title: The effect of hydrostatic pressure on intervertebral disc metabolism.
abstract: METHODS
  By the use of pressure vessels, hydrostatic pressure was applied to intervertebral disc cells cultured in an alginate.
  
  
  OBJECTIVE
  To test the hypothesis that hydrostatic pressure directly affects the synthesis of collagen and proteoglycan by the intervertebral disc cells.
  
  
  BACKGROUND
  The influence of compression (both hydrostatic and mechanical) on chondrocyte metabolism was examined in a number of earlier studies. However, in most of these studies, articular cartilage, not intervertebral disc, was used, and in none of these was hydrostatic pressure applied to intervertebral disc cells cultured in alginate.
  
  
  METHODS
  Fresh cells were harvested from the lumbar intervertebral discs of dogs. Before their suspension in an alginate gel system, the cells were plated and expanded until they reached confluence. Then, by use of the alginate gel system, the cells were exposed (for up to 9 days) to specific values of hydrostatic pressure inside two stainless steel pressure vessels. One vessel was kept at 1 MPa and the other at atmospheric pressure. The effects of 1 MPa were compared against atmospheric pressure by measuring the incorporation of [3H]-proline and [35S]-sulfate into collagen and proteoglycans, respectively, for the anulus cells and nucleus cells separately, and by determining whether this incorporation was reflected by changes in the levels of mRNA for aggrecan and Types I and II collagen.
  
  
  RESULTS
  Comparisons with atmospheric pressure yielded the following findings: 1) In the incorporation studies, the nucleus and anulus cells exhibited a differential response to a hydrostatic pressure of 1 MPa. Collagen and proteoglycan syntheses were stimulated in the nucleus cells and inhibited in the anulus cells. 2) There was no significant increase in cell proliferation, as measured by DNA content, at 1 MPa for either the anulus or nucleus cells. 3) The mRNA levels of collagen (Col 1A1 and Col 2A1) and aggrecan increased at 1 MPa in both the nucleus and anulus cells.
  
  
  CONCLUSIONS
  Hydrostatic pressure directly affects the synthesis of collagen and proteoglycan by the intervertebral disc cells.
authors.affiliation: Department of Orthopaedics, Emory University School of Medicine, Atlanta, Georgia, USA.
authors.forename: W C
authors.initials: WC
authors.lastname: Hutton
authors.forename: W A
authors.initials: WA
authors.lastname: Elmer
authors.forename: S D
authors.initials: SD
authors.lastname: Boden
authors.forename: S
authors.initials: S
authors.lastname: Hyon
authors.forename: Y
authors.initials: Y
authors.lastname: Toribatake
authors.forename: K
authors.initials: K
authors.lastname: Tomita
authors.forename: G A
authors.initials: GA
authors.lastname: Hair
mesh_terms: D053674:Aggrecans; D000464:Alginates; D000818:Animals; D002478:Cells, Cultured; D011508:Chondroitin Sulfate Proteoglycans / Q000096:biosynthesis; D003094:Collagen / Q000096:biosynthesis; D004285:Dogs; D016326:Extracellular Matrix Proteins; D020723:Glucuronic Acid; D006603:Hexuronic Acids; D006874:Hydrostatic Pressure; D066298:In Vitro Techniques; D007403:Intervertebral Disc / Q000378:metabolism*; D037181:Lectins, C-Type; D008159:Lumbar Vertebrae; D011509:Proteoglycans / Q000096:biosynthesis
chemical_list: D053674:Aggrecans; D000464:Alginates; D011508:Chondroitin Sulfate Proteoglycans; D016326:Extracellular Matrix Proteins; D006603:Hexuronic Acids; D037181:Lectins, C-Type; D011509:Proteoglycans; D020723:Glucuronic Acid; D003094:Collagen