Substrate affects the initial attachment and subsequent behavior of human osteoblastic cells (Saos-2)

Interaction between implant materials and bone cells contributes to the cli nical success of dental implants. The object of this study was to investiga te the initial attachment and subsequent behavior of human osteoblastic cel ls (Saos-2) to pure titanium (Ti), hydroxyapatite (HA), and glass. We, ther efore, performed a time-course study for examining the area, attachment rat e, distribution of focal adhesion kinase (FAK) vinculin, and actin, and the motility of Saos-2 cells on the materials. On Ti, cell area increased grad ually, whereas on HA, cells spread quickly, but quitted spreading at 12 h a fter cell seeding. The number of cells on HA was greater than on the other materials. On Ti, the numbers of FAK- and vinculin-positive focal adhesions increased continuously. On HA, although the number of FAK-positive focal a dhesions also increased continuously, the number of vinculin-positive focal adhesions decreased. Furthermore, actin staining showed that the cells on HA poorly formed stress fibers with weak polarity, whereas the cell on Ti p ossessed well-defined polarized stress fibers. On HA, cells started extensi on earlier than on Ti, motility was inactive, and the cells settled on the materials. These results suggest that the earlier settling of osteoblasts o n HA might result in earlier osteogenesis on HA than other materials. (C) 2 001 Published by Elsevier Science Ltd.