Titanium and titanium alloys are widely used in orthopedic implants. Modifying the nanotopography provides a new strategy to improve osseointegration of titanium substrates. Filamentous actin (F-actin) polymerization, as a mechanical loading structure, is generally considered to be involved in cell migration, endocytosis, cell division, and cell shape maintenance. Whether F-actin is involved and how it functions in nanotube-induced osteogenic differentiation of mesenchymal stem cells (MSCs) remain to be elucidated. In this study, we fabricated TiO₂ nanotubes on the surface of a titanium substrate by anodic oxidation and characterized their features by scanning electron microscopy (SEM), X-ray energy dispersive analysis (EDS), and atomic force microscopy (AFM). Alkaline phosphatase (ALP) staining, Western blotting, qRT-PCR, and immunofluorescence staining were performed to explore the osteogenic potential, the level of F-actin, and the expression of MKL1 and YAP/TAZ. Our results showed that the inner diameter and roughness of TiO₂ nanotubes increased with the increase of the anodic oxidation voltage from 30 to 70 V, while their height was 2 μm consistently. Further, the larger the tube diameter, the stronger the ability of TiO₂ nanotubes to promote osteogenic differentiation of MSCs. Inhibiting F-actin polymerization by Cyto D inhibited osteogenic differentiation of MSCs as well as the expression of proteins contained in focal adhesion complexes such as vinculin (VCL) and focal adhesion kinase (FAK). In contrast, after Jasp treatment, polymerization of F-actin enhanced the expression of RhoA and transcription factors YAP/TAZ. Based on these data, we concluded that TiO₂ nanotubes facilitated the osteogenic differentiation of MSCs, and this ability was enhanced with the increasing diameter of the nanotubes within a certain range (30–70 V). F-actin mediated this process through MKL1 and YAP/TAZ.

钛和钛合金广泛用于整形外科植入物中。修改纳米形貌为改善钛基底的骨整合提供了新的策略。丝状肌动蛋白（F-actin）聚合作为一种机械负载结构，通常被认为与细胞迁移，内吞作用，细胞分裂和细胞形状维持有关。F-肌动蛋白是否参与及其在纳米管诱导的间充质干细胞（MSCs）的成骨分化中的功能仍有待阐明。在这项研究中，我们制造了TiO ₂钛基体表面通过阳极氧化形成纳米管，并通过扫描电子显微镜（SEM），X射线能量色散分析（EDS）和原子力显微镜（AFM）表征其特征。进行了碱性磷酸酶（ALP）染色，Western印迹，qRT-PCR和免疫荧光染色以探讨成骨潜能，F-肌动蛋白水平以及MKL1和YAP / TAZ的表达。我们的结果表明，TiO ₂纳米管的内径和粗糙度随着阳极氧化电压从30 V增加到70 V而增加，而其高度始终为2μm。另外，管径越大，TiO ₂的能力越强。纳米管促进MSC的成骨分化。Cyto D抑制F-肌动蛋白的聚合反应可抑制MSC的成骨分化以及粘着斑复合物（如长春菊素（VCL）和粘着斑激酶（FAK））中所含蛋白质的表达。相反，在Jasp处理后，F-肌动蛋白的聚合增强了RhoA和转录因子YAP / TAZ的表达。根据这些数据，我们得出结论，TiO ₂纳米管促进了MSC的成骨分化，并且在一定范围内（30-70 V），随着纳米管直径的增加，这种能力得到了增强。F-肌动蛋白通过MKL1和YAP / TAZ介导这一过程。