Effect of Microarc Oxidation-Treated Ti6Al4V Scaffold Following Low-Intensity Pulsed Ultrasound Stimulation on Osteogenic Cells in Vitro

The porous Ti6Al4V alloy has emerged to solve the biomechanical mismatch between implant and bone as its tunable mechanical properties. Cell-surface interaction is related to numerous factors—the surface’s chemical composition, morphological structure, and external effect. The microarc oxidation (MAO) method was employed in this study to improve the surface properties of scaffolds produced by Electron Beam Melting (EBM), and low-intensity pulse ultrasound (LIPUS) provides physical stimulation for cells in vitro. Although MAO-treated and untreated scaffolds shared the same three-dimensional (3D) structures, the former recreated a more affinity surface than the latter in the 3D room, which could stimulate cell adhesion, proliferation, and differentiation. Therefore, MG63 cells were represented with a stereoscopic cytoskeleton structure on the MAO-treated scaffold as numerous cellular filopodia/lamellipodia with rich extracellular matrix secretion, while flat and sheetlike cells were observed on the untreated scaffold. The expression of ALP, OCN, BMP2, Bmpr1a, and Runx2 were up-regulated by the MAO-treated scaffold; in addition, LIPUS stimulation effectively promoted cell proliferation and osteogenesis differentiation. In the future, the EBM–MAO strategy can be applied to prepare 3D hierarchical macro-/microstructure titanium implants for bone grafts, and LIPUS stimulation can be used as a therapeutic method simultaneously.