Exosome as a Natural Gene Delivery Vector for Cancer Treatment

Background: Current gene therapy vectors such as viral, non-viral, and bacterial vectors, which are used for cancer treatment, but there are certain safety concerns and stability issues of these conventional vectors. Exosomes are the vesicles of size 40-100 nm secreted from multivesicular bodies into the extracellular environment by most of the cell types in-vivo and in-vitro. As a natural nanocarrier, exosomes are immunologically inert, biocompatible, and can cross biological barriers like the blood-brain barrier, intestinal barrier, and placental barrier. Objective: This review focusses on the role of exosome as a carrier to efficiently deliver a gene for cancer treatment and diagnosis. The methods for loading of nucleic acids onto the exosomes, advantages of exosomes as a smart intercellular shuttle for gene delivery and therapeutic applications as a gene delivery vector for siRNA, miRNA and Clustered Regularly Interspaced Short Palindromic Repeats (CRISPR) and also the limitations of exosomes as a gene carrier are all reviewed in this article. Methods: Mostly, electroporation and chemical transfection are used to prepare gene loaded exosomes. Results: Exosome-mediated delivery is highly promising and advantageous in comparison to the current delivery methods for systemic gene therapy. Targeted exosomes, loaded with therapeutic nucleic acids, can efficiently promote the reduction of tumor proliferation without any adverse effects. Conclusion: In the near future, exosomes can become an efficient gene carrier for delivery and a biomarker for the diagnosis and treatment of cancer.

No more helper adenovirus: production of gutless adenovirus (GLAd) free of adenovirus and replication-competent adenovirus (RCA) contaminants

Gene therapy is emerging as an effective treatment option for various inherited genetic diseases. Gutless adenovirus (GLAd), also known as helper-dependent adenovirus (HDAd), has many notable characteristics as a gene delivery vector for this particular type of gene therapy, including broad tropism, high infectivity, a large transgene cargo capacity, and an absence of integration into the host genome. Additionally, GLAd ensures long-term transgene expression in host organisms owing to its minimal immunogenicity, since it was constructed following the deletion of all the genes from an adenovirus. However, the clinical use of GLAd for the treatment of inherited genetic diseases has been hampered by unavoidable contamination of the highly immunogenic adenovirus used as a helper for GLAd production. Here, we report the production of GLAd in the absence of a helper adenovirus, which was achieved with a helper plasmid instead. Utilizing this helper plasmid, we successfully produced large quantities of recombinant GLAd. Importantly, our helper plasmid-based system exclusively produced recombinant GLAd with no generation of helper plasmid-originating adenovirus and replication-competent adenovirus (RCA). The recombinant GLAd that was produced efficiently delivered transgenes regardless of their size and exhibited therapeutic potential for Huntington’s disease (HD) and Duchenne muscular dystrophy (DMD). Our data indicate that our helper plasmid-based GLAd production system could become a new platform for GLAd-based gene therapy.