Nano Calcium Phosphate Is Associated With Bone Tissue Cell Interactions

With the development of nanotechnology, nanomaterials show a huge potential in thebiomedical field. Calcium phosphate (CP), the major inorganic component of sclerous tissues,has been widely used in the replacer, filler and drug/DNA carrier for bone due to its excellentbiocompatibility, biodegradability and osteoconduction. But application of nano CP in clinic islimited due to its ambiguous toxicity and lacking knowledge of interaction betweennanoparticles and cell.In this study, CP was researched from three points of view as follows: first, three kinds of CPnanoparticles were synthesized by hydro-thermal method and chemical precipitation method.Their morphologies were spherical, rod-like and fusiform, respectively. These samples werecharacterized by transmission electron microscope (TEM), field emission scanning electronmicroscopy (FESEM), Atomic force microscopy (AFM), dynamic light scattering (DLS) andX-ray diffraction (XRD). Second, three kinds of CP nanoparticles with different shapes wereused to investigate effects of morphology on the biological behavior of MG-63cells, includingadhesion, proliferation, differentiation, migration and apoptosis of cells. In addition, thetransmembrane transport process of CP nanoparticles into the MG-63cells was further studied.Three kinds of CP nanoparticles were labeled by rhodamine and co-cultured with MG-63cell fora period of time, then were observed by confocal microscopy to understand how CPnanoparitcles move into MG-63. Chlorpromazine, nystatin, wortmannin and dynasore were usedto blocking-up four uptake pathways, including Clathrin-mediated endocytosis,Caveolae-mediated endocytosis, macropinocytosis. The dynasore is an inhibitor of dynamin.MG-63was treated with every inhibitor and co-cultured with CP nanoparitcles, and uptake of CPnanoparticles by cells was observed using confocal microscopy. The main results andconclusions obtained are as follows:1) Rod-like, spherical and fusiform CP nanoparticles were successfully prepared, which ofthem had a size of120nm,50nm and120nm respectively. Rod-like nanoparticles held a highdegree of crystallinity, fusiform nanoparticle had a lower one yet the spherical nanoparticleexisted in an amorphous form. These three kinds of particles were filmed on the glass and theroughness of the films was evaluated. Result showed that the film of spherical nanoparticle had a higher roughness and the roughness of other two films was similar to each other and muchsmaller than the spherical one.2) The morphology and crystallinity of these CP nanoparticles had significant influence onthe proliferation of MG-63cells. CP with higher length-diameter ratio and crystallinity wouldpromote the proliferation of cells. And the roughness of CP films had an obvious impact on theadhesion process of cells. The inhibitory action aggravated with the increase of roughness offilms. All these three kinds of CP nanoparticles could promote the cell migration effectively andhad little effect on the differentiation and apoptosis of cells.3) The uptake of CP into the cells was a process of active transportation and the energywas necessary in the process. Chlorpromazine and nystatin had little effect on the endocytosis ofCP nanoparticles. Nevertheless, wortmannin could well restrain the endocytosis of CP. Thisindicated that the CP nanoparticles most probably moved into cells through themacropinocytosis.