Institute for Bioengineering of Catalonia (IBEC), The Barcelona Institute of Science and Technology (BIST), c/Baldiri Reixac 10-12, E-08028, Barcelona, Spain.
Biofabrication. 2020 Mar 4;12(2):025023. doi: 10.1088/1758-5090/ab7552.
The stiffness and topography of a cell's extracellular matrix (ECM) are physical cues that play a key role in regulating processes that determine cellular fate and function. While substrate stiffness can dictate cell differentiation lineage, migration, and self-organization, topographical features can change the cell's differentiation profile or migration ability. Although both physical cues are present and intrinsic to the native tissues in vivo, in vitro studies have been hampered by the lack of technological set-ups that would be compatible with cell culture and characterization. In vitro studies therefore either focused on screening stiffness effects in cells cultured on flat substrates or on determining topography effects in cells cultured onto hard materials. Here, we present a reliable, microfabrication method to obtain well defined topographical structures of micrometer size (5-10 μm) on soft polyacrylamide hydrogels with tunable mechanical stiffness (3-145 kPa) that closely mimic the in vivo situation. Topographically microstructured polyacrylamide hydrogels are polymerized by capillary force lithography using flexible materials as molds. The topographical microstructures are resistant to swelling, can be conformally functionalized by ECM proteins and sustain the growth of cell lines (fibroblasts and myoblasts) and primary cells (mouse intestinal epithelial cells). Our method can independently control stiffness and topography, which allows to individually assess the contribution of each physical cue to cell response or to explore potential synergistic effects. We anticipate that our fabrication method will be of great utility in tissue engineering and biophysics, especially for applications where the use of complex in vivo-like environments is of paramount importance.
细胞外基质（ECM）的刚性和形貌是物理线索，在调节决定细胞命运和功能的过程中起着关键作用。虽然基质刚性可以决定细胞分化谱系、迁移和自组织，但形貌特征可以改变细胞的分化特征或迁移能力。尽管这两种物理线索在体内天然组织中都存在且固有，但体外研究受到缺乏与细胞培养和表征兼容的技术设备的阻碍。因此，体外研究要么集中在筛选在平板基质上培养的细胞的刚性效应上，要么集中在确定在硬质材料上培养的细胞的形貌效应上。在这里，我们提出了一种可靠的微加工方法，可在具有可调机械刚度（3-145kPa）的软聚丙烯酰胺水凝胶上获得具有微米级尺寸（5-10μm）的明确定义的形貌结构，该结构非常类似于体内情况。通过使用柔性材料作为模具的毛细作用力光刻法聚合具有形貌的聚丙烯酰胺水凝胶。形貌微结构可抵抗溶胀，可以通过 ECM 蛋白进行共形功能化，并维持细胞系（成纤维细胞和肌母细胞）和原代细胞（小鼠肠上皮细胞）的生长。我们的方法可以独立控制刚性和形貌，这允许单独评估每个物理线索对细胞反应的贡献，或探索潜在的协同效应。我们预计我们的制造方法将在组织工程和生物物理学中具有很大的实用性，特别是在需要使用复杂的类似体内环境的应用中。
