Project Summary: The ability to repair injured tissue quickly and properly is essential for human health. One notable feature of human aging is an age-associated delay in wound repair. Age-related changes in wound healing are of great clinical importance as they affect the response to acute injuries and also play a role in the development of chronic wounds. As the aging population continues to grow, so will the clinical and socioeconomic burdens of poorly healed and non-healing wounds. Skin aging is accompanied by a gradual change in resident cell populations and loss of function, resulting in a decreased ability to regulate homeostasis. Similarly, numerous defects in the complex process of wound healing are associated with aging, including changes in inflammation, proliferative processes, and the level of senescent cells. The large number of age-related changes that have been described in wounds suggests that the healing deficit may derive from changes in master regulators, such as small non-coding RNAs (sncRNAs). Indeed, in systems other than wounds, aging is known to involve numerous genetic and epigenetic changes, including changes in the expression of regulatory sncRNAs, such as microRNA and piwi-interacting RNA (piRNA). While the importance of sncRNAs in development, in the modulation of life span, and in the aging process has been established, the functional contribution(s) of sncRNAs to aging-associated healing deficits is unknown. Recent studies (including results from our group) provide direct evidence for a major role of sncRNAs in the regulation of normal wound healing. The goal of the current project is to determine whether the genetic/epigenetic program that controls optimal healing outcomes deteriorates during aging. Aim 1 will establish the dynamic sncRNA profiles of skin wounds from young and aged mice, and will identify microRNA and piRNA candidates that differentiate delayed wound healing in aged mice. Aim 2 will define the functional and mechanistic association of sncRNA alterations with the delayed wound healing of aged skin. Aim 3 will test whether therapeutic modulation of specific sncRNA in vivo will improve aged healing. The results will fulfill the unmet need of fully understanding how genomic dysregulation influences healing as we age. These studies will provide novel information about how sncRNAs contribute to age-related impaired healing dynamics. The investigation of this understudied area has the potential to suggest original therapeutic approaches for tissue repair and regeneration.