The gingiva is renowned for its rapid, scar-free healing, a phenomenon linked to the unique properties of its fibroblasts. Foundational studies have highlighted significant intra- and inter-tissue heterogeneity among fibroblasts. We, alongside others, demonstrated discrepancies between gingival and skin fibroblasts. Yet, a comprehensive understanding of these differences, especially in a human context, remains underexplored.

This study examines the subpopulations of human gingival and skin fibroblasts to uncover the molecular and functional heterogeneity underlying their divergent healing outcomes.

We investigated fibroblast heterogeneity through scRNA-seq of skin and gingival tissue. These data were enriched with our lab’s bulk RNA-seq results and RNA-seq data from regenerative species, used as a gene screening tool for specific tissue subpopulations.

We identified nine distinct fibroblast clusters, three specific to gingiva and three to skin. Pseudotime analysis revealed shared clusters between the two tissues that subsequently differentiate into distinct skin- or gingiva-specific subpopulations. Gingival fibroblasts exhibited markers associated with immune cell recruitment, early wound healing, and extracellular matrix organization. Skin clusters were linked to innate immune cell recruitment, elastic fiber formation, and keratinization. Notably, one skin cluster displayed markers for reticular fibroblasts, associated with fibrotic healing, while papillary fibroblasts, known for promoting scar-free repair were more broadly represented.

Moreover, comparing gingiva-specific markers with extracellular matrix genes from regenerative species such as axolotls and Acomys mice highlighted several genes linked to ad integrum healing. Cross-referencing these markers with Mendelian genes involved in genetic oral disorders also identified genes associated with mucosal healing anomalies.

This study reveals distinct molecular signatures and functional differences between human gingival and skin fibroblast subpopulations, shedding light on the unique pathways contributing to scar-free healing in gingiva. The identification of gingiva-specific markers linked to regenerative-associated genes offers promising insights for developing therapeutic approaches to enhance scar-free healing in other tissues.