Effect of Polydopamine-Coated Strontium-Doped Hydroxyapatite Nanowires on Bone Marrow Mesenchymal Stem Cells and Umbilical Vein Endothelial Cells.

Hydroxyapatite nanowires (HAW) can effectively improve the bone repair ability in bone engineered tissue. However, due to their single function, the application of HAWs in biological tissue engineering materials is limited. In this study, strontium-doped hydroxyapatite nanowires (SrHAW) were synthesized by a hydrothermal method and coated with polydopamine (PDA) to improve the function of HAWs. The material structure, biocompatibility evaluation, and differentiation capability testing of PDA-coated strontium-doped hydroxyapatite (SrHAW@PDA) nanowires were conducted. Then, the nanowires were co-cultured with rat bone marrow mesenchymal stem cells (BMSCs) and rat umbilical vein endothelial cells (UVECs) to prepare cell spheroids. Compared with the undoped and uncoated HAW, the SrHAW@PDA nanowires enhanced the cell activity and their angiogenesis and osteogenesis abilities. In addition, their performance in the three-dimensional spheroid also played a positive role in the cells in the spheroid. Due to the presence of PDA, the adhesion between the cells in the three-dimensional spheroid and the nanowires were enhanced. In summary, these results show that SrHAW@PDA has the potential to be used as an alternative material to regulate cell biological activity in three-dimensional cell spheroids.