The role of temperature of sintering of tricalcium phosphate ceramic on the adhesion rate of human monocyte and monocyte derived macrophages

The objective of this study was to investigate the effect of temperature of sintering of tricalcium phosphate ceramic (TCP) on the adherence and viability of monocyte and monocyte derived macrophages. The monocytes were isolated from human peripheral blood, biotin labeled and seeded at a density of 5×10⁵ cells/well according to standard laboratory procedures. Cells were considered macrophages after remaining in culture for 24 hours. Cells were then plated in each microtiter well preloaded with TCP of different sintering temperatures (400, 800 and 1150°C). At the end of 1, 2, 3 and 7 days the viability and cell number of monocyte or monocyte derived macrophages were determined using an established assay (biotin-labeled-macrophages). Cell number was determined in control wells with known amounts of cell number, a standard curve was generated by plotting absorbance units versus cell number. At the end of each phase, the blocks were collected and prepared for SEM evaluation. The data from this experiment suggest that: (i) monocytes and macrophages are capable of surviving on all different types of blocks tested over a 7 day period, (ii) SEM evaluation of the ceramic blocks showed an increase in the size and number of micro and macropores with time in blocks sintered at 400 and 800°C. In contrast, the size and number of pores calculated from representative views of TCP blocks sintered at 1150°C were significantly lower than the other two groups. The mechanism of action of these cells toward the aforementioned bioceramic surfaces has to be investigated in a larger scale. Information obtained from this study provided new insights on the interrelationship between bioceramics, temperature of sintering effect, incubation time and the possible cell response during chronic inflammation at the site of implantation