Calcium Carbonate/Hydroxyapatite Microparticles and Osteoblast Responses

Calcium carbonate (CC)-hydroxyapatite (HAP) porous microparticles have gained a lot of popularity as a promising material for clinical applications. The objective of this study is to evaluate the effects of CC-HAP microparticles on osteoblast-like cells to be used as a bone-regeneration biomaterial. In this study, the different concentrations of conditioned media were used to compare the effects of released ions from CC-HAP microparticles. The material’s characteristics demonstrated that the immersion in cell culture medium did not change the crystal phases of CC-HAP. The decrease of calcium ions in cell culture medium is due to the dissolution-precipitation reactions on the material surfaces, which made more crystalline surfaces. The atomic absorption spectroscopy measurement demonstrated that the dissolution-precipitation reactions on the material surfaces in cell culture medium happened in 3 days and were stable between 3 to 5 days. The conditioned media immersed in cell culture medium for 4 days were used for further experiments. Cell evaluations demonstrated that excessive adding of CC -HAP could inhibit cell behaviors such as cell adhesion, proliferation, and differentiation. The cell adhesion indicated by the number of vinculin-positive focal adhesions per cell decreased with the increase of the CC-HAP concentrations. The cells cultured with CC-HAP proliferated at a lower rate than the control without CC-HAP. One of the reasons for the inhibition of cell proliferation was thought to be less formation of focal adhesions with higher concentrations of CC-HAP. The excessive adding of CC-HAP had an inhibitory effect on osteoblast differentiation. The results of this study revealed that the conditioned media prepared by immersion of CC-HAP porous microparticles in cell culture media had effects on the behaviors of osteoblast-like cells such as cell adhesion, proliferation, and differentiation.