title: Effect of Static Load on the Nucleus Pulposus of Rabbit Intervertebral Disc Motion Segment in Ex vivo Organ Culture.
abstract: BACKGROUND
  The development of mechanically active culture systems helps increase the understanding of the role of mechanical stress in intervertebral disc (IVD) degeneration. Motion segment cultures allow for preservation of the native IVD structure, and adjacent vertebral bodies facilitate the application and control of mechanical loads. The purpose of this study was to establish loading and organ culture methods for rabbit IVD motion segments to study the effect of static load on the whole disc organ.
  
  
  METHODS
  IVD motion segments were harvested from rabbit lumbar spines and cultured in no-loading 6-well plates (control conditions) or custom-made apparatuses under a constant, compressive load (3 kg, 0.5 MPa) for up to 14 days. Tissue integrity, matrix synthesis, and the matrix gene expression profile were assessed after 3, 7, and 14 days of culturing and compared with those of fresh tissues.
  
  
  RESULTS
  The results showed that ex vivo culturing of motion segments preserved tissue integrity under no-loading conditions for 14 days whereas the static load gradually destroyed the morphology after 3 days. Proteoglycan contents were decreased under both conditions, with a more obvious decrease under static load, and proteoglycan gene expression was also downregulated. However, under static load, immunohistochemical staining intensity and collagen Type II alpha 1 (COL2A1) gene expression were significantly enhanced (61.54 ± 5.91, P = 0.035) and upregulated (1.195 ± 0.040, P = 0.000), respectively, compared with those in the controls (P < 0.05). In contrast, under constant compression, these trends were reversed. Our initial results indicated that short-term static load stimulated the synthesis of collagen Type II alpha 1; however, sustained constant compression led to progressive degeneration and specifically to a decreased proteoglycan content.
  
  
  CONCLUSIONS
  A loading and organ culture system for ex vivo rabbit IVD motion segments was developed. Using this system, we were able to study the effects of mechanical stimulation on the biology of IVDs, as well as the pathomechanics of IVD degeneration.
authors.affiliation: Spine Department 2, Wangjing Hospital, China Academy of Chinese Medical Sciences, Beijing 100102; Key Laboratory of Beijing of Palasy Technology, Wangjing Hospital, China Academy of Chinese Medical Sciences, Beijing 100102, China.
authors.forename: Li-Guo
authors.initials: LG
authors.lastname: Zhu
authors.affiliation: Spine Department 2, Wangjing Hospital, China Academy of Chinese Medical Sciences, Beijing 100102; Key Laboratory of Beijing of Palasy Technology, Wangjing Hospital, China Academy of Chinese Medical Sciences, Beijing 100102, China.
authors.forename: Min-Shan
authors.initials: MS
authors.lastname: Feng
authors.affiliation: Key Laboratory of Beijing of Palasy Technology, Wangjing Hospital, China Academy of Chinese Medical Sciences, Beijing 100102; General Orthopedics Department, Wangjing Hospital, China Academy of Chinese Medical Sciences, Beijing 100102, China.
authors.forename: Jia-Wen
authors.initials: JW
authors.lastname: Zhan
authors.affiliation: Department of Pathology, Wangjing Hospital, China Academy of Chinese Medical Sciences, Beijing 100102, China.
authors.forename: Ping
authors.initials: P
authors.lastname: Zhang
authors.affiliation: Spine Department 2, Wangjing Hospital, China Academy of Chinese Medical Sciences, Beijing 100102, China.
authors.forename: Jie
authors.initials: J
authors.lastname: Yu
mesh_terms: D000818:Animals; D005786:Gene Expression Regulation; D007150:Immunohistochemistry; D007403:Intervertebral Disc / Q000378:metabolism* / Q000502:physiology*; D055959:Intervertebral Disc Degeneration / Q000378:metabolism / Q000503:physiopathology; D008297:Male; D000070614:Nucleus Pulposus / Q000378:metabolism* / Q000502:physiology*; D009924:Organ Culture Techniques / Q000379:methods*; D011817:Rabbits; D013314:Stress, Mechanical