Graduate Studies


First Advisor

Angela K. Pannier

Second Advisor

Amanda E. Ramer-Tait

Date of this Version

Summer 6-2023

Document Type



Heck, K. (2023). Investigation of Commensal E. coli Outer Membrane Vesicles for Oral Delivery Application. University of Nebraska - Lincoln.


A THESIS Presented to the Faculty of The Graduate College at the University of Nebraska In Partial Fulfillment of Requirements For the Degree of Master of Science, Major: Agricultural and Biological Systems Engineering, Under the Supervision of Professors Angela K. Pannier & Amanda E. Ramer-Tait

Lincoln, Nebraska: June 2023

Copyright © 2023, Kari Heck


Gene and drug delivery via the oral route is desirable due to the high rate of patient compliance and ease of administration; however, the oral route presents many challenges to successful gene delivery. To overcome these challenges, we propose a novel bacterial-based material, outer membrane vesicles (OMVs), for oral delivery. Bacteria residing in the human gut, including Escherichia coli (E. coli), produce OMVs, which act similarly to exosomes by protecting and trafficking bioactive cargo. OMVs can survive gastric transit, cross the mucus barrier, and be internalized by intestinal cells, making OMVs an ideal biomaterial for oral delivery. Here, we screened a collection of OMVs isolated from 30 human commensal E. coli strains for characteristics relevant to oral delivery (e.g., immune modulation and internalization). Our results demonstrate that within a bacterial species, OMVs isolated from different strains exhibit a range of internalization by and immune modulation of intestinal epithelial cells and macrophages. Although we observed strain-specific differences in the ability of OMVs to induce cytokine production, all OMVs in this collection generally tended to be pro-inflammatory. Additionally, significant differences in OMV internalization were observed in both intestinal epithelial cells and macrophages among the 30 strains investigated, indicating that some OMVs may be more beneficial than others for oral delivery applications. Altogether, these findings demonstrate that bacterial strain of origin affects characteristics of E. coli OMVs that are relevant to oral drug and gene delivery applications.

Advisors: Angela K. Pannier & Amanda E. Ramer-Tait