On the electrophysiological response of bone cells using a Stokesian fluid stimulus probe for delivery of quantifiable localized picoNewton level forces

Danielle Wu, Peter Ganatos, David C. Spray, Sheldon Weinbaum

Research output: Contribution to journalArticle

21 Citations (Scopus)

Abstract

A Stokesian fluid stimulus probe (SFSP), capable of delivering quantifiable pN level hydrodynamic forces, is developed to distinguish the electrophysiological response of the cell process and cell body of osteocyte-like MLO-Y4 cells without touching the cell or its substrate. The hydrodynamic disturbance is a short lived (100ms), constant strength pressure pulse that propagates nearly instantaneously through the medium creating a nearly spherical expanding fluid bolus surrounding a 0.8γm micropipette tip. Laboratory model experiments show that the growth of the bolus and the pressure field can be closely modeled by quasi-steady Stokes flow through a circular orifice provided the tip Reynolds number, Ret<0.03. By measuring the deflection of the dendritic processes between discrete attachment sites, and applying a detailed ultrastructural model for the central actin filament bundle within the process, one is able to calculate the forces produced by the probe using elastic beam theory. One finds that forces between 1 and 2.3pN are sufficient to initiate electrical signaling when applied to the cell process, but not the much softer cell body. Even more significantly, cellular excitation by the process only occurs when the probe is directed at discrete focal attachment sites along the cell process. This suggests that electrical signaling is initiated at discrete focal attachments along the cell process and that these sites are likely integrin-mediated complexes associated with stretch-activated ion channels though their molecular structure is unknown.

Original languageEnglish (US)
Pages (from-to)1702-1708
Number of pages7
JournalJournal of Biomechanics
Volume44
Issue number9
DOIs
StatePublished - Jun 3 2011

Fingerprint

Bone
Bone and Bones
Fluids
Hydrodynamics
Cells
Orifices
Molecular structure
Reynolds number
Osteocytes
Ions
Substrates
Molecular Structure
Actin Cytoskeleton
Ion Channels
Integrins
Experiments
Blood Pressure
Pressure
Growth
Cell Body

Keywords

  • Low reynolds number jets
  • Micropipette ejection
  • Molecular force probes
  • Osteocyte mechanotransduction
  • Whole-cell voltage patch-clamp

ASJC Scopus subject areas

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

Cite this

On the electrophysiological response of bone cells using a Stokesian fluid stimulus probe for delivery of quantifiable localized picoNewton level forces. / Wu, Danielle; Ganatos, Peter; Spray, David C.; Weinbaum, Sheldon.

In: Journal of Biomechanics, Vol. 44, No. 9, 03.06.2011, p. 1702-1708.

Research output: Contribution to journalArticle

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