Designing Spatiotemporally Tunable Viscoelastic Hyaluronic Acid Hydrogels to Study Cell Mechanobiology During Fibrosis
Hui, Erica, Chemical Engineering - School of Engineering and Applied Science, University of Virginia
Caliari, Steven, EN-Chem Engr Dept, University of Virginia
The ECM is highly dynamic and is constantly regulated through cell-cell and cell-matrix interactions. ECM dysregulation can trigger various signaling cascades and promote deviant cell behaviors and disease progression. Fibrosis is a heterogeneous pathological scarring outcome of many diseases that is characterized by progressive matrix stiffening and decreasing viscoelasticity. Treatments have been largely unsuccessful due to a lack of suitable test systems for probing molecular mechanisms involved in fibrogenesis. Additionally, most hydrogel models fail to display tissue-relevant time-dependent properties such as stress relaxation, which has shown to be a critical regulator of cell phenotype. Engineered hydrogels with tunable properties has become a powerful method to study the mechanoregulatory role of mechanical and biochemical cues on cell behaviors. Overall, the goal of this thesis is to develop a class of mechanically dynamic and spatiotemporally heterogeneous hydrogels with precise control over cell-instructive inputs, allowing recapitulation of both normal and diseased microenvironments.
For this work, we used phototunable hyaluronic acid (HA)-based hydrogels that enable independent tuning of stiffness, viscoelasticity, and adhesive ligand presentation to understand how physical and chemical cues collectively influence cell behaviors in fibrosis. Chapter 3 characterizes the time-dependent properties of ex vivo tissue, such as stress relaxation and frequency-dependent behavior, to direct the design of ECM-mimetic biomaterials. Chapter 4 illustrates the development of an in vitro fibrosis model to study how stiffness, viscoelasticity, and heterogeneity influences fibroblast response. Chapter 5 uses engineered fibronectin adhesive fragments to understand the individual and combined roles of stiffness, viscoelasticity, and adhesion on cell spreading, actin stress fiber formation, and focal adhesion maturation. Finally, Chapter 6 explores how viscoelastic cues impact cell behaviors in 3D cultures. Altogether, these studies present a framework for engineering instructive hydrogel platforms that offer greater insight into the role that complex matrix properties play in regulating cell mechanobiology in the context of fibrosis progression.
PHD (Doctor of Philosophy)
Biomaterials, Hydrogels, Viscoelasticity, Hyaluronic Acid, Fibrosis, Mechanobiology