Osteoblast differentiation with titania and titania-silica-coated titanium fiber meshes.
ABSTRACT Two surface-reactive sol-gel coatings, namely titania (TiO2) and a mixture of titania and silica (TiSi), were applied to titanium fiber meshes. Differentiation of rat bone marrow stromal cells toward an osteogenic phenotype with coated and uncoated (cpTi) substrates was compared. The amount of DNA in cpTi and TiSi matrices did not increase after day 3, but with TiO2 matrices the amount increased for 7 days. The prolonged period of proliferation with TiO2 scaffolds resulted in a delay in alkaline phosphatase induction. However, osteocalcin incorporation into extracellular matrix by day 14 was greater with TiO2 scaffolds than with cpTi scaffolds. Calcium deposition was also greater with TiO2-coated substrates than with uncoated substrates. With the TiSi scaffolds osteocalcin production and mineralization were lower than with the cpTi scaffolds. The current study confirms our previous findings that titanium fiber mesh supports attachment, growth, and differentiation of rat bone marrow stromal cells. Furthermore, the osteogenic capacities of cell-scaffold constructs under cell culture conditions were increased with a sol-gel-derived titania coating, but not with a titania-silica coating.
Article: Porous titanium scaffolds fabricated using a rapid prototyping and powder metallurgy technique.[show abstract] [hide abstract]
ABSTRACT: One of the main issues in orthopaedic implant design is the fabrication of scaffolds that closely mimic the biomechanical properties of the surrounding bone. This research reports on a multi-stage rapid prototyping technique that was successfully developed to produce porous titanium scaffolds with fully interconnected pore networks and reproducible porosity and pore size. The scaffolds' porous characteristics were governed by a sacrificial wax template, fabricated using a commercial 3D-printer. Powder metallurgy processes were employed to generate the titanium scaffolds by filling around the wax template with titanium slurry. In the attempt to optimise the powder metallurgy technique, variations in slurry concentration, compaction pressure and sintering temperature were investigated. By altering the wax design template, pore sizes ranging from 200 to 400 microm were achieved. Scaffolds with porosities of 66.8 +/- 3.6% revealed compression strengths of 104.4+/-22.5 MPa in the axial direction and 23.5 +/- 9.6 MPa in the transverse direction demonstrating their anisotropic nature. Scaffold topography was characterised using scanning electron microscopy and microcomputed tomography. Three-dimensional reconstruction enabled the main architectural parameters such as pore size, interconnecting porosity, level of anisotropy and level of structural disorder to be determined. The titanium scaffolds were compared to their intended designs, as governed by their sacrificial wax templates. Although discrepancies in architectural parameters existed between the intended and the actual scaffolds, overall the results indicate that the porous titanium scaffolds have the properties to be potentially employed in orthopaedic applications.Biomaterials 10/2008; 29(27):3625-35. · 7.40 Impact Factor