title: The chemokines CXCL10 and XCL1 recruit human annulus fibrosus cells.
abstract: METHODS
  Human annulus fibrosus tissue and cells were analyzed for the presence of chemokine receptors and the migratory effect of selected chemokines.
  
  
  OBJECTIVE
  To investigate spontaneous repair mechanisms and underlying cell recruitment in response to annular tears and degenerative defects.
  
  
  BACKGROUND
  Resorption of herniated disc tissue and the attempt to close annulus tears with repair tissue occur spontaneously. Although chemokines are suggested to play a role in resorption of herniated disc tissue, the role of chemokines in annulus fibrosus homeostasis and repair remains unclear.
  
  
  METHODS
  Cells were isolated from annulus fibrosus tissue and expanded in the presence of human serum. Multiwell chemotaxis assays were used to analyze the migratory effect of human serum and 0 to 1000 nM concentrations of the chemokines CXCL7, CXCL10, CXCL12, CCL25, and XCL1 on annulus fibrosus cells (AFCs) (n = 9 per chemokine and dose). Presence of corresponding chemokine receptors in AFCs was determined by real-time polymerase chain reaction analysis and immunohistochemistry.
  
  
  RESULTS
  Serum (0.1%-10%) significantly (P < 0.01) stimulates the migration of AFCs. Compared with untreated cells, the migration of cells was significantly (P < 0.01) enhanced upon stimulation with 100 to 1000 nM CXCL10 and 1000 nM XCL1. Chemokine receptors showed low expression levels in expanded AFCs as assessed by polymerase chain reaction. Immunohistochemical staining of the CXCL10 receptor CXCR3 and the XCL1 receptor XCR1 showed that the presence of the particular receptors in AFCs expanded under conventional cell culture conditions. In native annulus fibrosus tissue, CXCR3 was evident, whereas XCR1 could not be detected.
  
  
  CONCLUSIONS
  The findings suggest that chemokines, in particular CXCL10, effectively recruit isolated AFCs. This suggests that chemokines are involved in annulus fibrosus homeostasis and potentially in spontaneous annulus repair attempts. This might have important implications for biological annulus-sealing strategies.
authors.affiliation: Department of Neurosurgery, Universitätsmedizin Mannheim, University of Heidelberg, Mannheim, Germany.
authors.forename: Aldemar A
authors.initials: AA
authors.lastname: Hegewald
authors.forename: Katja
authors.initials: K
authors.lastname: Neumann
authors.forename: Gregor
authors.initials: G
authors.lastname: Kalwitz
authors.forename: Undine
authors.initials: U
authors.lastname: Freymann
authors.forename: Michaela
authors.initials: M
authors.lastname: Endres
authors.forename: Kirsten
authors.initials: K
authors.lastname: Schmieder
authors.forename: Christian
authors.initials: C
authors.lastname: Kaps
authors.forename: Claudius
authors.initials: C
authors.lastname: Thomé
mesh_terms: D000328:Adult; D000368:Aged; D018929:Cell Culture Techniques / Q000379:methods; D002478:Cells, Cultured; D054357:Chemokine CXCL10 / Q000494:pharmacology / Q000502:physiology*; D019744:Chemokines, C / Q000494:pharmacology / Q000502:physiology*; D002633:Chemotaxis / Q000187:drug effects / Q000502:physiology*; D005260:Female; D005347:Fibroblasts / Q000187:drug effects / Q000502:physiology*; D051445:Fibrocartilage / Q000166:cytology* / Q000502:physiology; D006801:Humans; D007403:Intervertebral Disc / Q000166:cytology* / Q000502:physiology; D008297:Male; D008875:Middle Aged
chemical_list: C114753:CXCL10 protein, human; D054357:Chemokine CXCL10; D019744:Chemokines, C; C092390:XCL1 protein, human