Rapid prototyped porous titanium coated with calcium phosphate as a scaffold for bone tissue engineering

High strength porous scaffolds and mesenchymal stem cells are required for bone tissue engineering applications. Porous titanium scaffolds (TiS) with a regular array of interconnected pores of 1000 microm in diameter and a porosity of 50% were produced using a rapid prototyping technique. A calcium phosphate (CaP) coating was applied to these titanium (Ti) scaffolds with an electrodeposition method. Raman spectroscopy and energy dispersive X-ray analysis showed that the coating consisted of carbonated hydroxyapatite. Cross-sectioned observations by scanning electron microscopy indicated that the coating evenly covered the entire structure with a thickness of approximately 25 microm. The bonding strength of the coating to the substrate was evaluated to be around 25 MPa. Rat bone marrow cells (RBMC) were seeded and cultured on the Ti scaffolds with or without coating. The Alamar Blue assay provided a low initial cell attachment (40%) and cell numbers were similar on both the uncoated and coated Ti scaffolds after 3 days. The Ti scaffolds were subsequently implanted subcutaneously for 4 weeks in syngenic rats. Histology revealed the presence of a mineralized collagen tissue in contact with the implants, but no bone formation. This study demonstrated that porous Ti scaffolds with high strength and defined geometry may be evenly coated with CaP layers and cultured mesenchymal stem cells for bone tissue engineering.