Tetracalcium phosphate and biphasic tetracalcium phosphate/tricalcium phosphate powders' effects evaluation on human osteoblasts

Background: Calcium ions levels in bone niches have been demonstrated to severely influence new bone formation. Osteoinductive scaffolds containing calcium have been largely studied to control the release of calcium in bone regeneration and tissue engineering purpose. The aim of the present study was, firstly, to synthesize two different resorbable calcium phosphate-based powders, thought to be reservoirs of calcium ions, and secondary, to investigate their effects on human osteoblasts, in order to develop a suitable titanium coating material. Methods: Tetracalcium phosphate (A450) and biphasic tetracalcium phosphatae/tricalcium phosphate (A850) powders were prepared with an innovative method. The presence of calcium phosphate structures was chemically confirmed with XRD. Furthermore, powders macroscopic aspect was observed with a stereomicroscope. For in-vitro experiments, human osteoblastic cells were cultured in the presence of A450 and A850, and assayed for viability and metabolic activity through Crystal Violet and MTT, respectively. Results: Our synthesis led to the formation of calcium phosphates in both samples, even though A850 presented a higher level of crystallinity and a more powdery aspects than A450. Both the samples enhanced the viability of cultured cells, inhibiting cell metabolic activity in the case of A850, which furthermore showed to be internalized by cells. Conclusions: We developed two different kind of calcium phosphate-based powders and we tested their effect on human osteoblasts, underlying the possibility of use calcium phosphate-based coatings to enhance cell response on implantable materials.