| Objective: Periodontitis is caused by plaque,a chronic infectious disease that occurs in the periodontal supporting tissues,which could lead to pathological changes such as gingival recession,periodontal pocket formation and alveolar bone resorption.The ideal therapeutic effect of periodontitis is to form the "new periodontal attachment",that is,to reconstruct the periodontal ligament-cementum structure.But clinical methods alone cannot achieve the ideal effect currently.Therefore,a new method for periodontitis needs to be found to achieve a better treatment.This study intends to use the principle of tissue engineering,which is widely used in the field of regenerative medicine,to prepare PDLSCs-PLGA composites for periodontal tissue regeneration.However,the efficacy of osteogenic differentiation of stem cells alone to repair bone defects remains to be verified;2D cultured cells may work poorly after implantation;the activity of PDLSCs inside the carrier is unknown and the effect of cell delivery of the composite remains unclear.To solve the questions above,we will modify the polymer and verify the effect of cell delivery in vitro,and then explore the repairation effects on experimental periodontitis in vivo,looking forward to providing a new idea for clinical periodontitis treatment.Methods: 1.The PLGA porous microspheres were subjected to silk fibroin and biomimetic mineralization modification.The morphology was observed by SEM and the elemental composition was analyzed by EDS.XRD and FTIR were used to analyze the modification.Nano Measurer software was used to calculate the average particle diameter and pore diameter.2.The CCK-8 method was used to detect the cytotoxkonicity of different delivery carriers.The optical microscope and the fluorescence spectrophotometer were used to detect the cell delivery and cell proliferation,respectively,and the confocal microscope was used to detect the cell activity inside the carrier.ALP activity detection and alizarin red staining experiments were used to verify the osteogenic differentiation in vitro.3.The experimental periodontitis model in rats was established by ligation and the high-sugar diet.Delivery carriers were transplanted into the alveolar bone defect by periodontal surgery.After treatment,the periodontal indexes(GM-CEJ,PD,GI,SBI)and inflammatory cytokines in GCF were measured,and the effect of bone regeneration was evaluated using the method of Micro-CT three-dimensional reconstruction.Results: 1.Preparation and characterization of biomimetic modified PLGA porous microspheres 1.1 According to the SEM images and the diameter analysis,the porous microspheres were suitable for cell proliferation and metabolism.1.2 Based on the results of SEM,EDS,XRD and FTIR,PLGA was successfully modified with silk fibroin and biomimetic mineralization.2.Biological evaluation of cell delivery carriers in vitro 2.1 The results of DNA proliferation and live-dead cell staining experiments exhibited that PDLSCs could proliferate inside the carrier and maintained good cell viability.2.2 The optical microscope images at different time points showed that cells could crawl out of the carrier,and could be fused with surrounding cells after 96 hours.2.3 The results of ALP activity detection and alizarin red staining showed that all of four carriers were not affected the osteogenic differentiation of PDLSCs in vitro.3.Repairation effect of cell delivery carriers on experimental periodontitis in rats 3.1 According to the periodontal index table,the efficacy of the PDLSC group was not satisfactory,but the indexes of the PLGA / SF / HA group were statistically different compared with the periodontitis group.3.2 The results of GCF inflammatory factors showed that,except for IL-10,inflammatory cytokines in cell delivery carrier groups showed a downward trend compared with the periodontitis group.3.3 The images of Micro-CT reconstruction showed that cell delivery carrier groups were better than PDLSCs group for periodontal tissue regeneration.Conclutions: 1.The PLGA porous microspheres(particle diameter 150 μm,pore diameter 25 μm)suitable for stem cells proliferation were prepared by double emulsion-solvent evaporation method,which were subjected to silk fibroin and biomimetic mineralization to prepare four different porous microsphere carriers.2.The cell delivery carriers had no adverse effects for PDLSCs on growth,proliferation and differentiation,and could achieve cell delivery.3.Compared with the periodontitis group,all of four kinds of porous microsphere carriers exhibited the effect of periodontal tissue repairing,in which the PLGA / SF / HA group performed the best. |
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