RECAPITULATION OF THE SALIVARY GLAND NICHE EX VIVO FOR STEM CELL BASED THERPIES

Saliva is an important defense mechanism for protecting oral health. Salivary gland (SG) hypofunctionresults in uncontrolled and severe oral diseases that lead to severely compromised quality of life. SGsare highly differentiated and have little regenerative capacity once they are destroyed by therapy ordisease (e.g. radiation therapy or autoimmune Sjgren?s syndrome). Therefore, the development ofstrategies for preserving or regenerating the secretory function of SGs is essential for successfulmanagement of these patients. The extracellular matrix (ECM) is a major component of the uniquemicroenvironment or ?niche? that directs and maintains the differentiated functions of cells in vivoPresently, there are two main obstacles to stem cell-based regenerative therapies: 1) the limitedavailability of multi-potent stem cells and 2) the difficulty of selectively controlling the differentiationmulti-potent stem cells into the desired cell lineage. Our research group has developed a novel ECM-based cell culture system for expanding multipotent mesenchymal stem cells (MSCs) from bonemarrow and 3D silk fibroin scaffolds (SFS) for establishing the SG niche ex vivo. Therefore, wepropose to test the hypothesis that salivary gland specific ECM (SG-ECM), established on a natural 3DSFS, is a biomimetic niche capable of directing MSC proliferation and differentiation into functional SGprogenitor cells. In Specific Aim 1, we will optimize scaffold characteristics for the production of SG-ECM on the SFS by primary SG epithelial cells. In Specific Aim 2, we will determine whether theoptimal SG-ECM coated SFS directs MSC differentiation into the SG cell lineage. In Specific Aim 3, theefficacy of the cells, produced in Specific Aim 2, will be evaluated in an in vivo model of SG damagedue to irradiation.The novelty of this proposal includes (1) testing our novel cell culture technology to obtain sufficientnumbers of multipotent MSCs from human bone marrow to repair or regenerate SG function; (2) testinga natural 3D scaffold material and optimizing its properties for supporting SG regeneration and tissueengineering; (3) examining the role of SG-derived ECM coated scaffolds in directing MSC differentiationto the SG cell lineage and functional SG units, and (4) assembling a multidisciplinary team to studystem-cell based SG therapy. The success of this study may lead to new therapeutic strategies forclinical management of SG dysfunction.