Effect Of Novel Lithium Doped Calcium Phosphate Cement On Osteoblast Proliferation And Differentiation

OBJECTIVE:To research physical and chemical properties of novel lithium chloride/calcium phosphate cement(Li/CPC), while studying biological activity in vitro. To preliminarily explore the effect of Li/CPC on osteoblast proliferation and differentiation.METHODS:Materials science experiments: calcium phosphate cement(CPC) served for the control group, different lithium content of Li/CPC as the experimental group, to detect the physical and chemical properties of bone cements and biological activity in vitro. Gillmore was used to measure the initial and final setting time of the cements, Micro-computed tomography (Micro-CT) was used to caculated pore size distribution and porosity of materials, electronic static and dynamic universal material testing machine was used to tested compressive strength of materials, the morphology of the cements was examined by scanning electron microscopy(SEM), the phase constitution and structure were determined by X-ray diffraction and Fourier-transform infrared spectroscopy.Cells science experiments:bone cements and MC3T3-E1 cells were co-cultured in vitro. Adhesion and growth morphology of cells on bone cement surface was observed by SEM. Staining of cytoskeletal proteins was examined by fluorescent electronic microscope. Cell proliferation was quantified by the CCK-8. Alkaline phosphatase (ALP) activity was tested by ALP assay kit. Ability of osteogenic differentiation and extracellular matrix mineralization were detected by ALP staining and alizarin red staining. Expression of mRNA from osteoblast-related genes such as collagen type I(COLL-I),osteocalcin(OCN), osteoprotegerin (OPG) and β-catenin was examined by RT-PCR method.RESULTS:Materials science experiments:doping of Li to CPC did not change the physical mechanical properties of cements,including setting time,pore size distribution,porosity,compressive strength,composition and morphology. Cells science experiments:SEM showed that MC3T3-E1 cells were well adhered and grown on the surface of the materials.Under fluorescent microscope,cells in Li/CPC group had more full cytoskeleton, actin relatively stretched.CCK-8 experiments showed Li/CPC promoted osteoblast proliferation.ALP activity, ALP staining and alizarin red staining showed that Li/CPC promoted osteoblast differentiation and mineralization.Results of genetic test showed that Li/CPC promoted expression of osteoblast osteoblast-related genes.CONCLUSIONS: Li/CPC maintains good physical and chemical properties, with well biological activity and osteoconductivity.Li/CPC can promote the proliferation and differentiation of bone cells with certain Osteogenic activity.Doping GSK-3β (Glycogen synthase kinase-3β) inhibitor LiCl to CPC may be a new direction of bone tissue engineering study.