The Effect Of Ionic Products From Mesoporous Bioactive Glasses Dissolution On The Proliferation, Differentiation And Gene Expression Of Rat Osteoblast

Objectives:Highly ordered mesoporous bioactive glasses 80S(Mesoporous Bioactive Glasses MBGSOS) is designed and prepared by Yanxiaoxia et al from Fudan University,using non-ionic block copolymers as structure-directing agents through an evaporation-induced self-assembly(EISA) process.Recently,the research show the superior bioactivity and satisfactory biocompatibility of MBG80S as well as excellent adsorption and releasing properties to the protein like rhBMP-2 and satisfactory biocompatibility and adhesion to osteoblast.The aim of our study is to study the dissolution of MBG in Minimum Essential Medium and further explore the interaction between such ionic products and osteoblast by investigating the differentiation and proliferation of osteoblast and the related gene expression,from which a possible mechanism of the stimulatory effect of the ionic products of MBG on osteoblast differentiation is proposed.Methods:In the first part of the experiment,MBG was synthesized and soaked in Minimum Essential Medium(MEM),osteoblasts were isolated and treated with control MEM and MBG conditioned MEM(at concentration of 0.0625%,0.125%,0.25%,0.5%,1%).Cell proliferative capacity was quantified by using the 3-(4,5-dimethylthiazol-2-yl)-2,5- diphenyltetrazolium bromide(MTT) assay.Alkaline phosphatase(ALP) activity was measured with p-nitrophenol-phosphate(pNPP) as substrate.In the second part,RT-PCR was used for gene expression analysis of osteoblast, including IGF-2(insulin-like growth factor-2 ),Cbfal(core-binding-factor-alphal-1), Fibronectin,Osterix and osteocalcin.ELISA assay was applied to determine the protein concentration of unbound IGF-2,a known bone mitogenic growth factor,and IGFBP-3,an IGF-2 carrier protein,both in supernatant and cellular lysates.Resault:1.The ALP activity was significantly higher for MBG conditioned osteoblasts compared to control unstimulated osteoblasts,at concentration 0.0625,0.125,0.25% (P＜0.01).Cell proliferation is unaffected and the results show no significant differences compared to control untreated osteoblasts.2.After treated by MBG released ions,the mRNA of IGF-2,Cbfal,Fibronectin, Osterix and Osteocalcin was stimulated and increased to 126%,217%,201%,162% and 160%,respectively.Additionally,the concentration of unbound IGF-2 protein and IGF bind protein 3(IGFBP-3) was increased to 175%and 237%,respectively, showing significant differences.Conclusion:In conclusion,our data suggest that the ionic products of MBG dissolution may induce osteogenic differentiation of osteoblast.Moreover,after treated by MBG released ions,the mRNA of IGF-2,Cbfal,Fibronectin,Osterix and Osteocalcin which were critical transcription factors for proliferation,differentiation, mineralization and adhesion was stimulated.The amount of unbound IGF-2,along with its carder protein IGFBP-3,was increased,It is anticipated that MBG will be potentially useful as novel tissue-engineering scaffolds in bone regeneration.