title: Viability, growth kinetics and stem cell markers of single and clustered cells in human intervertebral discs: implications for regenerative therapies.
abstract: OBJECTIVE
  There is much interest in the development of a cellular therapy for the repair or regeneration of degenerate intervertebral discs (IVDs) utilising autologous cells, with some trials already underway. Clusters of cells are commonly found in degenerate IVDs and are formed via cell proliferation, possibly as a repair response. We investigated whether these clusters may be more suitable as a source of cells for biological repair than the single cells in the IVD.
  
  
  METHODS
  Discs were obtained at surgery from 95 patients and used to assess the cell viability, growth kinetics and stem or progenitor cell markers in both the single and clustered cell populations.
  
  
  RESULTS
  Sixty-nine percent (±15) of cells in disc tissue were viable. The clustered cell population consistently proliferated more slowly in monolayer than single cells, although this difference was only significant at P0-1 and P3-4. Both populations exhibited progenitor or notochordal cell markers [chondroitin sulphate epitopes (3B3(-), 7D4, 4C3 and 6C3), Notch-1, cytokeratin 8 and 19] via immunohistochemical examination; stem cell markers assessed with flow cytometry (CD73, 90 and 105 positivity) were similar to those seen on bone marrow-derived mesenchymal stem cells.
  
  
  CONCLUSIONS
  These results confirm those of previous studies indicating that progenitor or stem cells reside in adult human intervertebral discs. However, although the cell clusters have arisen via proliferation, there appear to be no greater incidence of these progenitor cells within clusters compared to single cells. Rather, since they proliferate more slowly in vitro than the single cell population, it may be beneficial to avoid the use of clustered cells when sourcing autologous cells for regenerative therapies.
authors.affiliation: Spinal Studies, TORCH Building, Robert Jones and Agnes Hunt Orthopaedic Hospital NHS Foundation Trust, Oswestry, Shropshire, SY10 7AG, UK, sarah.turner2@rjah.nhs.uk.
authors.forename: Sarah
authors.initials: S
authors.lastname: Turner
authors.forename: Birender
authors.initials: B
authors.lastname: Balain
authors.forename: Bruce
authors.initials: B
authors.lastname: Caterson
authors.forename: Clare
authors.initials: C
authors.lastname: Morgan
authors.forename: Sally
authors.initials: S
authors.lastname: Roberts
mesh_terms: D015720:5'-Nucleotidase / Q000378:metabolism; D000293:Adolescent; D000328:Adult; D015703:Antigens, CD / Q000378:metabolism; D015415:Biomarkers / Q000378:metabolism; D049109:Cell Proliferation; D002470:Cell Survival; D002478:Cells, Cultured; D002809:Chondroitin Sulfates / Q000378:metabolism; D000071063:Endoglin; D000939:Epitopes / Q000378:metabolism; D058851:GPI-Linked Proteins / Q000378:metabolism; D006801:Humans; D007403:Intervertebral Disc / Q000166:cytology* / Q000378:metabolism; D055959:Intervertebral Disc Degeneration / Q000378:metabolism / Q000473:pathology*; D053539:Keratin-19 / Q000378:metabolism; D053533:Keratin-8 / Q000378:metabolism; D008297:Male; D008875:Middle Aged; D051881:Receptor, Notch1 / Q000378:metabolism; D011956:Receptors, Cell Surface / Q000378:metabolism; D018800:Thy-1 Antigens / Q000378:metabolism; D055815:Young Adult
chemical_list: D015703:Antigens, CD; D015415:Biomarkers; C064206:ENG protein, human; D000071063:Endoglin; D000939:Epitopes; D058851:GPI-Linked Proteins; D053539:Keratin-19; D053533:Keratin-8; C497761:NOTCH1 protein, human; D051881:Receptor, Notch1; D011956:Receptors, Cell Surface; D018800:Thy-1 Antigens; D002809:Chondroitin Sulfates; D015720:5'-Nucleotidase; C548241:NT5E protein, human
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