Biomechanics of single chondrocytes under direct shear

Gidon Ofek, Enda P. Dowling, Robert M. Raphael, J. Patrick McGarry, Kyriacos A. Athanasiou

Research output: Contribution to journalArticle

30 Scopus citations

Abstract

Articular chondrocytes experience a variety of mechanical stimuli during daily activity. One such stimulus, direct shear, is known to affect chondrocyte homeostasis and induce catabolic or anabolic pathways. Understanding how single chondrocytes respond biomechanically and morphologically to various levels of applied shear is an important first step toward elucidating tissue level responses and disease etiology. To this end, a novel videocapture method was developed in this study to examine the effect of direct shear on single chondrocytes, applied via the controlled lateral displacement of a shearing probe. Through this approach, precise force and deformation measurements could be obtained during the shear event, as well as clear pictures of the initial cell-to-probe contact configuration. To further study the nonuniform shear characteristics of single chondrocytes, the probe was positioned in three different placement ranges along the cell height. It was observed that the apparent shear modulus of single chondrocytes decreased as the probe transitioned from being close to the cell base (4.1 ± 1.3kPa), to the middle of the cell (2.6 ± 1.1 kPa), and then near its top (1.7 ± 0.8 kPa). In addition, cells experienced the greatest peak forward displacement (̃30% of their initial diameter) when the probe was placed low, near the base. Forward cell movement during shear, regardless of its magnitude, continued until it reached a plateau at ̃35% shear strain forall probe positions, suggesting that focal adhesions become activated at this shear level to firmly adhere the cell to its substrate. Based on intracellular staining, the observed heightspecific variation in cell shear stiffness and plateau in forward cellmovement appeared to be due to a rearrangement of focal adhesions and actin at higher shear strains. Understandingthe fundamental mechanisms at play during shear of single cells will help elucidate potential treatments for chondrocyte pathology and loading regimens related to cartilage health and disease.

Original languageEnglish (US)
Pages (from-to)153-162
Number of pages10
JournalBiomechanics and Modeling in Mechanobiology
Volume9
Issue number2
DOIs
StatePublished - Apr 2010
Externally publishedYes

Keywords

  • Actin
  • Articular cartilage
  • Cell mechanics
  • Focal adhesions

ASJC Scopus subject areas

  • Biotechnology
  • Mechanical Engineering
  • Modeling and Simulation

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  • Cite this

    Ofek, G., Dowling, E. P., Raphael, R. M., McGarry, J. P., & Athanasiou, K. A. (2010). Biomechanics of single chondrocytes under direct shear. Biomechanics and Modeling in Mechanobiology, 9(2), 153-162. https://doi.org/10.1007/s10237-009-0166-1