Stem Cell Marker Expression in Persistent Apical Periodontitis

Abstract Introduction 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 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.