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J Orthop Res. 2006 Oct;24(10):1967-73.

Frequency response of pig intervertebral disc cells subjected to dynamic hydrostatic pressure.

Author information

1
Department of Mechanical Engineering, McMaster University, Hamilton, Ontario, Canada L8S 4L7, and Department of Orthopaedics and Rehabilitation, University of Iowa Hospitals and Clinics, Iowa City 52242, USA. kasram@mcmaster.ca

Abstract

The pathogenesis of vibration-induced disorders of intervertebral disc at the cellular level is largely unknown. Dynamic loads with frequencies close to that of the in vivo human spine resonant frequency (4-6 Hz) have a destructive effect, which may induce extracellular disc matrix (ECM) degradation. To investigate this issue, three-dimensional (3D) alginate cultures of normal pig intervertebral disc nucleus and inner annulus cells were tested under dynamic hydrostatic loading. Alginate cultures of each region were divided into six groups; five groups were exposed to cyclic hydrostatic pressures of frequencies 1, 3, 5, 8, and 10 Hz with the same amplitude (1 MPa), and group 6 was the control group (no loading). Cultures of different groups were loaded for 3 days (30 min daily) in a hydraulic chamber. Effects of loading frequency on disc collagen and protein metabolism were investigated by measuring 3H-proline-labeled proteins associated with the cells in the extracellular matrix and release of 3H-proline-labeled molecules into culture medium. The results indicated a poor synthesis rate and more degradation near the 5 Hz frequency. The repeatability of experiments was verified by performing two experiments with the same protocol. Both experiments indicated that a threshold frequency of around 5 Hz disrupted protein metabolism.

PMID:
16900539
DOI:
10.1002/jor.20253
[Indexed for MEDLINE]
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