title: A three-dimensional collagen matrix as a suitable culture system for the comparison of cyclic strain and hydrostatic pressure effects on intervertebral disc cells.
abstract: OBJECTIVE
  To study intervertebral disc cell mechanobiology, the authors developed experimental systems that allow the application of cyclic strain and intermittent hydrostatic pressure (IHP) on isolated disc cells under equal three-dimensional (3D) culture conditions. The purpose of the study was to characterize disc cell proliferation, viability, morphology, and gene expression in 3D collagen matrices.
  
  
  METHODS
  The effects of cyclic strain (1, 2, 4, and 8% strain; 1 Hz) and IHP (0.25 MPa, 0.1 Hz) on gene expression (real-time polymerase chain reaction) of anabolic and catabolic matrix proteins were investigated and compared with those derived from mechanically unstimulated controls. Intervertebral disc cells proliferated in the collagen gels (mean viability 91.6%) and expressed messenger RNA for collagen I, collagen II, aggrecan, matrix metalloproteinase (MMP)-2, and MMP-3. Morphologically, both spindle-shaped cells with longer processes and rounded cells were detected in the collagen scaffolds. Cyclic strain increased collagen II and aggrecan expression and decreased MMP-3 expression of anulus fibrosus cells. No significant difference between the four strain magnitudes was found. Intermittent hydrostatic pressure tended to increase collagen I and aggrecan expression of nucleus cells and significantly decreased MMP-2 and -3 expression of nucleus cells, whereas aggrecan expression of anulus cells tended to decrease.
  
  
  CONCLUSIONS
  Based on these results, the collagen matrix appeared to be a suitable substrate to apply both cyclic strain and IHP to intervertebral disc cells under 3D culture conditions. Individual variations may be influenced by the extent of degeneration of the disc specimens from which the cells were isolated. This experimental setup may be suitable for studying the influence of degeneration on the disc cell response to mechanical stimuli.
authors.affiliation: Institute of Orthopaedic Research and Biomechanics, University of Ulm, Germany. cornelia.neidlinger-wilke@medizin.uni-ulm.de
authors.forename: Cornelia
authors.initials: C
authors.lastname: Neidlinger-Wilke
authors.forename: Karin
authors.initials: K
authors.lastname: Würtz
authors.forename: Astrid
authors.initials: A
authors.lastname: Liedert
authors.forename: Carla
authors.initials: C
authors.lastname: Schmidt
authors.forename: Wolfgang
authors.initials: W
authors.lastname: Börm
authors.forename: Anita
authors.initials: A
authors.lastname: Ignatius
authors.forename: Hans-Joachim
authors.initials: HJ
authors.lastname: Wilke
authors.forename: Lutz
authors.initials: L
authors.lastname: Claes
mesh_terms: D053674:Aggrecans; D001696:Biomechanical Phenomena; D001706:Biopsy; D002465:Cell Movement; D024042:Collagen Type I / Q000096:biosynthesis* / Q000235:genetics; D024043:Collagen Type II / Q000096:biosynthesis* / Q000235:genetics; D017931:DNA Primers / Q000235:genetics; D004867:Equipment Design; D005109:Extracellular Matrix / Q000235:genetics / Q000378:metabolism*; D016326:Extracellular Matrix Proteins / Q000235:genetics / Q000378:metabolism; D015870:Gene Expression / Q000235:genetics; D006801:Humans; D006874:Hydrostatic Pressure; D007403:Intervertebral Disc / Q000378:metabolism* / Q000473:pathology; D007405:Intervertebral Disc Displacement / Q000378:metabolism* / Q000473:pathology; D037181:Lectins, C-Type; D020778:Matrix Metalloproteinase 2 / Q000235:genetics / Q000378:metabolism; D019278:Matrix Metalloproteinase 3 / Q000235:genetics / Q000378:metabolism; D010507:Periodicity; D016133:Polymerase Chain Reaction / Q000295:instrumentation*; D011509:Proteoglycans / Q000235:genetics / Q000378:metabolism; D012333:RNA, Messenger / Q000235:genetics
chemical_list: D053674:Aggrecans; D024042:Collagen Type I; D024043:Collagen Type II; D017931:DNA Primers; D016326:Extracellular Matrix Proteins; D037181:Lectins, C-Type; D011509:Proteoglycans; D012333:RNA, Messenger; D019278:Matrix Metalloproteinase 3; D020778:Matrix Metalloproteinase 2