Department of Biosciences and Bioengineering, Indian Institute of Technology Bombay, Mumbai 400076, India.
Biomed Mater. 2021 Aug 13;16(5). doi: 10.1088/1748-605X/ac177b.
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性的合成水凝胶相比，在配体密度和刚性耦合的天然生物聚合物网络中，细胞的反应预计会有所不同。在这里，我们研究了成纤维细胞在甲基丙烯酰化明胶（GelMA）凝胶上的张力动态平衡，GelMA 凝胶在组织工程应用中被广泛使用。在非常柔软的 5%-15% GelMA 凝胶（刚度为 10-100Pa 左右）上，发现成纤维细胞广泛扩散，并组装出明显的应力纤维和焦点黏附。使用胰蛋白酶诱导的分离来探测收缩力学，结果表明，只有黏附阻力对 GelMA 浓度敏感，而不是收缩力。改变收缩性的药物 blebbistatin 和 nocodazole 对焦点黏附大小表现出相反的影响，均导致黏附阻力降低和细胞变圆。然而，只有在 nocodazole 处理的细胞中才会影响细胞迁移。总的来说，我们的实验表明，在柔软的 GelMA 凝胶上，高配体密度介导的不依赖收缩性的黏附聚集可以驱动细胞扩散和迁移。
