| Dental implants are considered to be the third pair of teeth.After implant-supported prosthesis,patients can get well-pleased masticatory efficiency.Implants can delay alveolar bone absorption and improve the quality of life.A large scale of studies reported methods of modification of implant surface.However,compared with treatments of implant surface,few of studies reported the mechanism of implant osseointegration.This study is designed to evaluate the biological effects of lipoprotein receptor-related protein 5(LRP5)on osteogenic differentiation of bone marrow mesenchymal stem cells(BMSCs)through overexpression and inhibiton of LRP5 by adenovirus and lentivirus delivery system in vitro,and to explore the effects of gene modified BMSC sheets on implant osseointegration in vivo.BMSC sheets are attractive for cell-based tissue engineering.However,methods of culturing BMSC sheets are critically limited.In order to obtain intact BMSC sheets,a light-induced cell sheet method was used in this study.TiO2 nanodot films were coated with(TL)or without(TN)laminin-521.We investigated the effects of laminin-521 on BMSCs during cell sheet culturing.The fabricated BMSC sheets were subsequently assessed to study cell-sheet viability,reattachment ability,cell-sheet thickness,collagen type I deposition,and multi-lineage potential.The results showed that 1200ng/mL laminin-521 could promote the formation of BMSC sheets with good viability under hyperconfluent conditions.Moreover,BMSC sheets maintained their potential of osteogenic,adipogenic,and chondrogenic differentiation.In the following studies,1200ng/mL laminin-521 was used to develop BMSC sheets.Luciferase gene reporter and enhanced green fluorescent protein(EGFP)gene reporter that have been intensively performed on tumor cells are barely conducted in the implantology.This study was designed to corroborate the feasibility of lentivirus delivery of green fluorescent protein(GFP)and luciferase report genes for imaging BMSC-implant complexes in vivo.EGFP-and luciferase-expressing BMSC sheets were transplanted into one tibia of each rat.Results showed that cell sheets survived for almost 1 month after transplantation,and disappeared at 2 months.GFP signals could not be detected directly in vivo.Furthermore,we developed TiO2 nanodot coated implants and fabricated BMSC-TiO2 nanodot-implant complexes using light-induced cell sheet method.The results showed that TiO2 nanodot significantly promoted the adhesion and proliferation of BMSCs,and upregulated the expression of osteogenic genes(alkaline phosphatase(ALP),Osteocalcin(OCN),Collagen ?,bone morphogenic protein 2(BMP2),Runx2 and Osterix).In vivo studies,TiO2 nanodot surfaces could significantly improved osseointegrating functionality of BMSC sheets.Finally,we developed gene modified BMSC sheets through overexpression and inhibiton of LRP5 by adenovirus and lentivirus delivery system in vitro.The study showed that overexpression of LRP5 significantly promoted osteogenic differentiation of BMSCs and activated the classical Wnt signaling pathway.The osteogenic related genes(Runx2,Osterix,ALP,OCN,BMP2)were upregulated.These factors contributed to rapid implant osseointegration.Inversely,silence of LRP5 inhibited osteogenic differentiation of BMSCs and implant osseointegration.In this study,we reviewed and analysed the patient data of Stomatology Hospital Affiliated to Zhejiang University of Medicine from 2006 to 2011,the results showed that implant failure rate was related with age,gender,implant type,experience of doctors.The main cause for implant failure was peri-implantitis.The dentists should prevent the occurance of per-implantitis in the treatment,and reduce implant failure rate. |
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