title: Immortalization and characterization of mouse temporomandibular joint disc cell clones with capacity for multi-lineage differentiation.
abstract: OBJECTIVE
  Despite the importance of temporomandibular joint (TMJ) disc in normal function and disease, studying the responses of its cells has been complicated by the lack of adequate characterization of the cell subtypes. The purpose of our investigation was to immortalize, clone, characterize and determine the multi-lineage potential of mouse TMJ disc cells.
  
  
  METHODS
  Cells from 12-week-old female mice were cultured and immortalized by stable transfection with human telomerase reverse transcriptase (hTERT). The immortalized cell clones were phenotyped for fibroblast- or chondrocyte-like characteristics and ability to undergo adipocytic, osteoblastic and chondrocytic differentiation.
  
  
  RESULTS
  Of 36 isolated clones, four demonstrated successful immortalization and maintenance of stable protein expression for up to 50 passages. Two clones each were initially characterized as fibroblast-like and chondrocyte-like on the basis of cell morphology and growth rate. Further the chondrocyte-like clones had higher mRNA expression levels of cartilage oligomeric matrix protein (COMP) (>3.5-fold), collagen X (>11-fold), collagen II expression (2-fold) and collagen II:I ratio than the fibroblast-like clones. In contrast, the fibroblast-like clones had higher mRNA expression level of vimentin (>1.5-fold), and fibroblastic specific protein 1 (>2.5-fold) than the chondrocyte-like clones. Both cell types retained multi-lineage potential as demonstrated by their capacity to undergo robust adipogenic, osteogenic and chondrogenic differentiation.
  
  
  CONCLUSIONS
  These studies are the first to immortalize TMJ disc cells and characterize chondrocyte-like and fibroblast-like clones with retained multi-differentiation potential that would be a valuable resource in studies to dissect the behavior of specific cell types in health and disease and for tissue engineering.
authors.affiliation: Department of Orthodontics and Pediatric Dentistry, School of Dentistry, The University of Michigan, Ann Arbor, MI, USA.
authors.forename: Y
authors.initials: Y
authors.lastname: Park
authors.affiliation: Department of Orthodontics and Pediatric Dentistry, School of Dentistry, The University of Michigan, Ann Arbor, MI, USA; Department of Orthodontic Science, Graduate School, Tokyo Medical and Dental University, Tokyo, Japan.
authors.forename: J
authors.initials: J
authors.lastname: Hosomichi
authors.affiliation: Department of Periodontics and Oral Medicine, School of Dentistry, The University of Michigan, Ann Arbor, MI, USA.
authors.forename: C
authors.initials: C
authors.lastname: Ge
authors.affiliation: Department of Orthodontics and Pediatric Dentistry, School of Dentistry, The University of Michigan, Ann Arbor, MI, USA.
authors.forename: J
authors.initials: J
authors.lastname: Xu
authors.affiliation: Department of Periodontics and Oral Medicine, School of Dentistry, The University of Michigan, Ann Arbor, MI, USA.
authors.forename: R
authors.initials: R
authors.lastname: Franceschi
authors.affiliation: Department of Orthodontics and Pediatric Dentistry, School of Dentistry, The University of Michigan, Ann Arbor, MI, USA. Electronic address: skapila@umich.edu.
authors.forename: S
authors.initials: S
authors.lastname: Kapila
mesh_terms: D000818:Animals; D015153:Blotting, Western; D064236:Cartilage Oligomeric Matrix Protein / Q000032:analysis; D002454:Cell Differentiation; D002460:Cell Line; D002999:Clone Cells; D005260:Female; D051445:Fibrocartilage / Q000502:physiology; D006801:Humans; D007150:Immunohistochemistry; D008592:Menisci, Tibial / Q000166:cytology; D051379:Mice; D010641:Phenotype; D016133:Polymerase Chain Reaction; D011506:Proteins / Q000032:analysis; D012313:RNA / Q000032:analysis; D012333:RNA, Messenger / Q000032:analysis; D019098:Telomerase / Q000502:physiology; D019224:Temporomandibular Joint Disc / Q000166:cytology*; D014162:Transfection; D014746:Vimentin / Q000235:genetics
chemical_list: D064236:Cartilage Oligomeric Matrix Protein; D011506:Proteins; D012333:RNA, Messenger; D014746:Vimentin; D012313:RNA; D019098:Telomerase
keywords: Chondrocyte-like cell clones; Fibroblast-like cell clones; Fibrocartilage cells; Immortalization; Multi-lineage potential; TMJ disc