Preparation And Performance Study Of Composite Microgel Bone Powder For Tumor Suppression And Bone Defect Repair

The repair and treatment of tumor bone defects is a thorny problem to be solved urgently in clinical medicine.The development of new bionic bone graft materials with the ability to inhibit the proliferation of residual tumor cells after tumor resection,good biocompatibility,good osteogenic ability,and the ability to adapt to the filling of irregular defect areas will have great clinical significance and social value.Firstly,cerium（Cerium,Ce）and selenium（Selenium,Se）co-doped mesoporous bioactive glass nanospheres(M_{x Ce/y Se})were prepared by the organic template method.The regulatory effects of M_{x Ce/y Se} on the cell behavior of osteosarcoma cells MG-63 and human bone marrow mesenchymal stem cells h BMSC were studied.Secondly,M_{x Ce/y Se} and recombinant collagen（Recombinant Human Like Collagen,HLC）were dissolved in sodium alginate（Sodium Alginate,SA）solution.The composite microgel bone powder was synthesized by calcium ion chelation under the electrostatic field,and its regulatory action on tumor cell behavior and its effect to inhibit cancer were studied.Finally,the inhibitory effect of microgel bone powder on osteosarcoma and the repair of defective bone were studied through animal experiments.The main research contents and conclusions of this paper are as follows:（1）Preparation and performance study of Ce and Se co-doped mesoporous bioactive glass nanospheres M_{x Ce/y Se}.The M_{x Ce/y Se} were synthesized by organic template technology for the first time.The cytotoxicity analysis of h BMSCs and MG-63 cells cultured with different concentrations of M_{x Ce/y Se} extract showed that in all samples,when the cell survival rate of MG-63 cells cultured with M_3%Ce/3%Se extract was less than 10%,the cell survival rate of h BMSCs was more than 90%,indicating that M_3%Ce/3%Se had the ability to inhibit the proliferation of cancer cells and promote the growth of normal bone cells.The physical and chemical characterization analysis of the sample shows that M_3%Ce/3%Se was mesoporous nanospheres（particle size about 300 nm,pore size about 2-5 nm）.Through the mineralization experiment in vitro,it was found that M_3%Ce/3%Se had good apatite formation ability in vitro and good biological response ability.（2）Synthesis and performance study of composite microgel bone powder S-H-M_3%Ce/3%Se.A new composite microgel bone powder S-H-M_3%Ce/3%Se was prepared by M_3%Ce/3%Se with HLC in SA solution and chelating with calcium ions under the electrostatic field.It was found that Ce and Se could be released programmatically in tumor microenvironment medium（p H=6.5）and normal humoral environment medium（p H=7.4）,creating favorable conditions for tumor inhibition and bone defect repair.The cytotoxicity analysis of S-H-M_3%Ce/3%Se extract on model cells showed that with the increase of x value,the cell survival rate of MG-63 cells cultured with S-H-M_3%Ce/3%Se gradually decreased,and the survival rate of h BMSCs increased first and then decreased;when two kinds of cells were cultured with S-H-0.35M_3%Ce/3%Se extract,it could effectively killed MG-63 cells and promoted the growth of h BMSCs.The apoptosis of MG-63cells cultured with S-H-M_3%Ce/3%Se extract and the production of reactive oxygen species（ROS）were analyzed.It showed that the reason for inhibiting the proliferation of MG-63 cells might be that Se element contained in S-H-M_3%Ce/3%Se stimulated a large number of ROS production in MG-63 cells,which induced the apoptosis of MG-63 cells.（3）Histological study of composite microgel bone powder S-H-M_3%Ce/3%Se.The osteosarcoma model of nude mice was established,and S-H-M_3%Ce/3%Se was implanted into the edge of the tumor for treatment.After histological analysis of tumor tissue,it was found that the production of ROS and the number of apoptosis increased with the increase of M_3%Ce/3%Se concentration in S-H-M_3%Ce/3%Se.It was concluded that S-H-M_3%Ce/3%Se degraded in the acidic microenvironment of tumor and released Se element,which stimulated MG-63 cells to produce a large amount of ROS,induced tumor cell apoptosis and inhibited the growth of tumor cells.The rabbit knee osteochondral defect model was established at the same time.The histological analysis of the repaired bone showed that compared with the S-H group and the blank group,the repaired bone of the S-H-M_3%Ce/3%Se group had less fibrous tissue,more cartilage tissue and the formation of new bone tissue,which proved that S-H-M_3%Ce/3%Se had excellent ability to promote new bone formation.