title: Pre-existing root cementum may promote cementoblast differentiation of human periodontal ligament cells.
abstract: OBJECTIVE
  To observe whether preserved healthy cementum could promote differentiation of human periodontal ligament cells to cementoblasts.
  
  
  METHODS
  Symmetrical root slices from each healthy premolar were distributed into either the control group (cementum removed) or test group (cementum preserved). After isolation and characterization, human periodontal ligament cells were inoculated onto root slices for 7 days co-culture. Two slices per group were studied for cell morphology by scanning electronic microscopy. Twenty-three slices were detected for expression of cementum attachment protein and cementum protein 23, two putative cementoblast markers, by real-time polymerase chain reaction. Twenty slices were transplanted into nude mice and analysed using histology and immunohistochemistry for osteopontin and bone sialoprotein expression after 8 weeks.
  
  
  RESULTS
  Cells of the test group had smoother fibroblast morphology and higher cementum protein 23 and cementum attachment protein expression than those of the control group (P < 0.01). In the test group, 14 root slices revealed cementum-like matrix formation resting on old cementum; no splits were observed between newly formed matrix and old cementum. In the control group, 17 specimens had fibrous tissue formation along the root surface and varying width of splits could be seen between new fibrous tissue and dentine surface. Only three specimens demonstrated presence of newly formed thin cementum-like matrix. Newly formed cementum-like matrix was positive for osteopontin and bone sialoprotein.
  
  
  CONCLUSIONS
  The results demonstrate that healthy root cementum may promote differentiation of human periodontal ligament cells towards cementoblasts.
authors.affiliation: Department of Periodontology, School of Stomatology, Shandong University, Jinan, China.
authors.forename: A
authors.initials: A
authors.lastname: Song
authors.forename: J
authors.initials: J
authors.lastname: Cai
authors.forename: K
authors.initials: K
authors.lastname: Pan
authors.forename: P
authors.initials: P
authors.lastname: Yang
mesh_terms: D000818:Animals; D002454:Cell Differentiation; D002478:Cells, Cultured; D018920:Coculture Techniques; D003739:Dental Cementum / Q000378:metabolism* / Q000473:pathology; D003804:Dentin / Q000378:metabolism / Q000473:pathology; D006801:Humans; D051379:Mice; D008819:Mice, Nude; D010513:Periodontal Ligament / Q000166:cytology* / Q000378:metabolism; D017027:Protein Tyrosine Phosphatases / Q000378:metabolism; D011506:Proteins / Q000378:metabolism; D013234:Stem Cells / Q000166:cytology; D014092:Tooth Root / Q000473:pathology
chemical_list: C510886:CEMP1 protein, human; D011506:Proteins; C404489:HACD1 protein, human; D017027:Protein Tyrosine Phosphatases