Directing stem cell behavior in an engineered vocal fold-like microenvironment
Date
2019
Authors
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Publisher
University of Delaware
Abstract
The overall goal of this doctoral dissertation is to understand how microenvironmental cues direct the phenotype and function of human mesenchymal stem cells (hMSCs) in the context of vocal fold (VF) tissue repair and regeneration. To assess the therapeutic efficacy of stem cell-based therapies for the treatment of vocal fold scarring, VF-mimetic hydrogels were developed consisting of a covalent hyaluronic acid (HA)-based network interpenetrated by assembled collagen fibrils. When hMSCs were cultured in these gels, they adopted a phenotype and expression pattern reminiscent of cells involved in the wound healing process. To understand the effects of phonation on hMSC differentiation, a bioreactor capable of the induction of high frequency (200 Hz) oscillatory air pressure was designed, constructed and characterized. Vibratory culture of hMSCs in HA/collagen gels over a 3-day, 1h-on 1h-off cycle resulted in significant downregulation of fibrogenic markers and loss of alpha smooth muscle actin positive staining, indicating attenuation of myofibrogenic potential and a further shift away from a fibrotic phenotype. Finally, the roles of connective tissue growth factor (CTGF) in promoting tissue fibrosis were investigated. hMSCs were encapsulated within a cell-adhesive, protease-degradable HA network devoid of any collagen fibrils and cell culture was maintained in CTGF-conditioned media for 21 days. CTGF promoted fibrogenesis through mitogen activated protein kinase (MAPK)-dependent regulation. Overall, this work presents several in vitro models for future therapeutic endeavors aimed towards limiting scar formation in VF tissues.
Description
Keywords
3D cell culture, Biomechanics, Hydrogels, Vibration, Vocal fold, Human mesenchymal stem cells