Integrin - dependent mechanotransduction in mechanically stimulated human annulus fibrosus cells: evidence for an alternative mechanotransduction pathway operating with degeneration.

Intervertebral disc (IVD) cells derived from degenerate tissue respond aberrantly to mechanical stimuli, potentially due to altered mechanotransduction pathways. Elucidation of the altered, or alternative, mechanotransduction pathways operating with degeneration could yield novel targets for the treatment of IVD disease. Our aim here was to investigate the involvement of RGD-recognising integrins and associated signalling molecules in the response to cyclic tensile strain (CTS) of human annulus fibrosus (AF) cells derived from non-degenerate and degenerate IVDs.

The involvement of interleukin-1 and interleukin-4 in the response of human annulus fibrosus cells to cyclic tensile strain: an altered mechanotransduction pathway with degeneration.

Introduction: Recent evidence suggests that intervertebral disc (IVD) cells derived from degenerative tissue are unable to respond to physiologically relevant mechanical stimuli in the 'normal' anabolic manner, but instead respond by increasing matrix catabolism. Understanding the nature of the biological processes which allow disc cells to sense and respond to mechanical stimuli (a process termed 'mechanotransduction') is important to ascertain whether these signalling pathways differ with disease. The aim here was to investigate the involvement of interleukin (IL)-1 and IL-4 in the response of annulus fibrosus (AF) cells derived from nondegenerative and degenerative tissue to cyclic tensile strain to determine whether cytokine involvement differed with IVD degeneration.

The response of human anulus fibrosus cells to cyclic tensile strain is frequency-dependent and altered with disc degeneration.

Objective: Mechanical loads are important for homeostasis of the intervertebral disc (IVD) cell matrix, with physiologic and nonphysiologic loads leading to matrix anabolism and catabolism, respectively. Previous investigations into the effects of load on disc cells have predominantly used animal models, with the limited number of human studies focusing primarily on nucleus pulposus cells. The aim of this study was to examine the effect of cyclic tensile strain (CTS) on human anulus fibrosus (AF) cells to ascertain whether the response was frequency-dependent and to compare AF cells derived from nondegenerated and degenerated tissue samples.

Tissue section AFM: In situ ultrastructural imaging of native biomolecules.

Conventional approaches for ultrastructural high-resolution imaging of biological specimens induce profound changes in bio-molecular structures. By combining tissue cryo-sectioning with non-destructive atomic force microscopy (AFM) imaging we have developed a methodology that may be applied by the non-specialist to both preserve and visualize bio-molecular structures (in particular extracellular matrix assemblies) in situ. This tissue section AFM technique is capable of: i) resolving nm-microm scale features of intra- and extracellular structures in tissue cryo-sections; ii) imaging the same tissue region before and after experimental interventions; iii) combining ultrastructural imaging with complimentary microscopical and micromechanical methods.

Regulation of catabolic gene expression in normal and degenerate human intervertebral disc cells: implications for the pathogenesis of intervertebral disc degeneration.

Introduction: The aim of this study was to compare the effects of tumour necrosis factor-alpha (TNF-alpha) and interleukin-1-beta (IL-1beta) on protease and catabolic cytokine and receptor gene expression in normal and degenerate human nucleus pulposus cells in alginate culture.

Methods: Cells isolated from normal and degenerate nucleus pulposus regions of human intervertebral discs were cultured in alginate pellets and stimulated by the addition of 10 ng/mL TNF-alpha or IL-1beta for 48 hours prior to RNA extraction. Quantitative real-time polymerase chain reaction was used to assess the effect of TNF-alpha or IL-beta stimulation on the expression of matrix metalloproteinase (MMP)-3, -9 and -13, TNF-alpha, TNF receptor 1 (TNF-R1), TNF receptor 2 (TNF-R2), IL-1alpha, IL-1beta, IL-1 receptor 1 (IL-1R1) and IL-1 receptor antagonist (IL-1Ra).