Project Description The advancement of regenerative medicine has provided many new potential treatments for craniofacial bone defects, in which mesenchymal stem/progenitor cells (MSCs) play a critical role in maintaining constant remodeling of tissue architecture. The neural crest derived orofacial MSCs (OMSCs), such as stem cells from apical papilla (SCAP) are attractive postnatal stem cells for hard tissue regeneration, based on their superior osteogenic properties compared to their bone marrow counterparts. However, clinical translation remains challenging due to limited knowledge about the mechanisms of action. Ferumoxytol, an FDA-approved iron oxide nanoparticle formulation, exhibits several biomedical properties including anticancer and immunomodulation, based on its inherent physicochemical properties that activates cell proliferation, migration, and differentiation. Given these properties, ferumoxytol could be applied in MSC-based tissue regeneration, an unexplored avenue. Specifically, our goal is to identify whether ferumoxytol can activate orofacial MSCs and promote their multipotent differentiation capabilities and immunomodulation for endogenous tissue regeneration. Using RNA sequencing (RNA-seq) analysis and in vitro MSC characterization, we found intriguing data demonstrating that: 1) ferumoxytol significantly promotes stemness of SCAP through elevation of MSC markers and osteogenic progenitor markers, 2) proliferation and osteogenic capabilities are highly activated in SCAP after ferumoxytol treatment, 3) ferumoxytol largely increased immunomodulation of SCAP via PGE2/IDO cascades, and 4) YAP/TAZ are required mediators in ferumoxytol-mediated metabolic reconfiguration of SCAP for tissue regeneration. Based on these findings, we hypothesize that ferumoxytol activates YAP/TAZ signaling and promotes stemness of orofacial MSCs, which provides a favorable physiochemical microenvironment for enhancement of MSC viability and osteogenesis for autotherapies. During this proposal, I will explore the role of ferumoxytol in activation of somatic OMSCs to address how YAP/TAZ-mediated metabolic switch regulates OMSC homeostasis (Aim 1). Since immune components can impair somatic stem cell function and ferumoxytol treatment significantly elevated cell proliferation and osteogenesis through activation of YAP/TAZ cascades, we will determine whether activation of YAP/TAZ by ferumoxytol treatment may elevate endogenous craniofacial tissue regeneration in a ligature- induced periodontitis mouse model. A tetracycline-inducible postnatal neural-crest-specific YAP/TAZ knockout mouse model will be generated to examine in vivo stem cell behavior and endogenous tissue regeneration ability (Aim 2). Upon successful completion of the Specific Aims, this translational study will extend our knowledge in activating somatic stem cell abilities through repurposing an FDA approved nanoformulation for a new biomedical application.