Mechanical stimulation alters pleiotrophin and aggrecan expression by human intervertebral disc cells and influences their capacity to stimulate endothelial migration

Cornelia Neidlinger-Wilke, Astrid Liedert, Karin Wuertz, Zorica Buser, Christina Rinkler, Wolfram Käfer, Anita Ignatius, Lutz Claes, Sally Roberts, W Eustace B Johnson

Research output: Contribution to journalArticlepeer-review

Abstract

Study Design. The influence of mechanical load on pleiotrophin (PTM) and aggrecan expression by intervertebral disc (IVD) cells, and the effects of disc cell conditioned medium on endothelial cell migration was investigated.

Objective. To examine possible interactions of mechanical loads and known pro- and antiangiogenic factors, which may regulate disc angiogenesis during degeneration.

Summary of Background Data. Pleiotrophin expression can be influenced by mechanical stimulation and has been associated with disc vascularization. Disc aggrecan inhibits endothelial cell migration, suggesting an antiangiogenic role. A possible interplay between these factors is unknown.

Methods. The influence of the respective predominant load (cyclic strain for anulus fibrosus and hydrostatic pressure for nucleus pulposus cells) on PTN and aggrecan expression by IVD cells was determined by real-time RT-PCR and Western blotting (PTN only). The effects of IVD cell conditioned medium on endothelial cell migration were analyzed in a bioassay using human microvascular endothelial (HMEC-1) cells.

Results. Application of both mechanical loads resulted in significant alterations of gene expression of PTN (+67%, P = 0.004 in anulus cells; +29%, P = 0.03 in nucleus cells) and aggrecan (+42%, P = 0.03 in anulus cells, -25%, P = 0.03 in nucleus cells). These effects depended on the cell type, the applied load, and timescale. Conditioned media of nucleus pulposus cells enhanced HMEC-1 migration, but this effect was diminished after 2.5 MPa hydrostatic pressure, when aggrecan expression was diminished, but not 0.25 MPa, when expression levels were unchanged.

Conclusion. Mechanical loading influences PTN expression by human IVD cells. Conditioned media from nucleus pulposus cell cultures stimulated HMEC-1 endothelial cell migration. This study demonstrates that the influence of mechanical loads on vascularization of the human IVD is likely to be complex and does not correlate simply with altered expression of known pro- and antiangiogenic factors.
Original languageEnglish
Pages (from-to)663-669
Number of pages7
JournalSpine
Volume34
Issue number7
DOIs
Publication statusPublished - 1 Apr 2009

Keywords

  • aggrecans
  • angiogenesis inducing agents
  • blood vessels
  • carrier proteins
  • cell communication
  • cell line
  • cell movement
  • cultured cells
  • conditioned culture media
  • cytokines
  • endothelial cells
  • humans
  • intervertebral disc
  • intervertebral disc displacement
  • cellular mechanotransduction
  • physiologic neovascularization
  • physical stimulation
  • messenger RNA
  • regeneration
  • up-regulation
  • weight-bearing

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