Distribution and synthesis of elastin in porcine gingiva and alveolar mucosa.

Histologically, there are variations in the distribution of the types of elastic fibers within the tissues of the masticatory mucosa. For example, the alveolar mucosa has heavy deposits of elastin which decrease in quantity and size as it merges with the attached gingiva. These differences in elastin content may result from the tissues' different physiological workload modulating the expression of tropoelastin mRNA. Alternatively, these differences could be due to the presence of phenotypically different fibroblasts that have different basal levels of tropoelastin mRNA expression. The aim of this study was to determine whether the differences in the distribution of elastin between alveolar mucosa and attached gingiva could be due to phenotypic differences between fibroblasts derived from these tissues. Histochemical (Miller's elastin stain) and immunohistochemical staining were used to localize elastin within these tissues. Elastin production by cultured fibroblasts derived from alveolar mucosa and attached gingiva was assessed by Western blot analyses, and Northern blot analyses were used to detect levels of elastin mRNA by these cells. The results from this study have confirmed that elastin is richly expressed in oral mucosa and poorly expressed in attached gingiva. In vitro, the cells demonstrated a capacity to synthesize and secrete tropoelastin, however this was not found to differ between cells from the two different sources. These findings indicate that while some heterogeneity in fibroblast populations may exist within various tissues of the periodontium, other factors, such as functional requirements of the tissues in which they reside, may also play an important role in the phenotypic expression of these cells.