Effect Of Size And Concentration Of Hydroxyapatite Nanoparticles On Proliferation And Mineralization Of Odontoblast Cell MDPC-23

Background:Odontoblast is the only cell which can continuously produce dental hard tissues structure-dentin as so called reparative or secondary dentine in whole life. The hydroxyapatite is the basic inorganic units of the human bone and dental tissue. Nano-hydroxyapatite (nano-HAP) has its special biological properties, recent studies revealed that nano-HAP can promote proliferation and mineralization of osteoblast. However, there is no literature focused on its effect on the growth and mineralization of odontoblast cells.Objective:To evaluate the effects of different sizes and concentration of nano-HAP on proliferation and mineralization of odontoblast cell (MDPC-23).Methods:The size-controlled nano-HAP particles were prepared according to the theory of critical micelle concentration (CMC) as recently described. Fourier-transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM) were used for confirming the particle size morphology and chemical composition crystal purity. Nano-HAP particles with size of20(np20),40(np40), and70nm(np70) were placed into96-well plates which contained modified Eagle’s medium (DMEM, Gibco) containing10%fetal bovine serum (FBS, Gibco), each size with three different concentrations,20ug ml-1,50ug ml-1,100ug ml-1respectively. Therefore,9test groups and the control group without hydroxyapatite granules were assigned. The cell suspension was seeded at a density of5x103per well, with8replicates per group. The cultures were maintained in a humidified atmosphere with5%CO2at37℃, the cell number was evaluated using the MTT[3-(4,5-dimethyl-2-thyazolyl)-2,5-diphenyl-2H-tetrazolium-bromide]test after washing three times with PBS after seeding1,3,5,7days. At24h after seeding, images of cells were took using a transmission electron microscope and inverted microscope after cultured1,3,5,7days.Results:In group with np20and np70in cultured early can obviously promote the growth of the MDPC-23, promotion effect is not obvious late after5days, the np40significantly inhibited the growth of MDPC-23. Initial stage of incubation, the inhibition of cell growth is more obvious while nano-HAP concentration is higher, with the extension of culture time, inhibition is reduced, but the high concentrations inhibitory effect of np40was higher than that of low concentration. Metallogenic stimulative effect of different concentrations of various particle size of nano-HAP on MDPC-23is not obvious. Various scales of the nano-HAP were observed into the cell.Conclusion:Np20, nP70have no apparent stimulative effect on growth and mineralization of odontoblast cell MDPC-23, np40inhibits odontoblasts growth.