Nancy E. and Peter C. Meinig School of Biomedical Engineering, Cornell University, Ithaca, NY 14853.
John A. Paulson School of Engineering and Applied Sciences, Harvard University, Cambridge, MA 02138.
Proc Natl Acad Sci U S A. 2020 May 26;117(21):11387-11398. doi: 10.1073/pnas.1919394117. Epub 2020 May 8.
Altered microarchitecture of collagen type I is a hallmark of wound healing and cancer that is commonly attributed to myofibroblasts. However, it remains unknown which effect collagen microarchitecture has on myofibroblast differentiation. Here, we combined experimental and computational approaches to investigate the hypothesis that the microarchitecture of fibrillar collagen networks mechanically regulates myofibroblast differentiation of adipose stromal cells (ASCs) independent of bulk stiffness. Collagen gels with controlled fiber thickness and pore size were microfabricated by adjusting the gelation temperature while keeping their concentration constant. Rheological characterization and simulation data indicated that networks with thicker fibers and larger pores exhibited increased strain-stiffening relative to networks with thinner fibers and smaller pores. Accordingly, ASCs cultured in scaffolds with thicker fibers were more contractile, expressed myofibroblast markers, and deposited more extended fibronectin fibers. Consistent with elevated myofibroblast differentiation, ASCs in scaffolds with thicker fibers exhibited a more proangiogenic phenotype that promoted endothelial sprouting in a contractility-dependent manner. Our findings suggest that changes of collagen microarchitecture regulate myofibroblast differentiation and fibrosis independent of collagen quantity and bulk stiffness by locally modulating cellular mechanosignaling. These findings have implications for regenerative medicine and anticancer treatments.
胶原 I 型微结构的改变是伤口愈合和癌症的标志，通常归因于肌成纤维细胞。然而，胶原微结构对肌成纤维细胞分化的影响仍不清楚。在这里，我们结合实验和计算方法来验证这样一个假设，即纤维状胶原网络的微观结构通过独立于整体刚度的机械方式调节脂肪基质细胞（ASCs）的肌成纤维细胞分化。通过调整凝胶温度同时保持浓度恒定，来微制造具有受控纤维厚度和孔径的胶原凝胶。流变特性和模拟数据表明，与纤维较细、孔径较小的网络相比，纤维较厚、孔径较大的网络表现出更大的应变硬化。相应地，在具有较厚纤维的支架中培养的 ASC 更具收缩性，表达肌成纤维细胞标志物，并沉积更多延伸的纤维连接蛋白纤维。与肌成纤维细胞分化水平升高一致，在具有较厚纤维的支架中的 ASC 表现出更具促血管生成的表型，以收缩依赖性的方式促进内皮芽生。我们的研究结果表明，胶原微结构的改变通过局部调节细胞机械信号转导，独立于胶原数量和整体刚度来调节肌成纤维细胞分化和纤维化。这些发现对再生医学和抗癌治疗具有重要意义。
