Engineering approaches to model and restore ocular health

Eye injuries and vision-related disorders affect millions of Americans annually, imposing a multi billion-dollar burden on health care systems and a similarly hefty toll on patient quality of life. In many patients with impaired vision, the ocular surface is damaged due to acute injury or chronic inflammation. Therefore, identifying strategies to model and restore ocular health represents a promising approach for reducing the personal and societal costs associated with sight-threatening pathologies. The first half of this dissertation presents injectable hydrogels and fibrous matrices anticipated to be useful for delivering therapeutic cargo to injured ocular tissue and modulating its repair. In hydrogel biomaterials, binding thermodynamics and crosslink kinetics directly affect many bulk properties relevant to corneal wound healing, including viscoelasticity and macromolecule transport. However, present strategies to incorporate adapatable linkages in cell-compatible hydrogels rely on a relatively small number of covalent chemical reactions and host-guest interactions. To expand this toolkit, we designed biocompatible, supramolecular gelatin hydrogels with cucurbit[8]uril (CB[8])-based crosslinks that form on demand via thiol-ene reactions between preassembled CB[8]·FGGC peptide ternary complexes and grafted norbornenes. The resulting gels are injectable, shear thinning, and self-healing, enabling direct application from a syringe to a wound site without requiring an additional trigger such as light, heat, or catalyst that may adversely affect sensitive surrounding tissues such as the retina. Additional work exploited recombinant elastin like proteins (ELPs) to prepare fibrous matrices with biomimetic architecture and predictable, modular bioactivity and investigated their potential in controlled drug delivery and neural tissue engineering applications. The second half of this dissertation describes an in vitro dry eye disease (DED) model employing a live cell rheometer that simulates and quantifies blink induced mechanical forces between multilayers of mucin-deficient corneal and conjunctival epithelial cells. In contrast to previously reported preclinical models for screening ocular lubricants, which rely on scarce, heterogeneous tissue samples or model substrates that do not capture the complex biochemical and biophysical cues present at the ocular surface, this DED model harnesses immortalized human cell lines capable of reproducibly differentiating into physiological, stratified cellular layers. To emulate the surface chemistry changes that lead to altered mechanical interactions in DED patients, live, stratified cell layers are treated with the mucin-specific protease StcE. This biomimetic platform recapitulates the frictional damage observed in DED patients, enabling facile in vitro study of anti-adhesion, biolubrication, and barrier protection properties at the ocular surface. Taken as a whole, the work presented in this thesis demonstrates the power of engineering approaches in identifying and investigating therapeutic modalities for injured ocular tissues

Keywords: Myung, David degree supervisor.
Chemical Engineering.
Advisor: Fuller Gerald G.
Dunn Alexander Robert