A Study On Degradable Polymer Nanoparticle System For Bone And Joint Infection And Osteogenic Ability

OBJECTIVE Antibiotic-loaded bone cement beads are the primary means of topical medication for bone related infection.However,they have the following shortcomings:(1)not biodegradable materials,need a secondary surgery to remove;(2)the drug burst and antibiotic resistance to reduce the clinical application of the effect;(3)bone and joint infections are often accompanied by bone resorption and bone loss,resulting in severe infectious bone defects,and antibiotic bone cement beads can not play in the anti-infection at the same time play a role in promoting bone repair.In this paper,based on the shortcomings of the above-mentioned antibiotic bone cement beads,the preparation method of S/O/Ns was carried out to fabricate bio-biodegradable PLGA microspheres loading Strontium Ranelate(SR)or aspirin(ASP),and can be self-assembled by hydroxyapatite nanoparticles(HANPs)with enhanced bone properties or silver nanoparticles(Ag NPs)with anti-infective properties.Evaluate its biological safety in vitro and discuss its antibacterial properties and osteogenesis performance under circumstance of the different combinations of ingredients.In order to solve the clinical problems from the local point of view,for the treatment of bone and joint infection and infectious bone defects to provide new means.MATERIALS AND METHODS 1.PLGA microspheres loading SR and self-assembled HANPs(SR-PM-HA)were prepared by S/O/Ns method.Scanning electron microscopy(SEM)was used to observe the surface morphology.The encapsulation efficiency and drug release were determined by high performance liquid chromatography(HPLC).CCK-8 was used to detect the cell proliferation curve.ALP staining was used to qualitatively osteogenic differentiation.RT-PCR was used to detect osteogenesis-related genes.2.PLGA microspheres loading SR and self-assembled Ag NPs and HANPs(SR-PM-Ag-HA)were prepared by S/O/Ns method.The colonies were counted and the antibacterial efficiency was determined.The fluorescence intensity of bacteria was observed by laser confocal microscopy.Crystal violet dyeing quantitative biofilm formation.CCK-8 detection showed cell proliferation curve.ALP staining qualitative osteogenic differentiation.The osteogenic genes were determined by RT-PCR.3.PLGA microspheres(ASP-PM-Ag),which were loaded with ASP and self-assembled Ag NPs.SEM was used to observe the surface morphology.The encapsulation efficiency and drug release were determined by high performance liquid chromatography(HPLC).CCK-8 detection showed cell proliferation curve.ALP staining qualitative osteogenic differentiation.The osteogenic genes were determined by RT-PCR.The colonies were counted and the antibacterial efficiency was measured.The fluorescence intensity of bacteria was observed by laser confocal microscopy.Crystal violet dyeing quantitative biofilm formation.RESULTS 1.Through the preparation method of S/O/Ns,SR can be successfully encapsulated into PLGA microspheres,and HANPs can be self-assembled to the surface of microspheres.SR can be released with PLGA degradation and no burst release is observed.SR-PM-HA has no toxic effect on MC3T3-E1 cells and can significantly stimulate proliferation.At the same time,it can significantly up-regulate the osteogenesis-related genes of MC3T3-E1 cells.2.The microspheres with self-assembled Ag NPs can significantly inhibit the adhesion of MRSA and S.epidermidis and the biofilm formation,and have high bacteriostatic efficiency,but not significantly promote osteogenic differentiation.3.ASP can be released by the degradation of PLGA slowly,there is no burst phenomenon.ASP-PM-Ag had no toxic effect on cells,and 5% drug-loaded ASP-PM-Ag could significantly stimulate the proliferation of MC3T3-E1 cells,and significantly up-regulated its osteogenesis-related genes.5%ASP-PM-Ag significantly inhibited MRSA adhesion and biofilm formation,with high antibacterial efficiency.CONCLUSIONS 1.SR-PM-HA microspheres have good biocompatibility,good encapsule efficiency and good drug release performance.It can stimulate MC3T3-E1 cell proliferation,and can promote its osteogenic differentiation.2.The microspheres with self-assembled Ag NPs showed good biosafety,and could significantly inhibit the adhesion of MRSA and S.epidermidis and the formation of biofilm,showing high antibacterial efficiency and could not promote the proliferation of MC3T3-E1 cells Osteogenesis differentiation.3.ASP-PM-Ag microspheres have good biological safety and good drug release performance.5% ASP-PM-Ag can stimulate the proliferation of MC3T3-E1 cells,and can promote its osteogenic differentiation.It can significantly inhibit the adhesion of MRSA and biofilm formation,showing a high bacteriostatic efficiency.