SUMMARY
Gene delivery via the oral route offers a promising strategy for improving gene-based therapy outcomes. The
non-invasive nature of oral delivery allows for ease of dosing, which can promote convenience and a high rate
of patient compliance. Moreover, oral administration facilitates both local and systemic production of therapeutic
genes. For local gene therapy for gastrointestinal (GI) diseases (e.g., metabolic and nutritional defects,
inflammatory bowel diseases and colon cancers), the oral route allows direct access to the affected tissue.
However, the highly vascularized nature of the GI tract also makes oral gene delivery a viable option for
administering systemic therapies, where transfection within intestinal cells results in production of protein that is
delivered into the bloodstream and circulated systemically. In addition, oral DNA delivery can be used as a
vaccination strategy, providing for both systemic and mucosal immunity. Although there is potential for oral gene
delivery to treat and vaccinate against a wide variety of diseases, the efficacy of nonviral delivery methods is
limited by carrier materials that cannot prevent DNA payload degradation in the harsh conditions of the GI tract
nor promote uptake by intestinal cells, which results in low transgene expression. To overcome challenges
associated with oral gene delivery, we propose to develop a novel, biological-based delivery platform by loading
outer membrane vesicles (OMVs) derived from commensal gut bacteria with plasmid DNA to create DNA-loaded
OMV nanocarriers (DNA-OMV NCs). OMVs are produced via budding of bacterial outer membranes and function
as a natural communication system for bacteria. OMVs protect and deliver secreted material, allowing bacteria
to influence their environment. Numerous commensal (non-pathogenic) bacteria residing in the human GI tract
secrete OMVs, and preliminary results from our team show that OMVs from commensal Escherichia coli (E. coli)
isolated from the human GI tract can be internalized by both intestinal epithelial cells and macrophages, elicit a
range of pro- or anti-inflammatory cytokine responses from macrophages, and survive gastric transit when orally
administered to mice. Moreover, we have shown in preliminary work that we can load OMVs (from a lab strain
of E. coli) with pDNA to create DNA-OMV NCs. We hypothesize that a DNA-OMV NC delivery platform will
protect loaded DNA through GI transit, facilitate uptake by epithelial cells and macrophages, elicit tunable
cytokine responses, and enable effective in vivo transfection. We will pursue two aims: 1) Screen OMVs isolated
from gut commensal E. coli strains for internalization, cytotoxicity, and immune modulation to develop a library
of OMVs for use as NCs for oral gene delivery; 2) Develop methods to produce DNA-OMV NCs and evaluate
their abilities to protect DNA cargo, modulate immune profiles, and mediate transfection. Specific to the Awards
Supporting Cutting-Edge Technologies for Translational Science (ASCETTS) funding opportunity, we expect to
develop a tunable, bio-inspired platform for oral gene delivery that leverages natural host-bacterial interactions
and is suitable for broad utilization in therapeutic applications, ranging from gene therapy to vaccination.
