PROJECT SUMMARY Oral wound healing is characterized by rapid resolution of inflammation and minimal scarring. As it is a prime example of ideal tissue regeneration, there is a growing interdisciplinary interest in studying the mechanisms of oral wound healing. Fibroblasts play an essential role in this process and are also implicated in oral diseases responsible for the global economic burden amounting to 442 billion dollars. Recent advances in connective tissue biology have elucidated the importance of fibroblast heterogeneity in the pathogenesis of dermal fibrosis and rheumatoid arthritis. However, the in vivo heterogeneity of oral fibroblasts and thereby a functional significance of select fibroblast population during oral wound healing is poorly understood. Here, we found that postnatal Prx1+ cells are found in mouse gingiva and express common markers of fibroblasts. Preliminary data demonstrate that wounds enriched in Prx1+ cells heal faster with minimal inflammation compared to wounds that lack these cells. Therefore we will test the overall hypothesis that Prx1+ cells represent distinct oral fibroblast progenitors and are responsible for rapid tissue regeneration through a mechanism that involves resolution of inflammation. Aim 1 will utilize an auto-transplantation approach and test the hypothesis that transplanted Prx1+ cells contribute to accelerated oral wound healing by functioning as mesenchymal progenitors in vivo. Aim 2 will investigate if lineage specific ablation of Prx1+ cells delays wound healing by causing the failure to quickly resolve inflammation in vivo, and explore mechanisms of immune cell modulation by Prx1+ fibroblasts in co- culture assays. In Aim 3, we will perform single cell RNA-sequencing to compare transcriptomic profiles of mesenchymal and leukocyte cell subtypes in Prx1+ enriched oral wounds to those in Prx1-poor wounds in mice. Moreover, we will test if Prx1-equivalent cells are found in human gingiva by single cell sequencing and in situ validation. Upon completion, the proposed studies are expected to reveal Prx1+ cells as pro-healing oral fibroblast subset and provide a significant translational value by implicating the clinical utilization of connective tissues or ex vivo stem cell therapy that are enriched with Prx1+ fibroblasts.