Cellular and Molecular Bioengineering

, Volume 3, Issue 1, pp 50–59 | Cite as

Mechanical Forces in Endothelial Cells during Firm Adhesion and Early Transmigration of Human Monocytes

  • Zhijun Liu
  • Nathan J. Sniadecki
  • Christopher S. ChenEmail author


Transmigration of leukocytes across the endothelial barrier is a tightly controlled process involving multiple steps, including rolling adhesion, firm adhesion, and then penetration of leukocytes through the endothelial monolayer. While the key molecular signals have been described in great detail, we are only just beginning to unveil the mechanical forces involved in this process. Here, using a microfabricated system that reports traction forces generated by cells, we describe forces generated by endothelial cells during monocyte firm adhesion and transmigration. Average traction force across the endothelial monolayer increased dramatically when monocytes firmly adhered and transmigrated. Interestingly, the endothelial cell that was in direct contact with the monocyte exhibited much larger traction forces relative to its neighbors, and the direction of these traction forces aligned centripetally with respect to the monocyte. The increase in traction force occurred in the local subcellular zone of monocyte adhesion, and dissipated rapidly with distance. To begin to characterize the basis for this mechanical effect, we show that beads coated with anti-ICAM-1 or VCAM-1 antibodies bound to monolayers could reproduce this effect. Taken together, this study provides a new approach to examining the role of cellular mechanics in regulating leukocyte transmigration through the endothelium.


Transmigration Endothelial cells Mechanical forces Mechanotransduction Microposts MEMS 



We thank S. Shaw and F. Luscinskas for providing the GFP-tagged VE-cadherin adenovirus and D. Cohen for helpful discussions and technical support. This work was supported in part by grants from the National Institutes of Health (EB00262, HL73305, GM74048), the Army Research Office Multidisciplinary University Research Initiative, and the Material Research Science and Engineering Center of the Univ. of Pennsylvania and the RESBIO resource center of Rutgers University. N.J.S. acknowledges financial support from Ruth L. Kirschstein National Research Service Awards, and N.J.S. received additional support from the Hartwell Foundation.

Supplementary material

12195_2010_105_MOESM1_ESM.tif (6.1 mb)
SUPPLEMENTARY FIGURE 1 Traction forces in TEM-FA and TEM-ET monolayers. (a) Bar graph indicating increase in average traction force in both TEM-FA and TEM-ET monolayers during transmigration with no significant difference between the two (p = 0.10). *p < 0.05, indicates comparison against Ctrl; #p < 0.05, indicates comparison against TNF. Ctrl, TNF, and TEM conditions were plotted as references. (b) Bar graph indicating a significant difference in average traction forces between Ct and NCt cells in both TEM-FA and TEM-ET conditions. *p < 0.05, indicates comparison against Ct. Ctrl, TNF, and TEM conditions were plotted as references (PDF 6,224 kb)


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Copyright information

© Biomedical Engineering Society 2010

Authors and Affiliations

  • Zhijun Liu
    • 1
  • Nathan J. Sniadecki
    • 1
  • Christopher S. Chen
    • 1
    Email author
  1. 1.Department of BioengineeringUniversity of PennsylvaniaPhiladelphiaUSA

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