Osteoblast attachment and mineralized nodule formation on rough and smooth 45S5 bioactive glass monoliths

Human primary osteoblast responses to smooth and roughened bioactive glass of 45S5 (Bioglass trade mark ) composition (46.1% SiO(2), 26.9% CaO, 2.6% P(2)O(5), 24.4% Na(2)O) were analysed in vitro. The smooth and rough surfaces had R(a) values and peak to valley distances of 0.04, 4.397, 2.027, and 21.328 microm, respectively. Cell attachment and morphology was observed using phalloidin staining of the actin cytoskeleton and revealed significant differences between smooth and rough surfaces. Cells that were spiky in appearance on the rough compared to the smooth surface formed an organized actin matrix much later on the rough surface. Scanning electron microscopy revealed many cell filipodia extending from more rounded cell bodies on the rough surface. A significantly greater number of nodules on the rough surface was observed, and these were shown to mineralize when supplemented with beta-glycerophosphate and dexamethasone. Raman spectroscopy confirmed the presence of hydroxyapatite in the mineralized cultures showing a definite peak at 964 cm(-1). FTIR analysis showed hydroxyapatite formation occurred more rapidly on the rough surface. This study demonstrates that although initial cell morphology was less advanced on the roughened surface, the cells were able to form mineralized nodules in greater numbers. This may have implications to bone tissue engineering using bioactive glasses.