Engineered biomaterials as intestinal epithelial cell culture platforms

The intestinal epithelium is a tissue structure that is intimately involved in human health, and is awash in an ocean of cue from their surrounding extracellular matrix and from adjacent cell types. In the midst of such an environment, the intestinal epithelium serves an integral purpose as the de facto barrier which orchestrates the dynamic, homeostatic equilibrium between the inside of the organism and the outside world. Unfortunately, diseases involving the gastrointestinal epithelium are all too common in humans. This abundance of digestive diseases has driven the desire to develop engineered models of the intestine, in order to study disease progression in simplified, controlled environments. Polymeric biomaterials are increasingly the focus of approaches to engineer models of the intestinal epithelium. These materials can be coarsely grouped into two main categories: synthetic and naturally-derived materials. In this thesis, strategies are presented which hybridize these synthetic and naturally-derived categories to produce improved models for intestinal epithelial cell culture. The first section of this dissertation details the use of a protein-engineered biomaterial as a culture substrate to improve the physiological accuracy of a commonly used preclinical model of drug absorption. We found that by independently tuning Elastin-Like Protein biomaterial stiffness and the density of a peptide ligand that engaged the mechanotransductive integrin receptors of Caco-2 cells, engineered matrices of lower stiffness and lower integrin-engaging peptide sequences resulted in the formation of Caco-2 monolayers that were more permissive to paracellularly transported drug molecules. The work described in the next section progresses from the 2D model described above, towards models in 3D, while still leveraging the ease and utility of epithelial cell lines. This section of work describes a two-component biomaterial system that is used to create a 3D hydrogel environment in which epithelial cells were encapsulated and cultured, and demonstrates these biomaterials as suitable for Caco-2 and MDCK-II spheroid culture. In the final section of this work, Hyaluronan Elastin-Like Protein (HELP) biomaterials are studied for the 3D culture of human patient-derived intestinal enteroids. This section describes one of the first synthetic, engineered materials for patient-derived enteroid culture, and demonstrates the wide-ranging utility of HELP biomaterials for epithelial organoid culture. In total, this work further solidifies the usefulness of engineered, tunable, and well-defined biomaterials in systematic studies which aim to affect relevant phenomena in intestinal epithelial model systems. The use of HELP biomaterials is the apex of the progression of this work, integrating multiple types of engineered materials, for the 3D culture of a highly physiologically relevant cell type. This material can now be used to study more applied phenomena in the intestinal organoid model system, as a compelling avenue of further study

Keywords: Chemical Engineering.
Advisor: Dunn Alexander Robert
Heilshorn Sarah
Amieva Manuel