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.