Experimental Study On Bone Regeneration With BMSCs Accelerated By G-C₃N₄/rGO Of Novel Light-sensitive Material

BACKGROUNDWith the rapid development of transportation,infrastructure,industry and agriculture,the number of bone injuries were being increased.At present,the methods of bone repair mainly included autologous bone transplantation,allogeneic bone transplantation and xenogeneic bone transplantation.Autologous bone graft was the "gold standard" for the treatment of bone defects currently,but the main drawback were that the sources were limited,causing donor bone destruction and bone loss.Allogeneic and xenogeneic bones can lead to immune rejection and spread diseases.Bone marrow mesenchymal stem cells(Bone marrow mesenchymal stem cells,BMSCs)were extremely important seed cells for the characteristics of wide source,convenient operation and multi-directional differentiation.However,how to rapidly and effectively amplify and induce BMSCs in vitro and vivo was an urgent problem which need to be solved.Graphite phase carbonitride(g-C3N4)were non-metallic photocatalyst capable of generating photocurrent under visible light,but g-C3N4 photogenerated electrons and holes had a high recombination rate,which made the photocatalytic ability not particularly desirable.Therefore,this study found that graphene had superior electrochemical properties to enhance photochemical catalytic ability,resulting in highly efficient and stable photocurrent to stimulate and promote osteogenesis in BMSCs.METHODSThe g-C3N4/rGO were obtained by graphite powder and melamine under high-temperature calcination,and the properties of this material were analyzed.BMSCs were extracted from the bone marrow of SD rats,with passaging,purifying and expanding.After flow cytometry of BMSCs,g-C3N4/rGO were co-cultured with BMSCs,MTT,alkaline phosphatase activity assay,alizarin red staining,RT-qPCR and WB were detected for Osteogenic effect in vitro.16 SD female rats were randomly divided into blue light material group,blue light non-material group,dark material group and dark non-material group.Materials and cells were drilled in the femoral condyle respectively.When the rats were sacrificed for 8 weeks,the intact femurs were taken for Micro-CT analysis.RESULTSThe analysis of material property showed that the g-C3N4/rGO had a tighter layered stacking structure.It did not affect the crystal form and structure of g-C3N4 with adding rGO,but improving the utilization of visible light and photocatalytic ability in g-C3N4/rGO.The BMSCs were successfully cultured and passaged,the results of flow cytometry showed that the positive surface antigens were CD29(90.7%)and CD106(89.3%),the negative surface antigens were CD34(2.38%)and CD45(0.491%).MTT experiments confirmed that g-C3N4/rGO had no obvious toxicity to cells,alkaline phosphatase activity,alizarin red staining,RT-qPCR and WB had more obvious osteogenesis in blue light material group than dark material group.In vivo experiment,there was no significant difference between blue light material group and dark material group,however,the results were statistically different between blue light material group and the blue light non-material group,and the results were same to dark material group and dark non-material group.CONCLUSIONSg-C3N4/rGO had more effective photoelectric conversion ability;in vitro,g-C3N4/rGO irradiated by high-intensity blue LED lamp could stimulate photocurrent to promote rapidly osteogenic effect with BMSCs;in vivo experiments,the g-C3N4/rGO in the blue light material group and the dark material group promoted the osteogenesis effect,but there was no statistically significant difference.