Osteoblast-like MG-63 cell growth on fluorapatite (FA) surfaces

There is increasing demand for biomedical implants to correct skeletal defects caused by trauma, disease or genetic disorder. Objectives: In this study, the MG-63 cells are grown on implants coated with organized and disorganized FA surfaces to study the biocompatibility, initial cellular response and the underlying mechanisms during this process. Methods: The cells were subcultured in 10% FBS MEM for 3-21 days on the two surfaces. Specimens were observed under SEM, counted, examined by flow cytometry and analyzed using the human pathway-focused matrix and adhesion PCR array. Results: After 3 days, the cell number on organized FA surface was significantly higher than on the disorganized surface. The two surfaces showed excellent biocompatibility and no apoptosis occurred on either surface. Of the 84 focused pathway genes, a total of 15 genes were either up or down regulated in the cells on organized FA surface compared to the disorganized surface. Of the cell adhesion molecules, the up-regulation of versican (VCAN), hyaluronan synthase 1 (HAS1), integrin alpha M (ITGAM), and selectin L (SELL) was coordinated with the down-regulation of integrin alpha 7 and 8 (ITGA 7 and 8), laminin alpha 2 (LAMA2), catenin delta 2 (CTNND2), and platelet/endothelial cell adhesion molecule (PECAM1). Among the ECM proteases, the up-regulation of the matrix metalloproteinases 10 and 13 (MMP 10 and 13) and ADAM metallopeptidase with thrombospondin type 1 motif, 8 (ADAMTS 8) corresponded with the down-regulation of 3 other metallopeptidases. Conclusion: The enhanced cellular response of MG-63 cells to the organized FA crystal surface was closely related to the favorable micro-environment involving delicately regulated matrix and adhesion molecules. The long term effects of this novel crystal surface on the cell differentiation and mineralization need to be studied further. This study was supported by NIH grants DE015599.