title: Multipotential differentiation of human anulus fibrosus cells: an in vitro study.
abstract: BACKGROUND
  The existence of fibrocartilage, bone-like tissues, nerves, and blood vessels in the anulus fibrosus during intervertebral disc degeneration has been well documented. Migration of differentiated cells from outside the intervertebral disc has been hypothesized as a possible mechanism for the formation of these tissues. We hypothesized that the normal anulus fibrosus tissue contains multipotent progenitor cells, which are able to differentiate into cartilage and/or fibrocartilage cells, osteoblasts, neurons, and blood vessel cells.
  
  
  METHODS
  We isolated anulus fibrosus cells from the nondegenerative intervertebral discs of adolescent (thirteen to sixteen-year-old) patients with idiopathic scoliosis and cultured the cells in vitro in induction media containing different stimuli. Immunophenotypic analysis of cell surface markers was performed by flow cytometry. Expression of markers of adipogenesis, osteogenesis, chondrogenesis, neurogenesis, and differentiation into endothelial lineages was determined with use of immunostaining, cytohistological staining, and reverse transcription-polymerase chain reaction.
  
  
  RESULTS
  Anulus fibrosus cells expressed several of the cell surface antigens that are sometimes associated with mesenchymal stem cells, including CD29, CD49e, CD51, CD73, CD90, CD105, CD166, CD184, and Stro-1, and two neuronal stem cell markers, nestin and neuron-specific enolase. Furthermore, varying the stimulants added to the induction media determined whether anulus fibrosus cells differentiated into adipocytes, osteoblasts, chondrocytes, neurons, or endothelial cells.
  
  
  CONCLUSIONS
  Anulus fibrosus cells isolated from nondegenerative intervertebral discs can differentiate into adipocytes, osteoblasts, chondrocytes, neurons, and endothelial cells in vitro.
authors.affiliation: Department of Orthopaedic Surgery, Nanchong Central Hospital, North Sichuan Medical College, Nanchong 637000, PR China.
authors.forename: Gang
authors.initials: G
authors.lastname: Feng
authors.forename: Xinlin
authors.initials: X
authors.lastname: Yang
authors.forename: Hulan
authors.initials: H
authors.lastname: Shang
authors.forename: Ian W
authors.initials: IW
authors.lastname: Marks
authors.forename: Francis H
authors.initials: FH
authors.lastname: Shen
authors.forename: Adam
authors.initials: A
authors.lastname: Katz
authors.forename: Vincent
authors.initials: V
authors.lastname: Arlet
authors.forename: Cato T
authors.initials: CT
authors.lastname: Laurencin
authors.forename: Xudong
authors.initials: X
authors.lastname: Li
mesh_terms: D000293:Adolescent; D000704:Analysis of Variance; D015703:Antigens, CD / Q000378:metabolism; D015415:Biomarkers / Q000378:metabolism; D002454:Cell Differentiation; D002478:Cells, Cultured; D005260:Female; D005434:Flow Cytometry; D006801:Humans; D016130:Immunophenotyping; D066298:In Vitro Techniques; D007403:Intervertebral Disc / Q000166:cytology* / Q000378:metabolism / Q000473:pathology; D008297:Male; D020133:Reverse Transcriptase Polymerase Chain Reaction; D012600:Scoliosis / Q000378:metabolism / Q000473:pathology; D013194:Staining and Labeling
chemical_list: D015703:Antigens, CD; D015415:Biomarkers