Initial in vitro interaction of osteoblasts with nano-porous alumina

In the present study we have used a characterised primary human cell culture model to investigate cellular interactions with nano-porous alumina. This material, prepared by anodisation, is being developed as a coating on titanium alloy implants. The structure of the alumina, as determined by X-ray diffraction and transmission electron microscopy, was amorphous. When studying cell/material interactions we used both biochemical and morphological parameters. Cell viability, proliferation and phenotype were assessed by measurement of redox reactions in the cells, cellular DNA, tritiated thymidine ([3H]-TdR) incorporation and alkaline phosphatase (ALP) production. Results showed a normal osteoblastic growth pattern with increasing cell numbers during the first 2 weeks. A peak in cell proliferation was seen on day 3, after which cell growth decreased, followed by an increase in ALP production, thus indicating that the osteoblastic phenotype was retained on the alumina. Cell adhesion was observed, the osteoblast-like cells having a flattened morphology with filipodia attached to the pores of the material. SDS-PAGE and western blot measurements showed that the nano-porous alumina was able to adsorb fibronectin. Trace amounts of aluminium ions were measured in the surrounding medium, but no adverse effect on cell activity was observed.