Initial interaction of rat bone marrow cells with non-coated and calcium phosphate coated titanium substrates

Initial interactions of rat bone marrow (RBM) cells with smooth titanium, rough titanium or calcium phosphate coated substrates were tested. Cells were seeded onto the substrates, and attachment, integrin expression and spreading and morphology were studied. We found no difference in attachment of RBM cells to the different materials. We did find differences in the percentage of attached cells within a certain time between replicate runs of the experiments. RBM cells on all materials express alpha1, alpha3, alpha5, alpha6 and beta1 subunits. Again there was a large difference in expression patterns on RBM cells in different runs. No difference was found in expression on the various materials. For alpha1, alpha5, alpha6 and beta1, no difference was found in expression between attached and unattached cells. Expression of alpha3 was similar on attached and unattached cells during early culture. At the end of culture, alpha3 expression was downregulated for attached cells and not for unattached cells. This resulted in a higher expression of alpha3 for unattached cells compared to attached cells. Cells did spread on all materials, and reached a larger cell size on smooth titanium than on the rough materials. Morphology of the cells on the materials differed. On smooth titanium, cells usually showed a compact cell body with short cellular extensions. On the rough materials, cells often showed elongated shapes, with many thin cellular extensions. From this we conclude that the substrate surface characteristics of the materials we used do not influence attachment or integrin expression during the initial cell-material interactions. On the other hand, spreading behavior and cell morphology do depend on substrate surface characteristics.