Saunders Randi L, Hammer Daniel A
School of Engineering and Applied Sciences, Dept of Bioengineering, University of Pennsylvania, Philadelphia, Pennsylvania 19104.
Cell Mol Bioeng. 2010 Mar;3(1):60-67. doi: 10.1007/s12195-010-0112-4.
Angiogenesis is the process by which endothelial cells grow and disassemble into functional blood vessels. In this study, we examine the fundamental processes that control the assembly of endothelial cells into networks in vitro. Network assembly is known to be influenced by matrix mechanics and chemical signals. However, the roles of substrate stiffness and chemical signals in network formation is unclear. In this study, human umbilical vein endothelial cells (HUVECs) were seeded onto RGD or GFOGER functionalized polyacrylamide gels of varying stiffness. Cells were either treated with bFGF, VEGF, or left untreated and observed over time. We found that cells form stable networks on soft gels (Young's modulus 140 Pa) when untreated but that growth factors induce increased cell migration which leads to network instability. On stiffer substrates (Young's modulus 2500 Pa) cells do not assemble into networks either with or without growth factors in any combination. Our results indicate that cells assemble to networks below a critical compliance, that a critical cell density is needed for network formation, and that growth factors can inhibit network formation through an increase in motility.
血管生成是内皮细胞生长并分解形成功能性血管的过程。在本研究中，我们探究了体外控制内皮细胞组装成网络的基本过程。已知网络组装受基质力学和化学信号影响。然而，底物硬度和化学信号在网络形成中的作用尚不清楚。在本研究中，将人脐静脉内皮细胞（HUVECs）接种到具有不同硬度的RGD或GFOGER功能化聚丙烯酰胺凝胶上。细胞分别用碱性成纤维细胞生长因子（bFGF）、血管内皮生长因子（VEGF）处理，或不进行处理，并随时间观察。我们发现，未处理时细胞在软凝胶（杨氏模量140帕）上形成稳定网络，但生长因子会诱导细胞迁移增加，从而导致网络不稳定。在较硬的底物（杨氏模量2500帕）上，无论有无生长因子以任何组合处理，细胞都不会组装成网络。我们的结果表明，细胞在低于临界顺应性时组装成网络，网络形成需要临界细胞密度，并且生长因子可通过增加细胞运动性来抑制网络形成。
