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Cyclic tensile stress exerts a protective effect on intervertebral disc cells
Gwendolyn Sowa1, Sudha Agarwal
1Department of Physical Medicine and Rehabilitation, Ferguson Laboratory for Orthopaedic Research, Pittsburgh, PA 15213, USA.
American Journal of Physical Medicine & Rehabilitation
|January 23, 2008
Summary
Physiologic tensile stress, a key component of motion-based therapies, reduces inflammatory gene expression in annulus fibrosus cells. This suggests mechanical forces may protect the intervertebral disc from inflammation-induced damage.
Area of Science:
- Biomaterials Science
- Cell Biology
- Biomechanical Engineering
Background:
- Intervertebral disc degeneration is linked to mechanical forces and inflammation.
- Annulus fibrosus cells are crucial for disc structure and function.
- Understanding cellular responses to mechanical stress is vital for developing effective therapies.
Purpose of the Study:
- To investigate the protective effects of tensile stress on annulus fibrosus cells.
- To test the hypothesis that physiologic tensile stress mitigates inflammation-induced catabolic gene expression.
- To elucidate the mechanisms underlying the benefits of motion-based therapies.
Main Methods:
- Fibrochondrocytes were isolated from rat annulus fibrosus.
- Cells were exposed to inflammatory stimulus (IL-1 beta) and/or tensile stress (6% at 0.05 Hz).
- Gene expression changes, including catabolic mediators and matrix components, were analyzed.
Main Results:
- Inflammatory stimulus increased catabolic gene expression.
- Combined inflammation and tensile stress reduced catabolic gene expression by approximately 50%.
- Tensile stress alone decreased matrix metalloprotease-13 expression; Collagen II expression was modestly reduced in an inflammatory environment.
Conclusions:
- Moderate tensile stress acts as a protective signal in annulus fibrosus cells under inflammatory conditions.
- Tensile stress reduces the expression of catabolic mediators, suggesting an anti-inflammatory action.
- Motion-based therapies may benefit the intervertebral disc by applying tensile stress to the annulus fibrosus.
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