Research On Osteoimmunomodulation Of Mesoporous Bioactive Glass Loaded With FTY720

Bioactive glass(BG)has excellent osteoconduction and osteoinduction properties,and is an great norganic nonmetallic bone repair material.Among them,mesoporous bioactive glass is a good drug control release carrier because of its larger specific surface area and ordered mesoporous structure.It is reported that local application of fingolimod(FTY720)can promote osteogenesis through immune regulation.However,there is no ideal biomaterial for the sustained release of FTY720 in the bone defect areas.In this work,we intend to load FTY720 with mesoporous bioactive glass bone repair material to promote bone regeneration by regulating the local immune microenvironment.The sol-gel method combined with the organic template self-assembly technology successfully prepared mesoporous bioactive glass microspheres with good monodispersity.And successfully loaded FTY720,and obtained FTY720 loaded mesoporous bioactive glass microspheres(FTY720@MBGs).The immune micro-environment induced by materials stimulated polarization of macrophage and the effect of materials induced micro-environment on osteogenesis and osteoclastogenesis were discussed.Finally,the osteogenesis effect of FTY720@MBGs was verified through in vivo experiments.The specific research work and conclusions are as follows:(1)Based on the sol-gel method,combined with oil-water biphase delamination reaction system and organic template self-assembly technology,the micro-nano spherical bioactive glass were prepared with uniform morphology,good monodispersity,large specific surface area and ordered mesopores.Successfully loaded the small molecule drug FTY720,realizing the sustained release of the drug.(2)In order to explore the effect of the material on the polarization of macrophages,macrophages were cultured with extracts of MBGs and FTY720@MBGs.The results showed that the expression of anti-inflammatory factors in the FTY720@MBGs group was upregulated,and the expression of pro-inflammatory factors was down-regulated.It is confirmed that FTY720@MBGs promoted RAW 264.7 toward the M2 phenotype.(3)The effects of the cytokines secreted by the material regulating the polarization of macrophages on bone formation and osteoclast differentiation were studied.The results of in vitro experiments showed that the macrophage-conditioned FTY720@MBGs significantly upregulated the expression of bone formation-related genes of m BMSCs,the ALP activity of m BMSCs was obviously increased and more mineralized nodules.In addition,the macrophageconditioned FTY720@MBGs downregulated of osteoclast-related genes and suppressed osteoclast formation.(4)In order to verify whether the results of the in vitro cell experiment are consistent with the actual situation in vivo,an in situ bone defect experiment in rats was carried out.The results of immunohistochemical staining showed that FTY720@MBGs promoted the polarization of macrophages to M2.The in vivo experimental results showed that the bone defect area of the FTY720@MBGs group was almost completely filled with new bone,indicating the excellent osteogenic properties.Therefore,FTY720@MBGs can also regulate the polarization of macrophages in the in vivo environment and created a good immune environment for bone remodeling.In conclusion,the mesoporous bioactive glass loaded with FTY720 was successfully prepared.A large number of studies have proved that local delivery of FTY720 in mesoporous bioactive glass improves bone regeneration by synergistically immunomodulating osteogenesis and osteoclastogenesis.This study provides new strategies for designing smart cell-instructive biomaterials that can play a role in all bone healing processes from early inflammation to bone reconstruction.