In Vitro Biocompatibility of SiCHA Nanopowders on Human Mesenchymal Stem Cells

Synthetic hydroxyapatite (HA) possesses good biocompatibility, bioactivity and osteoconductivity and closely mimics the mineralised phase of human bone and teeth. However, for many years the clinical researchers worldwide have been aware that the mineral phase of bone is not solely HA but contains a number of substituents (e.g. CO_3, Si, Zn, Sr, Na and Mg). Among the substituents, carbonate is the major substitute ions which are present about 2–8 wt. % depending mainly on the individual age. The presence of approximately 1 wt. % Si is known to be essential in bone formation and calcification. Thus, the present study is aimed at developing a new biomaterial consisting both of these two biologically important cations into the HA structure by synthesising silicon carbonated HA (SiCHA) powders via nanoemulsion method, and to assess the in vitro biocompatibility of the as-synthesised powders in response to human Bone Marrow derived Mesenchymal Stem Cells (hMSCs). Both the carbonate and silicon ions were successfully substituted into the HA lattice. Powders with carbonate encouraged better cell activity in comparison to the carbonate-free powders. While, SiHA and SiCHA–1 as-synthesised powders with high amount of Si ( 1 wt. %) tend to kill some cells at the early stage of seeding and hinder cells activity afterwards. Among the tested powders, SiCHA–2 as-synthesised powders is chosen as the optimum composition as it exhibited the highest cell viability and proliferation besides having the closest amount of carbonate and Si ions to the bone mineral.