Effect Of α-tricalium Phosphate And Calcium Hydrogen Phpsphate And Tricalium Silicate Bone Cement On ME3T3-E1CELLS

Experimental Objectives: This experiment is to mix tricalcium silicate (C3S) with composites ofcalcium phosphate system (α-tricalcium phosphate+calcium hydrogen phosphate) to produce calciumphosphate bone cement, to properly regulate physicochemical properties of the bone cement including thecuring time and degradation rate, to evaluate the cytotoxicity of the bone cement for mice osteoblastMC3T3-E1in vitro, and to study related gene expression of the cell in vitro.Experimental methods:(1) Preparation of composite bone cement: α-TCP powders were preparedwith a mechanical mixing method; C3S powders were prepared by coprecipitation. The composite bonecement were produced with various powders in different proportions. With the composite bone cementcolumn immersed in the simulated body fluid (SBF), the PHs of leach liquor and the degradation rates ofthe column were recorded in different time periods, and the microstructures of the column in the differenttime periods were studied by means of SEM and XRD.(2) Detection of the cellular levels: the cytotoxicityof the leach liquor for mice osteoblast MC3T3-E1was detected by means of MTT.(3) Detection of geneexpression levels: The expression levels of cell cycle related genes cyclin-dependent kinase inhibitor(Cdkn2b) and osteoblast’s differentiation markers (COL-I) were analyzed quantitatively by means of PCR.Experimental Results:(1) Curing time: As proportions of C3S increased, the curing times weregradually shortened.(2)The degradation rate and pH: The bone cement with composite C3S had a moderatedegradation rate. It had the minimum degradation rate when no C3S was added. As the proportion of C3Sadded increased, the degradation rate increased. The degradation rates of the composite bone cement withdifferent C3S proportions increased along with prolonged immersion time, and eventually were stabilized. As the immersion time is prolonged, the leach liquor turned to neutral pH from the original alkaline pH.(3)SEM and XRD: SEM and XRD results confirmed that hydroxyapatite generates on the surface of the curedcement.(4) Cytotoxicity and related gene expression: The results of cell culture showed that everyexperimental group had no cytotoxicity in vitro. Compared with the negative control group, theexperimental group with composite C3S indicated that the rate of cell proliferation had an apparentincreation.by designed extracts concentration treating.RT-PCR analysis showed C3S content performinhibition of Cdkn2b gene expression and stimulating COL-I gene expression.Experimental Conclusions: A proper proportion of C3S can shorten the curing time of the bone cementwith composite calcium phosphate (α-TCP+DCPD), change the PH and the degradation rate of the bonecement, and finally can have a good biocompatibility.