In vitro immunoexpression of extracellular matrix proteins in dental pulpal and gingival human fibroblasts

AIM: To compare the expression of extracellular matrix (ECM) components in human pulpal and gingival fibroblasts in vitro. METHODOLOGY: Cultured dental pulp fibroblasts and gingival mucosa fibroblasts were used. Tenascin (TN), fibronectin (FN), type I (col I) and III collagen (col III) and osteonectin (ONEC) were detected by immunofluorescence. Main morphological characteristics were also analysed by light microscopy (LM) and transmission electron microscopy. RESULTS: The results revealed different expression patterns of the proteins. TN and ONEC were only immunoexpressed by pulpal fibroblast cells, suggesting a role of these glycoproteins in formation of mineralized tissues. FN and col I were present in the cytoplasms of both cell types. No expression of col III was detected. Different morphological characteristics were visualized under LM, in which pulpal fibroblasts were spindle-shaped with a wide cytoplasm, while gingival fibroblast cells exhibited stellate/pyramidal configuration, with rounded nuclei. However, ultrastructurally, both cell lineages showed very well developed rough endoplasmatic reticulum and Golgi complex. CONCLUSIONS: Due to the immunodetection of TN and ONEC on pulpal fibroblasts, the present findings demonstrated that a pulpal fibroblast cell is similar to an osteoblastic cell rather than an undifferentiated mesenchymal cell, such as a gingival fibroblast cell. Functional differences between the two cell lines may then be suggested.