Selenium-Substituted Hydroxyapatite Nanoparticles and their in Vitro Interaction on Human Bone Marrow- and Umbilical Cord-Derived Mesenchymal Stem Cells

Hydroxyapatite (HA) is biocompatible with high binding activity to DNA and protein. Selenium (Se) plays a specific role in human health. Incorporation of selenium into biocompatible hydroxyapatite (HA) may endow the material with novel characteristics. in this work, a series of nano-hydroxyapatite [SeHA] powders with 1 to 5 mass-% substituted selenium were synthesised by an aqueous precipitation method using sodium selenite. The precipitates were dried at 60°C and their dried ground powders were characterised by XRD, FTIR end TEM. Substitution of Se ions took place in the crystal lattice of HA. The presence of Na ions in the hydroxyapatite was detected by XRF in all samples with selenium substituted in the lattice. No change was detected in the morphology of the rod-shaped particles, but a reduction in their size was observed as the selenium content increased. The cytotoxicity of the powders on human bone marrow mesynchymal stem cells (BM-MSCs) and umbilical cord-derived mesenchymal stem cells (UC-MSCs) was evaluated in vitro. The amount of 0.59 mM Se, corresponding to 2 mass-% substitution in the HA lsttice, did not show cytotoxicity and stimulated proliferation of UC-MSCs in contrast to pure HA powders which inhibited growth of cells. Toxicity started to appear in samples when substitution exceeded 2 mass-%. The highest concentration (5 mass-%) was severely cytotoxic. The results suggest that selenium substitution might be an attractive cell delivery modification of hydroxyapatite nanoparticles for future use in tissue engineering.