In situ mechanical properties of the chondrocyte cytoplasm and nucleus

Gidon Ofek, Roman M. Natoli, Kyriacos A. Athanasiou

Research output: Contribution to journalArticle

47 Citations (Scopus)

Abstract

The way in which the nucleus experiences mechanical forces has important implications for understanding mechanotransduction. Knowledge of nuclear material properties and, specifically, their relationship to the properties of the bulk cell can help determine if the nucleus directly experiences mechanical loads, or if it is a signal transduction mechanism secondary to cell membrane deformation that leads to altered gene expression. Prior work measuring nuclear material properties using micropipette aspiration suggests that the nucleus is substantially stiffer than the bulk cell [Guilak, F., Tedrow, J.R., Burgkart, R., 2000. Viscoelastic properties of the cell nucleus. Biochem. Biophys. Res. Commun. 269, 781-786], whereas recent work with unconfined compression of single chondrocytes showed a nearly one-to-one correlation between cellular and nuclear strains [Leipzig, N.D., Athanasiou, K.A., 2008. Static compression of single chondrocytes catabolically modifies single-cell gene expression. Biophys. J. 94, 2412-2422]. In this study, a linearly elastic finite element model of the cell with a nuclear inclusion was used to simulate the unconfined compression data. Cytoplasmic and nuclear stiffnesses were varied from 1 to 7 kPa for several combinations of cytoplasmic and nuclear Poisson's ratios. It was found that the experimental data were best fit when the ratio of cytoplasmic to nuclear stiffness was 1.4, and both cytoplasm and nucleus were modeled as incompressible. The cytoplasmic to nuclear stiffness ratio is significantly lower than prior reports for isolated nuclei. These results suggest that the nucleus may behave mechanically different in situ than when isolated.

Original languageEnglish (US)
Pages (from-to)873-877
Number of pages5
JournalJournal of Biomechanics
Volume42
Issue number7
DOIs
StatePublished - May 11 2009
Externally publishedYes

Fingerprint

Chondrocytes
Cytoplasm
Stiffness
Gene expression
Mechanical properties
Materials properties
Signal transduction
Data compression
Poisson ratio
Data Compression
Cell membranes
Gene Expression
Intranuclear Inclusion Bodies
Cell Nucleus
Cells
Signal Transduction
Cell Membrane

Keywords

  • Gene transcription
  • Material properties
  • Mechanotransduction
  • Unconfined cytocompression

ASJC Scopus subject areas

  • Orthopedics and Sports Medicine
  • Rehabilitation
  • Biophysics
  • Biomedical Engineering

Cite this

In situ mechanical properties of the chondrocyte cytoplasm and nucleus. / Ofek, Gidon; Natoli, Roman M.; Athanasiou, Kyriacos A.

In: Journal of Biomechanics, Vol. 42, No. 7, 11.05.2009, p. 873-877.

Research output: Contribution to journalArticle

Ofek, Gidon ; Natoli, Roman M. ; Athanasiou, Kyriacos A. / In situ mechanical properties of the chondrocyte cytoplasm and nucleus. In: Journal of Biomechanics. 2009 ; Vol. 42, No. 7. pp. 873-877.
@article{1fb739251dac4592aaba2fefe4d54d16,
title = "In situ mechanical properties of the chondrocyte cytoplasm and nucleus",
abstract = "The way in which the nucleus experiences mechanical forces has important implications for understanding mechanotransduction. Knowledge of nuclear material properties and, specifically, their relationship to the properties of the bulk cell can help determine if the nucleus directly experiences mechanical loads, or if it is a signal transduction mechanism secondary to cell membrane deformation that leads to altered gene expression. Prior work measuring nuclear material properties using micropipette aspiration suggests that the nucleus is substantially stiffer than the bulk cell [Guilak, F., Tedrow, J.R., Burgkart, R., 2000. Viscoelastic properties of the cell nucleus. Biochem. Biophys. Res. Commun. 269, 781-786], whereas recent work with unconfined compression of single chondrocytes showed a nearly one-to-one correlation between cellular and nuclear strains [Leipzig, N.D., Athanasiou, K.A., 2008. Static compression of single chondrocytes catabolically modifies single-cell gene expression. Biophys. J. 94, 2412-2422]. In this study, a linearly elastic finite element model of the cell with a nuclear inclusion was used to simulate the unconfined compression data. Cytoplasmic and nuclear stiffnesses were varied from 1 to 7 kPa for several combinations of cytoplasmic and nuclear Poisson's ratios. It was found that the experimental data were best fit when the ratio of cytoplasmic to nuclear stiffness was 1.4, and both cytoplasm and nucleus were modeled as incompressible. The cytoplasmic to nuclear stiffness ratio is significantly lower than prior reports for isolated nuclei. These results suggest that the nucleus may behave mechanically different in situ than when isolated.",
keywords = "Gene transcription, Material properties, Mechanotransduction, Unconfined cytocompression",
author = "Gidon Ofek and Natoli, {Roman M.} and Athanasiou, {Kyriacos A.}",
year = "2009",
month = "5",
day = "11",
doi = "10.1016/j.jbiomech.2009.01.024",
language = "English (US)",
volume = "42",
pages = "873--877",
journal = "Journal of Biomechanics",
issn = "0021-9290",
publisher = "Elsevier Limited",
number = "7",

}

TY - JOUR

T1 - In situ mechanical properties of the chondrocyte cytoplasm and nucleus

AU - Ofek, Gidon

AU - Natoli, Roman M.

AU - Athanasiou, Kyriacos A.

PY - 2009/5/11

Y1 - 2009/5/11

N2 - The way in which the nucleus experiences mechanical forces has important implications for understanding mechanotransduction. Knowledge of nuclear material properties and, specifically, their relationship to the properties of the bulk cell can help determine if the nucleus directly experiences mechanical loads, or if it is a signal transduction mechanism secondary to cell membrane deformation that leads to altered gene expression. Prior work measuring nuclear material properties using micropipette aspiration suggests that the nucleus is substantially stiffer than the bulk cell [Guilak, F., Tedrow, J.R., Burgkart, R., 2000. Viscoelastic properties of the cell nucleus. Biochem. Biophys. Res. Commun. 269, 781-786], whereas recent work with unconfined compression of single chondrocytes showed a nearly one-to-one correlation between cellular and nuclear strains [Leipzig, N.D., Athanasiou, K.A., 2008. Static compression of single chondrocytes catabolically modifies single-cell gene expression. Biophys. J. 94, 2412-2422]. In this study, a linearly elastic finite element model of the cell with a nuclear inclusion was used to simulate the unconfined compression data. Cytoplasmic and nuclear stiffnesses were varied from 1 to 7 kPa for several combinations of cytoplasmic and nuclear Poisson's ratios. It was found that the experimental data were best fit when the ratio of cytoplasmic to nuclear stiffness was 1.4, and both cytoplasm and nucleus were modeled as incompressible. The cytoplasmic to nuclear stiffness ratio is significantly lower than prior reports for isolated nuclei. These results suggest that the nucleus may behave mechanically different in situ than when isolated.

AB - The way in which the nucleus experiences mechanical forces has important implications for understanding mechanotransduction. Knowledge of nuclear material properties and, specifically, their relationship to the properties of the bulk cell can help determine if the nucleus directly experiences mechanical loads, or if it is a signal transduction mechanism secondary to cell membrane deformation that leads to altered gene expression. Prior work measuring nuclear material properties using micropipette aspiration suggests that the nucleus is substantially stiffer than the bulk cell [Guilak, F., Tedrow, J.R., Burgkart, R., 2000. Viscoelastic properties of the cell nucleus. Biochem. Biophys. Res. Commun. 269, 781-786], whereas recent work with unconfined compression of single chondrocytes showed a nearly one-to-one correlation between cellular and nuclear strains [Leipzig, N.D., Athanasiou, K.A., 2008. Static compression of single chondrocytes catabolically modifies single-cell gene expression. Biophys. J. 94, 2412-2422]. In this study, a linearly elastic finite element model of the cell with a nuclear inclusion was used to simulate the unconfined compression data. Cytoplasmic and nuclear stiffnesses were varied from 1 to 7 kPa for several combinations of cytoplasmic and nuclear Poisson's ratios. It was found that the experimental data were best fit when the ratio of cytoplasmic to nuclear stiffness was 1.4, and both cytoplasm and nucleus were modeled as incompressible. The cytoplasmic to nuclear stiffness ratio is significantly lower than prior reports for isolated nuclei. These results suggest that the nucleus may behave mechanically different in situ than when isolated.

KW - Gene transcription

KW - Material properties

KW - Mechanotransduction

KW - Unconfined cytocompression

UR - http://www.scopus.com/inward/record.url?scp=64549089619&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=64549089619&partnerID=8YFLogxK

U2 - 10.1016/j.jbiomech.2009.01.024

DO - 10.1016/j.jbiomech.2009.01.024

M3 - Article

C2 - 19261283

AN - SCOPUS:64549089619

VL - 42

SP - 873

EP - 877

JO - Journal of Biomechanics

JF - Journal of Biomechanics

SN - 0021-9290

IS - 7

ER -