Qazi Taimoor H, Tytgat Liesbeth, Dubruel Peter, Duda Georg N, Van Vlierberghe Sandra, Geissler Sven
Julius Wolff Institute for Biomechanics and Musculoskeletal Regeneration, Charité Universitätsmedizin Berlin, Augustenburger Platz 1, 13353 Berlin, Germany.
Berlin-Brandenburg Center for Regenerative Therapies, Charité Universitätsmedizin Berlin, Augustenburger Platz 1, 13353 Berlin, Germany.
ACS Biomater Sci Eng. 2019 Oct 14;5(10):5348-5358. doi: 10.1021/acsbiomaterials.9b00843. Epub 2019 Sep 26.
Cell encapsulation in confining 3D hydrogels typically prevents encapsulated cells from spreading and establishing cell-cell contacts. Interactions with neighboring cells or with the extracellular matrix (ECM) influence the paracrine activity of mesenchymal stromal cells (MSCs), but how these interactions are regulated by structural properties of biomaterial scaffolds remains insufficiently explored. Here, we describe the use of extrusion-based 3D printing to fabricate acellular, gelatin-based scaffolds with programmed strut spacings of 400 (small), 500 (medium), and 600 μm (large). These scaffolds showed similar effective Young's moduli in the range of 2-5 kPa, and varied based on average pore size which ranged from ∼200 μm (small pore: SP) through ∼302 μm (medium pore: MP) to ∼382 μm (large pore: LP). When seeded with MSCs, pore size guided cell distribution on the scaffolds, with smaller pores preventing cell infiltration, medium ones causing cells to aggregate in between struts, and large ones causing cells to flow through after attachment on the struts. These changes in cell distribution regulated cell-cell and cell-matrix interactions at the gene level, as assessed by pathway focused PCR arrays. Medium pore size scaffolds stimulated the highest paracrine secretion of a panel of angiogenic cytokines. This enhancement of paracrine activity substantially improved endothelial cell migration in a chemotaxis assay, increased single cell migration kinetics such as velocity, and stimulated the formation of robust tubular structures. Together, these findings not only provide new insights on cellular interactions in scaffold environments but also demonstrate how 3D biomaterial design can instruct and enhance the regenerative paracrine activities of MSCs.
将细胞包裹在具有限制作用的三维水凝胶中通常会阻止被包裹的细胞扩散并建立细胞间接触。与相邻细胞或细胞外基质（ECM）的相互作用会影响间充质基质细胞（MSC）的旁分泌活性，但生物材料支架的结构特性如何调节这些相互作用仍未得到充分探索。在此，我们描述了使用基于挤出的3D打印技术来制造无细胞的、明胶基支架，其设计的支柱间距为400（小）、500（中）和600μm（大）。这些支架在2 - 5 kPa范围内显示出相似的有效杨氏模量，并根据平均孔径而变化，平均孔径范围从约200μm（小孔径：SP）到约302μm（中等孔径：MP）再到约382μm（大孔径：LP）。当接种MSC时，孔径引导细胞在支架上的分布，较小的孔径阻止细胞浸润，中等孔径使细胞聚集在支柱之间，而大孔径使细胞在附着于支柱后流过。如通过通路聚焦PCR阵列所评估的，细胞分布的这些变化在基因水平上调节了细胞 - 细胞和细胞 - 基质相互作用。中等孔径的支架刺激了一组血管生成细胞因子的最高旁分泌分泌。旁分泌活性的这种增强在趋化性测定中显著改善了内皮细胞迁移，增加了单细胞迁移动力学（如速度），并刺激了坚固管状结构的形成。总之，这些发现不仅为支架环境中的细胞相互作用提供了新见解，还展示了3D生物材料设计如何指导和增强MSC的再生旁分泌活性。
