In comparison to synthetic hydrogels where ligand density and stiffness can be independently tuned, cell responses are expected to deviate on native biopolymer networks where ligand density and stiffness are coupled. Here we probe the tensional homeostasis of fibroblasts on methacrylated gelatin (GelMA) gels, which are widely used in tissue engineering applications. On 5%–15% GelMA gels which are very soft (10–100’s of Pa’s in stiffness), fibroblasts were found to spread extensively and assemble prominent stress fibers and focal adhesions. Probing of contractile mechanics using trypsin-induced detachment revealed adhesive drag, but not contractility, was sensitive to GelMA concentration. Contractility-altering drugs blebbistatin and nocodazole, which exhibited opposite effects on focal adhesion size, both led to reduction in adhesive drag and cell rounding. However, cell motility was impacted only in nocodazole-treated cells. Collectively, our experiments suggest that on soft GelMA gels, contractility-independent adhesion clustering mediated by high ligand density can drive cell spreading and motility.

与可以独立调节配体密度和刚度的合成水凝胶相比，细胞反应预计会偏离配体密度和刚度耦合的天然生物聚合物网络。在这里，我们探讨了广泛用于组织工程应用的甲基丙烯酸化明胶 (GelMA) 凝胶上成纤维细胞的张力稳态。在非常柔软的 5%–15% GelMA 凝胶上（硬度为 10–100 Pa's），发现成纤维细胞广泛扩散并聚集显着的应力纤维和粘着斑。使用胰蛋白酶诱导的分离对收缩力学的探测揭示了粘附阻力，但不是收缩性，对 GelMA 浓度敏感。改变收缩力的药物 blebbistatin 和 nocodazole，它们对粘着斑大小表现出相反的影响，两者都导致粘合剂阻力和细胞变圆的减少。然而，细胞运动仅在诺考达唑处理的细胞中受到影响。总的来说，我们的实验表明，在软 GelMA 凝胶上，由高配体密度介导的不依赖收缩性的粘附聚集可以驱动细胞扩散和运动。