Influence of extracellular osmolarity and mechanical stimulation on gene expression of intervertebral disc cells
Open Access
- 13 June 2007
- journal article
- research article
- Published by Wiley in Journal of Orthopaedic Research
- Vol. 25 (11), 1513-1522
- https://doi.org/10.1002/jor.20436
Abstract
Intervertebral discs (IVD) have a higher extracellular osmolarity than most other tissues; moreover their osmolarity changes by around 25% during each diurnal cycle. In this study, changes in aggrecan, collagen I and collagen II expression of IVD cells were examined after exposure to osmotic environment alterations or mechanical stimulation under different osmotic conditions. Human and bovine IVD cells seeded in three‐dimensional (3D) collagen type I matrices were cultured under hypo‐osmotic (300 mOsm), iso‐osmotic (400 mOsm), or hyperosmotic (500 mOsm) conditions. Osmolarity‐induced changes in gene expression of IVD cells were measured after 5 days. Load‐induced changes in gene expression under the different osmotic conditions were measured after application of hydrostatic pressure (0.25 MPa, 0.1 Hz, 30 min) or cyclic strain (4%, 1 Hz, 24 h). The results showed that IVD cells respond strongly to changes in the osmotic environment by altering mRNA expression. Human cells cultured over 5 days increased expression of aggrecan and collagen II in both nucleus and annulus cells under increasing osmolarity. In contrast, collagen I expression was inhibited at high osmolarity in both cell types. Mechanically induced alterations in gene expression appear to have only modest effects on matrix protein expression, but the same stimulus partly resulted in an inhibition or stimulation of gene expression, depending on the osmotic conditions. This study showed that the osmotic environment does not only have an appreciable effect on gene expression but also affects responses to mechanical stimuli. This suggests that the osmotic conditions cannot be ignored when examining physiological and pathological behavior of IVD cells. © 2007 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 25:1513–1522, 2007This publication has 28 references indexed in Scilit:
- Hyperosmotically Induced Volume Change and Calcium Signaling in Intervertebral Disk Cells: The Role of the Actin CytoskeletonBiophysical Journal, 2002
- New In Vivo Measurements of Pressures in the Intervertebral Disc in Daily LifeSpine, 1999
- Functional Significance of Cell Volume Regulatory MechanismsPhysiological Reviews, 1998
- Proteoglycan synthesis in the intervertebral disk nucleus: the role of extracellular osmolalityAmerican Journal of Physiology-Cell Physiology, 1997
- 'Stress' distributions inside intervertebral discsThe Journal of Bone and Joint Surgery. British volume, 1996
- Surface strain on human intervertebral discsJournal of Orthopaedic Research, 1987
- A finite element study of a lumbar motion segment subjected to pure sagittal plane momentsJournal of Biomechanics, 1986
- Swelling pressure of the inervertebral disc: Influence of proteoglycan and collagen contentsBiorheology, 1985
- Swelling of the Intervertebral Discin VitroConnective Tissue Research, 1981
- Swelling pressures of proteoglycans at the concentrations found in cartilaginous tissuesBiorheology, 1979