Specific toxicity of calcium phosphate bions for human venous and arterial endothelial cells

Abstract

Aim. To compare toxicity of calcium phosphate bions (CPB) and magnesium phosphate bions (MPB) for endothelial cells. Methods. To assess endothelial toxicity of the bions, we first added equal concentrations of either MPB or CPB to: 1) non-confluent or confluent cultures of immortalized human venous endothelial cells EA.hy 926 with the exposure time of 24 h or 4 h, respectively; 2) confluent cultures of commercially available primary human coronary artery and internal thoracic artery endothelial cells, with the exposure time of 24 h. Endothelial toxicity was then evaluated by combined Hoechst 33342 and ethidium bromide staining following fluorescence microscopy and by colorimetric cytotoxicity assay. In addition, we attempted to determine the pathway of bion-induced cell death utilizing flow cytometry. Results. In contrast to the MPB, CPB induced apoptosis of all studied endothelial cell lines. Resistance of endothelial cells to the CPB was defined by their confluence (confluent cultures demonstrated higher resistance), and cell type (internal thoracic artery endothelial cells were more resistant to the CPB as compared to the coronary artery endothelial cells). Conclusions. Endothelial toxicity of the CPB is defined by their specific mineral composition but not by their corpuscular nature, which is common for all nanoparticles. Addition of the CPB to the confluent cultures of primary human arterial cells and to immortalized human venous endothelial cells evoked their death. On the contrary, exposure to the MPB did not cause any toxic effects. Human internal thoracic artery endothelial cells are more resistant to the CPB in comparison with coronary artery endothelial cells.