Recent advances in the delivery and applications of nonviral CRISPR/Cas9 gene editing

Abstract

Abstract The CRISPR (clustered regularly interspaced short palindromic repeats)/Cas9 genome editing system has been a major technological breakthrough that has brought revolutionary changes to genome editing for therapeutic and diagnostic purposes and precision medicine. With the advent of the CRISPR/Cas9 system, one of the critical limiting factors has been the safe and efficient delivery of this system to cells/tissues of interest. Several approaches have been investigated to find delivery systems that can attain tissue-targeted delivery, lowering the chances of off-target [PM2] editing. While viral vectors have shown promise for in vitro, in vivo and ex vivo delivery of CRISPR/Cas9; further clinical applications have been restricted due to shortcomings including: limited packaging capacity, difficulties with large-scale production, immunogenicity and insertional mutagenesis. Rapid progress in nonviral delivery vectors, including the use of lipid, polymer, peptide and inorganic nanoparticle-based delivery systems, has established nonviral delivery approaches as a viable alternative to viral vectors. This review will introduce the molecular mechanisms of the CRISPR/Cas9 gene editing system, current strategies for delivering CRISPR/Cas9-based tools, an overview of strategies for overcoming off-target genome editing, and approaches for improving sequence targeting, genome targeting and tissue targeting. We will also highlight current developments and recent clinical trials for the delivery of CRISPR/Cas9. Finally, future directions for overcoming the limitations and adaptation of this technology for clinical trials will be discussed.