Initial stress-kick is required for fluid shear stress-induced rate dependent activation of bone cells

Rommel G. Bacabac, Theo H. Smit, Margriet G. Mullender, Jack J.W.A. Van Loon, Jenneke Klein-Nulend*

*Corresponding author for this work

Research output: Contribution to journalArticleAcademicpeer-review

Abstract

The shear stress induced by the loading-mediated flow of interstitial fluid through the lacuno-canalicular network is a likely stimulus for bone cell adaptive responses. Furthermore, the magnitude of the cellular response is related to the rate of mechanical loading rather than its magnitude. Thus, bone cells might be very sensitive to sudden stress-kicks, as occuring e.g., during impact loading. There is evidence that cells change stiffness under stress, which might make them more sensitive to subsequent loading. We studied the influence of a stress-kick on the mechanosensitivity of MC3T3-E1 osteoblast-like cells under different peak shear rate conditions, as measured by nitric oxide production. MC3T3-E1 bone cells were treated with steady or pulsating fluid shear stress (PFSS) for 5 min with different peak rates (9.70, 17.5, and 22.0 Pa Hz) using varying frequencies (5 and 9 Hz), and amplitudes (0.70 and 0.31 Pa). PFSS treatment was done with or without fluid flow pretreatment phase, which removed the initial stress-kick by first applying a slow fluid flow increase. Nitric oxide production in response to fluid shear stress was rate dependent, but necessitated an initial stress-kick to occur. This suggests that high-rate stimuli condition bone cells to be more sensitive for high-frequency, low-amplitude loads.

Original languageEnglish
Pages (from-to)104-110
Number of pages7
JournalAnnals of Biomedical Engineering
Volume33
Issue number1
DOIs
Publication statusPublished - 1 Jan 2005
Externally publishedYes

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