Abstract

Intestinal Epithelium for Basic Physiology and Drug Assays

Nancy L Allbritton, Professor, University Of North Carolina

Organ-on-chips are miniaturized devices that arrange living cells to simulate functional subunits of tissues and organs. These microdevices provide exquisite control of tissue microenvironment for the investigation of organ-level physiology and disease. Human organ-on-chips are expected to transform biomedical research providing platforms that accurately replicate human tissues, enable a better understanding of human-to-human physiologic variations, and even permit patient-specific organ mimics. These human organ facsimiles will fundamentally alter drug discovery and development by providing human constructs for screening assays, toxicity measurements and investigation of molecular-level drug actions. Breakthroughs in stem-cell biology now enable single stem cells or intestinal crypts isolated from primary mouse or human intestine or differentiated from induced pluripotent stem cells (iPSCs) to grow and persist indefinitely in defined 3D culture conditions to form organotypic structures generically termed enteroids. We have developed a long-lived, self-renewing monolayer culture format from primary intestinal cells. A surface matrix and chemical factors sustain the epithelial cell monolayers so that they possess all cell repertoires found in vivo. This technical advance has made it possible to create primary tissues on platforms that are compatible with high-content screening strategies. For example, the screening of 77 dietary compounds revealed that these compounds altered proliferation to increase stem cell numbers or increased cell differentiation with formation of increased numbers of goblet cells or enterocytes. Measurement of drug transport and metabolism has also been demonstrated in these human intestinal monolayer systems as well as formation of physiologic mucus layers many hundreds of microns thick. Culture of these monolayers on a shaped scaffold under chemical gradients replicates much of the cell compartmentalization and physiology observed in vivo. This bioanalytical platform is envisioned as a next-generation system for assay of microbiome-, drug- and toxin-interactions with the intestinal epithelia. Finally, intestinal biopsy samples can be used to populate these constructs with cells producing patient-specific tissues for personalized medicine that can be applied to emerging areas of disease modeling and microbiome studies.