PROJECT ABSTRACT Diabetes mellitus significantly delays the healing of epidemic wounds as well as oral wounds, posing a difficult clinical challenge for oral surgeries such as tooth extractions and free flaps. The lack of comprehensive knowledge regarding the effects of diabetes on oral mucosal health hinders the design of effective treatment. Our long-term goal is to identify novel therapeutic targets to improve diabetic wound management. In our preliminary study, we discovered that long-lived Wnt-responsive cells are stem cells in oral epithelia. These cells reside in the basal layer of the oral epithelium and maintain the tissue’s turnover and barrier function by precisely balancing proliferation and differentiation. In response to injury, Wnt-responsive cells prioritize proliferation over differentiation, producing abundant progeny to quickly re-epithelialize the wound. In diabetic mice, we recently discovered that oral epithelia exhibit a decreased turnover rate and reduced structural protein expression. The overall objective of this proposal is to determine how diabetes affects the quantity, distribution, activity, and injury response of oral epithelial stem cells using both in vitro and in vivo models. Our central hypothesis is that diabetes disrupts the microenvironment of oral epithelial stem cells, impairs stem cell fate, and thus adversely affects epithelial barrier function and wound healing. Two independent but interconnected aims are proposed. In AIM 1, we will determine the alterations that occur in oral epithelial stem cells and their niche under diabetic conditions. Based on our preliminary data, we hypothesize that diabetes negatively impacts oral epithelial stem cells and their niche, leading to slowed tissue turnover and compromised barrier function. A novel lineage-tracing strain will be used to examine the quantity and activity of Wnt-responsive cells in an adult-onset type 2 diabetes model, which closely resembles patient metabolic characteristics. Niche signaling will be interrogated by an in vitro 3D coculture model. In AIM 2, we will define the key mechanisms responsible for delayed diabetic wound healing. We hypothesize that the ineffective response of epithelial stem cells to injury is the primary cause of the compromised healing of diabetic wounds. We will challenge control and diabetic mice with a traumatic oral ulcer model and monitor the healing process, focusing on stem cell activation, proliferation, migration, and differentiation. Results from this proposal will demonstrate for the first time the extent to which diabetes alters epithelial stem cells in homeostasis and wound healing. These results are expected to have positive impacts, as a comprehensive understanding of the compromised state of epithelial stem cells under diabetic conditions will facilitate the development of effective therapies to enhance wound management.