Cell Morphology and Gap Junction Communication in the Annulus Fibrosus

Mechanical loading of the intervertebral disc during everyday activity can contribute to the regulation of cell-mediated remodeling processes and may induce degeneration or disease processes. This study aimed to characterize the morphology of cells, and investigate whether functional gap junctions exist in degenerated and scoliotic human intervertebral discs. Another aim was to investigate the gene expression response of bovine annulus fibrosus to mechanical load and whether this response is altered with disruption of gap junction communication. Morphological studies have revealed three distinct cell morphologies in the human annulus fibrosus. Fluorescence recovery after photobleaching has shown that annulus cells can communicate functionally via gap junctions. This ability is not seen in all samples which may be due to the pathological nature of the tissue. Gene expression of type I collagen, connexion-43, aggrecan and MMP-3 was up regulated in response to unloaded free swelling culture conditions and down regulated after 4 hours of loading in culture. Gene expression in the octanol treated unloaded samples was significantly lower than the untreated unloaded samples, and gene expression in the octanol treated loaded samples was significantly higher than the untreated loaded samples. These studies have contributed to an improved characterization of the cells in the annulus fibrosus.

Year	Entry
1995	Ohshima H, Urban JPG, Bergel DH. Effect of static load on matrix synthesis rates in the intervertebral disc measured in vitro by a new perfusion technique. J Orthop Res. January 1995;13(1):22-29.
1987	Stokes IAF. Surface strain on human intervertebral discs. J Orthop Res. 1987;5(3):348-355.
2007	Desrochers J. Intercellular Communication and in Situ Strains in the Annulus Fibrosus Under High Flexion Loads [Master's thesis]. Calgary, AB: University of Calgary; June 2007.
2005	Cherian PP, Siller-Jackson AJ, Gu S, Wang X, Bonewald LF, Sprague E, Jiang JX. Mechanical strain opens connexin 43 hemichannels in osteocytes: a novel mechanism for the release of prostaglandin. Mol Biol Cell. July 2005;16(7):3100-3106.
2005	Iatridis JC, MacLean JJ, Ryan DA. Mechanical damage to the intervertebral disc annulus fibrosus subjected to tensile loading. J Biomech. March 2005;38(3):557-565.
1996	Antoniou J, Steffen T, Nelson F, Winterbottom N, Hollander AP, Poole RA, Aebi M, Alini M. The human lumbar intervertebral disc: evidence for changes in the biosynthesis and denaturation of the extracellular matrix with growth, maturation, ageing, and degeneration. J Clin Invest. August 15, 1996;98(4):996-1003.
2006	Roberts S, Evans H, Trivedi J, Menage J. Histology and pathology of the human intervertebral disc. J Bone Joint Surg. April 2006;88A(suppl 2):10-14.
2004	Wagner DR, Lotz JC. Theoretical model and experimental results for the nonlinear elastic behavior of human annulus fibrosus. J Orthop Res. July 2004;22(4):901-909.
1998	Lotz JC, Colliou OK, Chin JR, Duncan NA, Liebenberg E. Compression-induced degeneration of the intervertebral disc: an in vivo mouse model and finite-element study. Spine. December 1, 1998;23(23):2493-2506.
2004	Walsh AJL, Lotz JC. Biological response of the intervertebral disc to dynamic loading. J Biomech. March 2004;37(3):329-337.
2001	Gruber HE, Ma D, Hanley EN Jr, Ingram J, Yamaguchi DT. Morphologic and molecular evidence for gap junctions and connexin 43 and 45 expression in annulus fibrosus cells from the human intervertebral disc. J Orthop Res. September 2001;19(5):985-989.
2002	Bruehlmann SB, Rattner JB, Matyas JR, Duncan NA. Regional variations in the cellular matrix of the annulus fibrosus of the intervertebral disc. J Anat. August 2002;201(2):159-171.
1960	Nachemson A. Lumbar intradiscal pressure: experimental studies on post-mortem material. Acta Orthop Scand. 1960;31(suppl 43):1-104.
2006	Kelly EJ. Functional Gap Junction Communication and Its Mechanobiological Role in the Outer Annulus Fibrosus [Master's thesis]. Calgary, AB: University of Calgary; August 2006.
1998	Errington RJ, Puustjarvi K, White IRF, Roberts S, Urban JPG. Characterisation of cytoplasm-filled processes in cells of the intervertebral disc. J Anat. April 1998;192(3):369-378.
2000	Adams MA, Freeman BJC, Morrison HP, Nelson IW, Dolan P. Mechanical initiation of intervertebral disc degeneration. Spine. July 1, 2000;25(13):1625-1636.
1996	Ebara S, Iatridis JC, Setton LA, Foster RJ, Mow VC, Weidenbaum M. Tensile properties of nondegenerate human lumbar anulus fibrosus. Spine. March 15, 1996;21(4):452-461.
2003	Urban JPG, Roberts S. Degeneration of the intervertebral disc. Arthritis Res Ther. 2003;5(3):120-130.
2006	Moore KL, Dalley AF. Clinically Oriented Anatomy. 5th ed. Philadelphia, PA: Lippincott Williams & Wilkins; 2006.
1995	Buckwalter JA. Aging and degeneration of the human intervertebral disc. Spine. June 1995;20(11):1307-1314.
2002	Boos N, Weissbach S, Rohrbach H, Weiler C, Spratt KF, Nerlich AG. Classification of age-related changes in lumbar intervertebral discs. Spine. December 1, 2002;27(23):2631-2644.

Year

Entry

1995

Ohshima H, Urban JPG, Bergel DH. Effect of static load on matrix synthesis rates in the intervertebral disc measured in vitro by a new perfusion technique. J Orthop Res. January 1995;13(1):22-29.

1987

Stokes IAF. Surface strain on human intervertebral discs. J Orthop Res. 1987;5(3):348-355.

2007

Desrochers J. Intercellular Communication and in Situ Strains in the Annulus Fibrosus Under High Flexion Loads [Master's thesis]. Calgary, AB: University of Calgary; June 2007.

2005

Cherian PP, Siller-Jackson AJ, Gu S, Wang X, Bonewald LF, Sprague E, Jiang JX. Mechanical strain opens connexin 43 hemichannels in osteocytes: a novel mechanism for the release of prostaglandin. Mol Biol Cell. July 2005;16(7):3100-3106.

2005

Iatridis JC, MacLean JJ, Ryan DA. Mechanical damage to the intervertebral disc annulus fibrosus subjected to tensile loading. J Biomech. March 2005;38(3):557-565.