title: Identification of cell proliferation zones, progenitor cells and a potential stem cell niche in the intervertebral disc region: a study in four species.
abstract: METHODS
  Descriptive experimental study in 4 different mammals.
  
  
  OBJECTIVE
  To investigate cell proliferation/regeneration and localize stem cells/progenitor cells within the intervertebral disc (IVD).
  
  
  BACKGROUND
  Disc degeneration (DD) is believed to play a major role in patients with chronic lumbar pain. Lately, biologic treatment options for DD have gained increasing interest. Normal regeneration processes within the IVD and have previously been sparsely described and therefore it is of great interest to increase the knowledge about these processes. Methods. Detection of cell proliferations zones and label-retaining cells were done by in vivo 5-bromo-2-deoxyuridine (BrdU) labeling in 18 rabbits, killed after 4, 6, 10, 14, 28, or 56 days. Results were visualized with immunohistochemistry and fluorescence/confocal microscopy. Localization of progenitor cell were further investigated by immunohistochemistry using antibodies towards Notch1, Delta4, Jagged1, C-KIT, KI67, and Stro-1 in normal IVD from rabbits (n = 3), rats (n = 2), minipigs (n = 2), and in human degenerated IVD (n = 4). Further, flowcytometry analysis using progenitor markers were performed on additional human IVD cells (n = 3).
  
  
  RESULTS
  BrdU positive cells were found in comparable numbers at early and late time points in most regions of the anulus fibrosus (AF) and nucleus pulposus demonstrating slow ongoing cell proliferation. In the AF border to ligament zone (AFo) and the perichondrium region (P) a stem cell niche-like pattern was determined (a high number of BrdU positive cells at early time points vs. only a few label retaining cells at later time points). In normal and DD tissue from the 4 investigated species progenitor cell markers were detected. Conclusion. The IVD is a tissue with ongoing slow cell proliferation both in the AF and the nucleus pulposus. The stem cell niche pattern detected in AFo and P can be suggested to play a role for IVD morphology and function. These findings may be of importance for the development of biologic treatment strategies.
authors.affiliation: Department of Clinical Chemistry and Transfusion Medicine, The Institute of Biomedicine, The Sahlgrenska Academy, Gothenburg University, Gothenburg, Sweden.
authors.forename: Helena
authors.initials: H
authors.lastname: Henriksson
authors.forename: Maria
authors.initials: M
authors.lastname: Thornemo
authors.forename: Camilla
authors.initials: C
authors.lastname: Karlsson
authors.forename: Olle
authors.initials: O
authors.lastname: Hägg
authors.forename: Katarina
authors.initials: K
authors.lastname: Junevik
authors.forename: Anders
authors.initials: A
authors.lastname: Lindahl
authors.forename: Helena
authors.initials: H
authors.lastname: Brisby
mesh_terms: D000328:Adult; D000818:Animals; D015415:Biomarkers / Q000378:metabolism; D049109:Cell Proliferation; D005260:Female; D005434:Flow Cytometry; D006132:Growth Plate / Q000033:anatomy & histology / Q000166:cytology; D006801:Humans; D007150:Immunohistochemistry; D007403:Intervertebral Disc / Q000033:anatomy & histology* / Q000166:cytology / Q000378:metabolism / Q000473:pathology; D055959:Intervertebral Disc Degeneration / Q000378:metabolism / Q000473:pathology; D008875:Middle Aged; D011817:Rabbits; D051381:Rats; D055153:Stem Cell Niche; D013234:Stem Cells / Q000166:cytology*
chemical_list: D015415:Biomarkers