title: Stem Cell Marker Expression in Persistent Apical Periodontitis.
abstract: BACKGROUND
  This study evaluated the expression of CD90 (mesenchymal stem cell) and Sox2 (progenitor stem cell) markers in persistent apical periodontitis (PAP) (n = 16) and primary periapical lesions (PPLs) (n = 10).
  
  
  METHODS
  All samples were classified histologically according to the intensity of inflammatory cell infiltrate in the periapical lesion. Immunohistochemistry was used to detect CD90 and Sox2 in PAP and PPLs. The Spearman correlation coefficient and the Mann-Whitney U test were used to analyze data at the 5% significance level.
  
  
  RESULTS
  CD90 expression was found in mesenchymal cells and vascular endothelial cells of 68.5% of all cases of PAP. There was no correlation between CD90 expression and histopathological diagnosis (P = .053) or inflammatory cell infiltrate intensity (P = .112). CD90 staining was predominantly found in the vascular endothelial cells of 30% (n = 3) of PPLs. CD90 expression was significantly higher in PAP than in PPLs (Mann-Whitney U test, P < .05). Sox2 expression was found in all cases of PAP. Eventually, all mesenchymal and chronic inflammatory cells exhibited Sox2 expression. There was no correlation between Sox2 expression and histopathological diagnoses (P = .749), inflammatory cell infiltrate intensity (P = .510), or acute or chronic inflammatory cell infiltrate (P = .256). Sox2 expression was found in 100% of PPLs. There was no difference in Sox2 expression between PAP and PPLs (P = .477).
  
  
  CONCLUSIONS
  Mesenchymal stem cells may contribute to the immunosuppressive environment in PAP. Additionally, distinct stem cell sources may be associated with the chronic nature of PAP as well as with the development of PPLs.
authors.affiliation: Department of Stomatologic Sciences, School of Dentistry, Federal University of Goiás, Goiânia, Brazil. Electronic address: estrela3@terra.com.br.
authors.forename: Carlos
authors.initials: C
authors.lastname: Estrela
authors.affiliation: Department of Stomatologic Sciences, School of Dentistry, Federal University of Goiás, Goiânia, Brazil.
authors.forename: Brunno Santos
authors.initials: BS
authors.lastname: Freitas Silva
authors.affiliation: Department of Stomatologic Sciences, School of Dentistry, Federal University of Goiás, Goiânia, Brazil.
authors.forename: Júlio A
authors.initials: JA
authors.lastname: Silva
authors.affiliation: Department of Stomatologic Sciences, School of Dentistry, Federal University of Goiás, Goiânia, Brazil.
authors.forename: Fernanda P
authors.initials: FP
authors.lastname: Yamamoto-Silva
authors.affiliation: Department of Stomatology, School of Dentistry, University of São Paulo, São Paulo, Brazil.
authors.forename: Décio Dos Santos
authors.initials: DD
authors.lastname: Pinto-Júnior
authors.affiliation: Department of Oral Surgery and Pathology, School of Dentistry, Federal University of Minas Gerais, Belo Horizonte, Brazil.
authors.forename: Ricardo Santiago
authors.initials: RS
authors.lastname: Gomez
mesh_terms: D015415:Biomarkers; D042783:Endothelial Cells / Q000378:metabolism; D059630:Mesenchymal Stem Cells / Q000378:metabolism*; D010485:Periapical Periodontitis / Q000378:metabolism* / Q000473:pathology; D010486:Periapical Tissue / Q000166:cytology / Q000378:metabolism / Q000473:pathology; D055748:SOXB1 Transcription Factors / Q000378:metabolism*; D013234:Stem Cells; D018800:Thy-1 Antigens / Q000378:metabolism*
chemical_list: D015415:Biomarkers; C527782:SOX2 protein, human; D055748:SOXB1 Transcription Factors; D018800:Thy-1 Antigens
keywords: Apical periodontitis; CD90; Sox2; mesenchymal stem cells; persistent apical periodontitis; progenitor stem cells