Study On The Effects Of Calcium Phosphate-based Cements On Functions Of Cells Involved In Osteogenesis

Calcium phosphate cement (CPC) is a mixture of several calcium phosphates, and is capable of self-setting under physiological condition to form hydroxyapatite (HA) which is similar in structure and composition to the component of human bone. CPC has been successfully used as bone substitutes for a wide range of clinical applications. However, recent studies indicated that the rate of CPC degradability was extremely slow and the CPC bioactivity was low, which limited wider clinical application of CPC.CPC with various Ca/P ratios (1.4,1.5,1.6, and 1.67) were synthesized in this study. Afterwards, the effects of various Ca/P ratios on CPC bioactivity was evaluated in vitro using murine osteoblast-like cell MC3T3-E1. And cell attachment, proliferation and differentiation on different CPC disks were investigated. The results demonstrated that CPCs with lower Ca/P ratios have good biocompatibility and bioactivity and can promote MC3T3-E1 cell attachment, proliferation and differentiation, in comparison with the CPC that has a Ca/P ratio of 1.67. Although in the late culture period, the CPC with a Ca/P ratio of 1.67 can greatly enhance MC3T3-E1 cell proliferation, the CPC with a Ca/P ratio of 1.4 can significantly upregulate MC3T3-E1 cell differentiation.In addition, the effects of calcium silicate/calcium phosphate cement (CS/CPC) on the cell response of MC3T3-E1 and HUVEC (human umbilical vein endothelial cell) were also investigated. The results indicated that CS/CPC exhibited good biocompatibility to the osteoblast-like cells, and it induced better cell adhesion and cell spread. Simultaneously, cell proliferation and ALP activity of osteoblasts on the CS/CPC disks were significantly enhanced, and NO production in cells on the CS/CPC disks greatly increased. Additionally, on CS/CPC disks, HUVEC attached well on day 1 and cell proliferation was also greatly enhanced by day 7. In conclusion, these results suggest that the introduction of calcium silicate may improve the cell response involved in the osteogenesis and thus may be beneficial to further modify CPC as a better bone repairing material.