Functional Biointegration of Bioengineered Salivary Tissues in Irradiated Animal Models

The ultimate goal of this project is to develop a fully functional, implantable human salivary gland for patients suffering from xerostomia, or chronic dry mouth, subsequent to radiation therapy for head and neck cancer. Our team recently developed an immunosuppressed, irradiated human-in-miniswine animal model for preclinical translation of a patented tissue engineered salivary tissue replacement we call the 3D-ST. This large animal model is suitable for testing cell-based projects designed to restore salivary function that includes both water secretion and protein/enzyme production needed to initiate digestion and maintain health of the oral cavity. Complementing this, a radiated nude rat model we developed serves as a useful model for testing product designs purposed to maximize biointegration including both vasculature and nerve needed for longterm organ success. Our successful interdisciplinary team includes the Farach-Carson/Wu team at UTHealth, the Lombaert team in Michigan, and the Swegal surgical team in Pittsburgh. Functioning at three sites, we developed a demonstrated workflow for experimental success that takes advantage of the unique facilities at each site. This proposal builds on our exciting supporting data using irradiated models to demonstrate the ability of transplanted hS/PCs in the 3D-ST to restore salivary secretory function. While our work to date showed long term (3-4 months) viability of implanted human/stem progenitor cells (hS/PCs) in the 3D-ST construct in both immunosuppressed miniswine and nude rats, a significant hurdle remains to foster complete, permanent biointegration of the 3D-ST with the host implant bed. Biointegration of vasculature with salivary acini is needed to provide nutrition and to supply the fluid component of saliva. Stable innervation is critical for glandular morphogenesis, achievement of cell polarity for directional secretion, and restoration of autonomic stimulation of secretion. This proposal builds on our exciting supporting data to encourage transplanted human hS/PCs to reestablish salivary secretory function and moves our focus from design optimization and implant viability to successful functional biointegration using our two irradiated models. We hypothesize that both vasculature and peripheral nerve integration of the 3D-ST can be achieved to stabilize the differentiated salivary phenotype. The two aims will: 1) use a quantitative scoring system to evaluate biointegration of vasculature and autonomic nervous system into implanted 3D-STs in irradiated animal models and determine impact on salivary cell phenotype; and 2) evaluate the ability of the transplanted 3D-ST to restore salivary function. Successful achievement of these aims will improve existing xenotransplant models for testing a variety of adult stem/progenitor cell-based therapies to replace exocrine organs and open the door to first-inhuman trials for relief of xerostomia.