Shape of calcium phosphate bions defines a proatherosclerotic shift in cytokine secretion profile of endothelial cells

Study aim. To investigate whether the shape of calcium phosphate bions (CPB) affects their endothelial toxicity via evaluating the cytokine secretion profile of endothelial cells upon the exposure to either spherical or spindle-shaped CPB. Material and methods. For the experiments, we used an immortalized human vein endothelial cell line EA.hy 926. Cells were seeded into 6-well plates (3*105 cells) with the further: 1) addition of 100 |jL either spherical CPB, spindle-shaped CPB, or 1x phosphate buffered saline (PBS) upon 1 h following culture for 24 h (non-confluent cell culture); 2) culture for 44 h and subsequent addition of 100 jL either spherical CPB, spindle-shaped CPB, or PBS following culture for 4 h (confluent cell culture). Upon the collection of cell culture supernatant (n=11 wells per group), the levels of proatherosclerotic cytokines (interleukin (IL)-1ß, IL-6, IL-8, IL-10, IL-12, IL-23, tumor necrosis factor (TNF)-a, interferon (IFN)-y, and soluble vascular cell adhesion molecule (sVCAM)-1) were measured utilizing an enzyme-linked immunosorbent assay. Results. In a non-confluent cell culture, exposure to spindleshaped CPB increased the secretion of several proatherosclerotic cytokines (IL-1 ß, IL-10, IL-12, IL-23, IFN-y) compared to either spherical CPB-treated or control cells. In a confluent cell culture, exposure to either of CPB types decreased the release of IL-1 ß, IL- 10, and IFN-y; however, their concentration was still higher upon the exposure to spindle-shaped CPB in comparison with exposure to spherical CPB. Discriminant analysis and principal component analysis demonstrated that the cytokine secretion profile of spindle-shaped CPB-treated endothelial cells significantly differed from those of either spherical CPB-treated or control cells. Conclusion. Spindle-shaped CPB induce the secretion of proatherosclerotic cytokines by endothelial cells compared to spherical CPB; this suggests higher endothelial toxicity of spindleshaped CPB.