In this study, human mesenchymal stem cells (hMSCs) were cultured on the hydroxyapatite (HA) and mineralized collagen (MC), and their proliferation, adhesion and differentiation, especially the molecular mechanisms on gene level were investigated. Proliferation and morphological responses of hMSCs and their osteogenic differentiation were detected by quantitative detection of alkaline phosphatase. Gene expression profilings were examined by microarrays and the gene expressions data were studied through gene ontology terms and pathway analyses. The results showed that MC promoted cell proliferation and osteogenic differentiation of hMSCs. Microarray analysis showed that MC was conducive to express osteogenesis-related genes, such as BMP-2, COL1A1, CTSK, and stimulate osteogenic differentiation, like osteoblast differentiation pathway and skeletal system development pathway.

In this study, calcium carbonate (CaCO ₃ ) nanoparticles with spherical structure were regulated by arginine and successfully synthesized via a facile co-precipitation method. The average particle size of as-prepared CaCO ₃ was about 900 nm. The properties of nanostructured CaCO ₃ particles were characterized by scanning electron microscope, Fourier transform infrared spectroscopy, X-ray diffraction and size distribution. After modified with polyethyleneimine (PEI), the ability of PEI-CaCO ₃ nanoparticles to carry GFP-marked p53 gene (pEGFP-C1- p53 ) into cancer cells to express P53 protein were studied. Meanwhile, the cytotoxicity, transfection efficiency, cells growth inhibition and the ability to induce apoptosis by expressed P53 protein were conducted to evaluate the performances of PEI-CaCO ₃ nanoparticles. The results show that prepared PEI-CaCO ₃ nanoparticles had good biocompatibility and low cytotoxicity in a certain concentration range. PEI-CaCO ₃ effectively transfected pEGFP-C1 gene into epithelial-like cancer cells. And with the expression of GFP-P53 fusion protein, pEGFP-C1- p53- gene-loaded PEI-CaCO ₃ particles significantly reduced the proliferation of cancer cells. These findings indicate that our PEI-modified CaCO ₃ nanoparticles are potential to be successfully used as carriers for gene therapy.

Calcium carbonate, especially with nanostructure, has been considered as a good candidate material for bone regeneration due to its excellent biodegradability and osteoconductivity. In this study, rod-like calcium carbonate nanoparticles (Rod-CC NPs) with desired water dispersibility were achieved with the regulation of poly (acrylic acid). Characterization results revealed that the Rod-CC NPs had an average length of 240 nm, a width of 90 nm with an average aspect ratio of 2.60 and a negative ζ-potential of −22.25 ± 0.35 mV. The degradation study illustrated the nanoparticles degraded 23% at pH 7.4 and 45% at pH 5.6 in phosphate-buffered saline (PBS) solution within three months. When cultured with MC3T3-E1 cells, the Rod-CC NPs exhibited a positive effect on the proliferation of osteoblast cells. Alkaline phosphatase (ALP) activity assays together with the osteocalcin (OCN) and bone sialoprotein (BSP) expression observations demonstrated the nanoparticles could induce the differentiation of MC3T3-E1 cells. Our study developed well-dispersed rod-like calcium carbonate nanoparticles which have great potential to be used in bone regeneration.