Copyright ©The Author(s) 2016. Published by Baishideng Publishing Group Inc. All rights reserved.
World J Med Genet. Aug 27, 2016; 6(3): 22-33
Published online Aug 27, 2016. doi: 10.5496/wjmg.v6.i3.22
Chitosan DNA nanoparticles for oral gene delivery
Bhavika J Patel, Nithin K Vignesh, Gonzalo Hortelano
Bhavika J Patel, Nithin K Vignesh, Department of Health Sciences, McMaster University, Hamilton, Ontario L8N 3Z5, Canada
Gonzalo Hortelano, Department of Biology, School of Science and Technology, Nazarbayev University, Astana 010000, Kazakhstan
Gonzalo Hortelano, School of Biomedical Engineering, McMaster University, Hamilton, Ontario L8N 3Z5, Canada
Gonzalo Hortelano, Department of Pathology and Molecular Medicine, McMaster University, Hamilton, Ontario L8N 3Z5, Canada
Author contributions: All authors contributed to this paper with conception and design of the study, literature review and analysis, drafting and critical revision and editing, and final approval of the final version.
Conflict-of-interest statement: Non declared.
Open-Access: This article is an open-access article which was selected by an in-house editor and fully peer-reviewed by external reviewers. It is distributed in accordance with the Creative Commons Attribution Non Commercial (CC BY-NC 4.0) license, which permits others to distribute, remix, adapt, build upon this work non-commercially, and license their derivative works on different terms, provided the original work is properly cited and the use is non-commercial. See:
Correspondence to: Gonzalo Hortelano, PhD, Department of Biology, School of Science and Technology, Nazarbayev University, Astana 010000, Kazakhstan.
Telephone: +7-717-2705782
Received: January 17, 2016
Peer-review started: January 18, 2016
First decision: February 29, 2016
Revised: July 20, 2016
Accepted: August 6, 2016
Article in press: August 8, 2016
Published online: August 27, 2016

Gene therapy is a promising technology with potential applications in the treatment of medical conditions, both congenital and acquired. Despite its label as breakthrough technology for the 21st century, the simple concept of gene therapy - the introduction of a functional copy of desired genes in affected individuals - is proving to be more challenging than expected. Oral gene delivery has shown intriguing results and warrants further exploration. In particular, oral administration of chitosan DNA nanoparticles, one the most commonly used formulations of therapeutic DNA, has repeatedly demonstrated successful in vitro and in vivo gene transfection. While oral gene therapy has shown immense promise as treatment options in a variety of diseases, there are still significant barriers to overcome before it can be considered for clinical applications. In this review we provide an overview of the physiologic challenges facing the use of chitosan DNA nanoparticles for oral gene delivery at both the extracellular and intracellular level. From administration at the oral cavity, chitosan nanoparticles must traverse the gastrointestinal tract and protect its DNA contents from significant jumps in pH levels, various intestinal digestive enzymes, thick mucus layers with high turnover, and a proteinaceous glycocalyx meshwork. Once these extracellular barriers are overcome, chitosan DNA nanoparticles must enter intestinal cells, escape endolysosomes, and disassociate from genetic material at the appropriate time allowing transport of genetic material into the nucleus to deliver a therapeutic effect. The properties of chitosan nanoparticles and modified nanoparticles are discussed in this review. An understanding of the barriers to oral gene delivery and how to overcome them would be invaluable for future gene therapy development.

Keywords: Gene therapy, Oral gene delivery, Chitosan nanoparticles, Glycocalyx, pH, Enzymes, Endolysosomal escape, Intracellular transport, Nuclear transport, Mucus

Core tip: Gene therapy is facing considerable challenges to realize its promise, the most important which is arguably achieving effective delivery of the therapeutic gene to the target cells. Therefore, developing alternative delivery strategies is crucial. This manuscript reviews the oral administration of chitosan DNA nanoparticles as a novel gene therapy delivery strategy.