Single-cell transcriptomic analysis of oral masticatory and lining mucosa-derived mesenchymal stromal cells.

AIM: To reveal the heterogeneity of ex vivo-cultured human mesenchymal stromal cells derived from either masticatory or lining oral mucosa. MATERIALS AND METHODS: Cells were retrieved from the lamina propria of the hard palate and alveolar mucosa of three individuals. The analysis of transcriptomic-level differences was accomplished using single-cell RNA sequencing. RESULTS: Cluster analysis clearly distinguished between cells from the masticatory and lining oral mucosa, and revealed 11 distinct cell sub-populations, annotated as fibroblasts, smooth muscle cells or mesenchymal stem cells. Interestingly, cells presenting a mesenchymal stem cell-like gene expression pattern were predominantly found in masticatory mucosa. Although cells of masticatory mucosa origin were highly enriched for biological processes associated with wound healing, those from the lining oral mucosa were highly enriched for biological processes associated with the regulation of epithelial cells. CONCLUSIONS: Our previous work had shown that cells from the lining and masticatory oral mucosae are phenotypically heterogeneous. Here, we extend these findings to show that these changes are not the result of differences in averages but rather represent two distinct cell populations, with mesenchymal stem cells more common in masticatory mucosa. These features may contribute to specific physiological functions and have relevance for potential therapeutic interventions.

Fibroblasts from the oral masticatory and lining mucosa have different gene expression profiles and proliferation rates.

AIMS: To compare the gene expression profiles and proliferation rates of fibroblasts from the oral lining and masticatory mucosae. MATERIALS AND METHODS: Primary human fibroblasts were retrieved from the posterior masticatory hard palate and the lining alveolar mucosa of five individuals. The gene expression profile was evaluated using total RNA sequencing. The proliferation rate was determined colorimetrically. RESULTS: Substantial differences in specific gene groups and pathways were observed between fibroblasts from the two tissues. Significantly enriched gene ontology processes were focused on the extracellular components. Lining mucosa fibroblasts exhibited significantly higher expression of the principal structural collagens, cranial neural crest markers, and homeobox genes associated with positional memory. Masticatory mucosa fibroblasts showed greater expression of genes related to transforming growth factor-ß signalling, which may be associated with fibrosis. In addition, they expressed higher levels of the EP2 prostaglandin E2 receptor and Toll-like receptor 1. Finally, masticatory mucosa fibroblasts exhibited a 10%-30% higher proliferation rate. CONCLUSIONS: Fibroblasts from the lining and masticatory oral mucosae are phenotypically heterogeneous, presenting distinct gene expression profiles and proliferation rates. These features may contribute to their specific physiological functions and have relevance for potential therapeutic applications.