for 21 days revealed stronger results in the composite hydrogel group compared with the oxidized dextran hydrogel group and the control group. (5) The results indicate that GelDex-AMBGN composite hydrogel has good biocompatibility and the osteogenesis ability.

Key words: hydrogel, dextran, oxidized dextran, mesoporous bioactive glass, biocompatibility, osteogenesis, bone defect