Molecular interactions between human cartilaginous endplates and nucleus pulposus cells: a preliminary investigation.
METHODS
Conditioned media (CM) of cartilaginous endplates (CEPs) of intervertebral discs were analyzed in a bioassay with regard to their influence on matrix turnover and inflammatory factors on nucleus pulposus (NP) cells of the same patient. CEP tissue underwent further histological and ultrastructural analysis.


OBJECTIVE
To identify possible interactions between the CEP and the disc via molecular factors that may influence disc matrix degradation and to determine degenerative changes of CEP tissue.


BACKGROUND
Impaired endplate perme-ability due to degeneration and calcification is considered to be a key contributor to disc degeneration. An upregulation of metalloproteinases and inflammatory cytokines has been observed in degenerated intervertebral discs. Possibly, the CEP contributes to the regulation of disc matrix degradation via molecular interactions with the disc tissue.


METHODS
CEP and NP cells from the same patients (n = 6) were investigated in a bioassay with regard to their influence on matrix turnover and inflammatory factors. We determined gene expression of NP cells in alginate beads that were exposed to CM of CEP punches (CEP-CM) from the same patients. The CEP-CMs were analyzed by protein array for inflammatory cytokines. Further CEP samples underwent histological (n = 15) and ultrastructural analysis (n = 8) to determine alterations of cell and matrix structure.


RESULTS
NP cells exposed to their donor-corresponding CEP-CM significantly upregulated interleukins (IL-6, IL-8) and matrix metalloproteinase (MMP-3, MMP-13) expression, and significantly decreased aggrecan and collagen type 2 expression. Proinflammatory cytokines were identified in the CEP-CM. The occurrence of apoptotic cells and degraded matrix fragments varied strongly between donors.


CONCLUSIONS
Our results indicate interactions between the CEP and the NP tissue via molecular factors that upregulate matrix degrading enzymes and inflammatory cytokines and thereby influence the pathophysiology of disc degeneration. Ongoing investigations will further identify the regulative role of potential molecular factors that are responsible for these degenerative alterations.


METHODS
N/A.
*Institute of Orthopaedic Research and Biomechanics, Centre of Musculoskeletal Research, University of Ulm, Ulm, Baden-Württemberg, Germany †REPAIR-lab, Institute of Pathology, University of Mainz, Germany ‡Istituto Ortopedico Galeazzi, Milano, Italy §Klinik fur Orthopadie und Unfallchirurgie, Baden-Baden, Germany ¶Galenus-Klinik Stuttgart ∥Department of Orthopaedic Trauma, Hand Plastic and Reconstruction Surgery, Centre of Musculoskeletal Research, University of Ulm, Ulm, Baden-Wurttemberg, Germany; and **National Center for Spinal Disorders, Budapest, Hungary.
Cornelia
C
Neidlinger-Wilke
Antje
A
Boldt
Christoph
C
Brochhausen
Fabio
F
Galbusera
Claus
C
Carstens
Franz
F
Copf
Markus
M
Schultheiss
Aron
A
Lazary
Marco
M
Brayda-Bruno
Anita
A
Ignatius
Hans-Joachim
HJ
Wilke
D000328:Adult; D000368:Aged; D053674:Aggrecans / Q000378:metabolism; D002356:Cartilage / Q000378:metabolism*; D002478:Cells, Cultured; D005260:Female; D006801:Humans; D015850:Interleukin-6 / Q000378:metabolism; D016209:Interleukin-8 / Q000378:metabolism; D007403:Intervertebral Disc / Q000378:metabolism* / Q000473:pathology; D055959:Intervertebral Disc Degeneration / Q000378:metabolism*; D008297:Male; D053509:Matrix Metalloproteinase 13 / Q000378:metabolism; D019278:Matrix Metalloproteinase 3 / Q000378:metabolism; D008875:Middle Aged
D053674:Aggrecans; C508606:CXCL8 protein, human; C508600:IL6 protein, human; D015850:Interleukin-6; D016209:Interleukin-8; C507079:MMP13 protein, human; D053509:Matrix Metalloproteinase 13; C511768:MMP3 protein, human; D019278:Matrix Metalloproteinase 3