Exosomes as Targeted Delivery Platform of CRISPR/Cas9 for Therapeutic Genome Editing

Therapeutic genome editing harnesses the power of genome editing tools to correct erroneous genes associated with disease pathology. To bring the CRISPR/Cas9 tool from the bench to the bedside, a critical hurdle is to safely and efficiently deliver the nucleic acid tool to the desired type of cells in patients. This review discusses the use of natural-born carriers, extracellular vesicles (EVs), in particular exosomes, to fill up the gap. Exosomes are lipid-containing nanovesicle released by various types of cells to mediate cell-cell communications. Their inherent long-distance transportation capability, biocompatibility, and engineerability have made EVs potential vehicles for delivering therapeutic drugs. We summarize the recent progress of harnessing exosomes as delivery vehicles for the CRISPR/Cas system to achieve therapeutic gene editing for disease treatment, with a focus on various strategies to achieve selective delivery to a particular type of cells and efficient packaging of the genome editing tools in the vesicles. Critical issues and possible solutions in the design and engineering of the targeting vehicles are highlighted. Taken together, we manifest EV/exosome-mediated packaging of the nucleic acid/protein tools and the cell/tissue-targeted delivery as a viable way towards the clinical translation of the CRISPR/Cas9 technology.