Cobalt content modulates characteristics and osteogenic properties of cobalt-containing hydroxyapatite in in-vitro milieu

Abstract To develop an efficient scaffold for bone tissue engineering application, the influence of cobalt ion as generator of a hypoxia-like response was examined on cobalt-containing hydroxyapatite (Co-HA) scaffold properties and cultured osteoblast-like cell behavior. FTIR and XRD spectra, as well as EDX analysis and elemental mapping, showed successful cobalt doping as well as the formation of cobalt-based compounds on the surface of HA particles. Metabolic activities of cultured MG-63 cells in the presence of the Co-HA scaffold also showed a fluctuation with increasing cobalt content and revealed maximum osteoblastic cell activity accompanied by a considerable apoptotic cell reduction when the cobalt content in HA reached to 1.25 % (LCo-HA). The results showed the cobalt content of more than 1.25 % in the Co-HA scaffold which results the cobalt concentrations of more than 12 ppm in culture medium may cause cytotoxic effect on osteoblastic metabolic activities on the scaffold. The apatite growth was also observed on the LCo-HA scaffold in simulated body fluid. Alkaline phosphatase activity and calcium deposition of the osteoblastic cells cultured on the LCo-HA scaffold also coincided with the results of characterization and cytotoxicity as compared to the HA scaffold and control sample. The results demonstrated that cobalt improves osteogenic properties of HA-based scaffolds, and the LCo-HA derivative with 1.25 % cobalt content can be considered as a potential cobalt-containing HA scaffold for use in bone tissue engineering.