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Free Axial Vibrations At 0 to 200 Hz Positively Affect Extracellular Matrix Messenger Ribonucleic Acid Expression in Bovine Nucleus Pulposi

Desmoulin, Geoffrey T. MSc*; Reno, Carol R. MSc; Hunter, Christopher J. PhD†‡

doi: 10.1097/BRS.0b013e3181c2a8ec
Basic Science

Study Design. Bovine caudal intervertebral discs (IVDs) were exposed to free axial vibration for 10 to 60 minutes at 0 to 0.5g and 0 to 200 Hz. Expression of messenger ribonucleic acid for aggrecan, collagen type I, collagen type II, biglycan, decorin, and versican were assayed, as was apoptosis.

Objective. To determine the vibration conditions which are most effective in altering intervertebral disc IVD gene expression.

Summary of Background Data. Various studies have suggested widely varying effects of vibration in the IVD, ranging from harmful (increased risk of degeneration) to beneficial (increased analgesia) to neutral (no effect).

Methods. Vibration was applied using a custom designed voice coil system, which generated controlled motion in the axial direction. Gene expression in the nucleus pulposus was assessed using RT-PCR and the SYBR green chemistry; apoptosis was assessed using TUNEL staining.

Results. Expression of messenger ribonucleic acids for biglycan, collagen type I, collagen type II, decorin, and versican were significantly affected by vibration duration, frequency, and amplitude. Aggrecan was unaffected. Of the 3 factors, amplitude had the largest and widest effect.

Conclusion. Expression of extracellular matrix genes was significantly upregulated at high amplitudes (>0.4 g) in as little as 10 minutes. This may indicate a potential therapeutic stimulus; periodic application of controlled vibration could positively influence matrix maintenance. Further studies on the protein level and long-term effects are warranted.

Previous studies have indicated a mixed effect of vibrations in the human spine. In this study, controlled axial vibration was applied to bovine IVDs, and gene expression in the nucleus pulposus was measured. Several extracellular matrix genes were affected, suggesting a sensitivity to vibration.

From the *Optima Health Solutions International Corporation (KKT International), Vancouver, British Columbia, Canada; †McCaig Institute for Bone and Joint Health; and ‡Centre for Bioengineering Research and Education, University of Calgary, and Department of Mechanical and Manufacturing Engineering, Schulich School of Engineering, University of Calgary, Calgary, Alberta, Canada.

Acknowledgment date: June 12, 2009. First revision date: July 7, 2009. Acceptance date: August 31, 2009.

The manuscript submitted does not contain information about medical device(s)/drug(s).

Corporate/Industry funds were received in support of this work. No benefits in any form have been or will be received from a commercial party related directly or indirectly to the subject of this manuscript.

Supported by a research contract from Optima Health Solutions International Corporation.

C.J.H. is an Alberta Heritage Foundation for Medical Research Scholar. G.T.D. is an employee of Optima Health Solutions International Corp. and is sponsored in part by the National Research Council of Canada's Industrial Research Assistance Program.

Address correspondence and reprint requests to Christopher J. Hunter, Department of Mechanical and Manufacturing Engineering, University of Calgary, 2500 University Drive NW, Calgary, Alberta T2N 1N4, Canada; E-mail: chunter@ucalgary.ca

© 2010 Lippincott Williams & Wilkins, Inc.