Bone/cartilage interfacial tissue engineering needs to satisfy the differential properties and architectures of the osteochondral region. Therefore, biphasic or multiphasic scaffolds that aim to mimic the gradient hierarchy are widely used. Here, we find that two differently structured (topographically) three-dimensional scaffolds, namely, "dense" and "nanofibrous" surfaces, show differential stimulation in osteo- and chondro-responses of cells. While the nanofibrous scaffolds accelerate the osteogenesis of mesenchymal stem cells, the dense scaffolds are better in preserving the phenotypes of chondrocytes. Two types of porous scaffolds, generated by a salt-leaching method combined with a phase-separation process using the poly(lactic acid) composition, had a similar level of porosity (~90%) and pore size (~150 μm). The major difference in the surface nanostructure led to substantial changes in the surface area and water hydrophilicity (nanofibrous ≫ dense); as a result, the nanofibrous scaffolds increased the cell-to-matrix adhesion of mesenchymal stem cells significantly while decreasing the cell-to-cell contracts. Importantly, the chondrocytes, when cultured on nanofibrous scaffolds, were prone to lose their phenotype, including reduced chondrogenic expressions (SOX-9, collagen type II, and Aggrecan) and glycosaminoglycan content, which was ascribed to the enhanced cell-matrix adhesion with reduced cell-cell contacts. On the contrary, the osteogenesis of mesenchymal stem cells was significantly accelerated by the improved cell-to-matrix adhesion, as evidenced in the enhanced osteogenic expressions (RUNX2, bone sialoprotein, and osteopontin) and cellular mineralization. Based on these findings, we consider that the dense scaffold is preferentially used for the chondral-part, whereas the nanofibrous structure is suitable for osteo-part, to provide an optimal biphasic matrix environment for osteochondral tissue engineering.

中文翻译：

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具有不同拓扑表面的三维多孔支架中的差异软骨和骨刺激为双相骨软骨工程提供了设计策略。

骨/软骨界面组织工程需要满足骨软骨区域的差异特性和结构。因此，旨在模拟梯度层次结构的双相或多相支架被广泛使用。在这里，我们发现两种不同结构（拓扑）的三维支架，即“致密”和“纳米纤维”表面，在细胞的骨和软骨反应中表现出不同的刺激。虽然纳米纤维支架加速间充质干细胞的成骨，但致密支架可以更好地保留软骨细胞的表型。通过盐浸法结合聚乳酸组合物的相分离过程生成的两种类型的多孔支架具有相似水平的孔隙率（~90%）和孔径（~150μm）。表面纳米结构的主要差异导致表面积和水亲水性发生实质性变化（纳米纤维≫致密）；结果，纳米纤维支架显着增加了间充质干细胞的细胞与基质的粘附，同时减少了细胞与细胞的收缩。重要的是，当在纳米纤维支架上培养时，软骨细胞很容易失去其表型，包括软骨形成表达（SOX-9、II型胶原和聚集蛋白聚糖）和糖胺聚糖含量减少，这归因于细胞与基质粘附力的增强和细胞基质粘附力的降低。细胞与细胞的接触。相反，间充质干细胞的成骨通过细胞与基质粘附力的改善而显着加速，如成骨表达（RUNX2、骨唾液蛋白和骨桥蛋白）和细胞矿化的增强所证明。基于这些发现，我们认为致密支架优先用于软骨部分，而纳米纤维结构适合骨部分，为骨软骨组织工程提供最佳的双相基质环境。