Immunohistochemical identification of MMP-2 and MMP-9 in human dentin: correlative FEI-SEM/TEM analysis.
Matrix metalloproteinases (MMPs) are a family of peptidases trapped within mineralized dentin matrix and involved with degradation of the extracellular matrix components in hybrid layers and caries. Despite their identification through indirect evidences and biochemical assays, MMP-2 and -9 have not been localized within the human dentin extracellular organic matrix. Thus, this study aimed to assess the localization and distribution of MMP-2 and -9 in human dentin organic matrix by employing a correlative field emission in-lens-scanning electron microscopy (FEI-SEM) and transmission electron microscopy (TEM) immunohistochemical approach. Dentin specimens were submitted either to a preembedding or to a postembedding immunolabeling technique using primary monoclonal antibodies anti-MMP-2 and anti-MMP-9 and exposed to a secondary antibody conjugated with gold nanoparticles. MMP-2 and -9 labelings were identified in the demineralized dentin matrix as highly electron-dense gold particles dispersed on the collagen fibrils. Correlative FEI-SEM/TEM observations confirmed that MMP-2 and MMP-9 are endogenous components of the human dentin organic matrix and revealed the three-dimensional relationship between these proteinases and the collagen fibrils, showing that both antibodies yielded a similar labeling pattern. In conclusion, the results of the study contribute to reveal distinct distribution pattern of gelatinases and support the hypothesis that these enzymes are intrinsic constituents of the dentin organic matrix after decalcification.
Mazzoni
Annalisa
A
Department of SAU and FAL, University of Bologna, Bologna, Italy.
Pashley
David H
DH
Tay
Franklin R
FR
Gobbi
Pietro
P
Orsini
Giovanna
G
Ruggeri
Alessandra
A
Carrilho
Marcela
M
Tjäderhane
Leo
L
Di Lenarda
Roberto
R
Breschi
Lorenzo
L
D000328:Adult; D003804:Dentin / Q000201:enzymology* / Q000276:immunology / Q000648:ultrastructure*; D006801:Humans; D007150:Immunohistochemistry / Q000379:methods*; D020778:Matrix Metalloproteinase 2 / Q000032:analysis* / Q000276:immunology / Q000378:metabolism*; D020780:Matrix Metalloproteinase 9 / Q000032:analysis* / Q000276:immunology / Q000378:metabolism*; D008855:Microscopy, Electron, Scanning; D046529:Microscopy, Electron, Transmission
D020778:Matrix Metalloproteinase 2; D020780:Matrix Metalloproteinase 9