Cellular and Molecular Bioengineering

, Volume 3, Issue 1, pp 60–67

Assembly of Human Umbilical Vein Endothelial Cells on Compliant Hydrogels



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 are 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.


Polyacrylamide gel Substrate stiffness/compliance bFGF VEGF Angiogenesis 

Supplementary material

12195_2010_112_MOESM1_ESM.tif (32.2 mb)
FIGURE S1The more sparse cells are on soft substrates the less they move. HUVECs were seeded on 140 Pa polyacrylamide gels linked with 0.1 mM RGD. Cells at each density were tracked and the average velocity was plotted. As the cells were plated at higher densities, they were able to crawl more quickly. Via ANOVA, p < 0.001 between groups (TIF 32925 kb)

Supplementary material 2 (AVI 15730 kb)

Supplementary material 3 (AVI 14981 kb)


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Copyright information

© Biomedical Engineering Society 2010

Authors and Affiliations

  1. 1.Department of Bioengineering, School of Engineering and Applied ScienceUniversity of PennsylvaniaPhiladelphiaUSA

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