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Biomechanics and Modeling in Mechanobiology

, Volume 14, Issue 4, pp 851–863 | Cite as

Finite element analysis of the pressure-induced deformation of Schlemm’s canal endothelial cells

  • Rocio Vargas-Pinto
  • Julia Lai
  • Haiyan Gong
  • C. Ross Ethier
  • Mark Johnson
Original Paper

Abstract

The endothelial cells lining the inner wall of Schlemm’s canal (SC) in the eye are relatively unique in that they support a basal-to-apical pressure gradient that causes these cells to deform, creating giant vacuoles and transendothelial pores through which the aqueous humor flows. Glaucoma is associated with an increased resistance to this flow. We used finite element modeling and estimates of cell modulus made using atomic force microscopy to characterize the pressure-induced deformation of SC cells and to estimate the maximum pressure drop that SC cells can support. We examined the effects of cell geometry, cell stiffness, and the contribution of the cell cortex to support the pressure-generated load. We found that the maximum strain generated by this loading occurs at the points of cell–substrate attachment and that the cortex of the cells bears nearly all of this load. The ability of these cells to support a significant transcellular pressure drop is extremely limited (on the order of 5 mmHg or less) unless these cells either stiffen very considerably with increasing deformation or have substantial attachments to their substratum away from their periphery. This puts limits on the flow resistance that this layer can generate, which has implications regarding the site where the bulk of the flow resistance is generated in healthy and glaucomatous eyes.

Keywords

Aqueous humor outflow resistance Strain Cell cortex Glaucoma 

Notes

Acknowledgments

This work was supported by funding from the National Glaucoma Research program of the Bright Focus Foundation, from the Georgia Research Alliance, and from the National Institutes of Health, grants R01 EY019696, EY022634, and T32 EY007128. This research was supported in part through the computational resources provided by the Quest high-performance computing facility at Northwestern University. We thank Renovo Neural Inc., (Cleveland, OH) for the service of SBSEM imaging.

Supplementary material

10237_2014_640_MOESM1_ESM.pdf (65 kb)
Supplementary material 1 (pdf 64 KB)
10237_2014_640_MOESM2_ESM.tif (38.6 mb)
Supplementary material 2 (tif 39510 KB)

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Copyright information

© Springer-Verlag Berlin Heidelberg 2014

Authors and Affiliations

  • Rocio Vargas-Pinto
    • 1
  • Julia Lai
    • 2
    • 3
  • Haiyan Gong
    • 2
    • 3
  • C. Ross Ethier
    • 4
    • 5
  • Mark Johnson
    • 6
  1. 1.Department of Biomedical EngineeringNorthwestern UniversityEvanstonUSA
  2. 2.Departments of Anatomy and NeurobiologyBoston University School of MedicineBostonUSA
  3. 3.Department of OphthalmologyBoston University School of MedicineBostonUSA
  4. 4.Wallace H. Coulter Department of Biomedical EngineeringGeorgia Institute of TechnologyAtlantaUSA
  5. 5.Departments of Biomedical Engineering and OphthalmologyEmory UniversityAtlantaUSA
  6. 6.Departments of Biomedical Engineering, Mechanical Engineering and OphthalmologyNorthwestern UniversityEvanstonUSA

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