CRISPR/Cas9 Technology: Challenges and drawbacks

Abstract

Genome engineering has been transformed in recent years by the introduction of the CRISPR technology for a variety of cancer research projects spanning from fundamental science to translational medicine and precision cancer treatment. Although there have been tremendous advancements in this area, a number of technical issues still need to be resolved, including off- target activity, inadequate indel or poor homology-directed repair (HDR) efficiency, in vivo distribution of the Cas system components, and immunological reactions. Chromosome rearrangements brought on by off-target effects might unintentionally affect some poorly matched genomic locations and restrict the use of CRISPR-Cas editing technologies for therapeutic reasons. Studies have shown that CRISPR-Cas tools may be more susceptible to off-target effects than some of the other common gene-editing techniques because a Cas protein is a monomer that might accidentally enhance the identification of shorter target sequences, whereas the TALEN and ZFN assemblies are dimeric. Off-target effects often come from Cas enzymes that cleave bystanders (not intended targets) and guide RNA to recognize mismatches. CRISPR systems delivered in vivo can trigger immune responses against foreign substances by significantly increasing people's innate immunity and/or adaptive immunity. Guide RNAs may be used to initiate innate immune responses. This article provides an overview of CRISPR-Cas applications from the lab to the clinic, identifies current barriers that may restrict the use of CRISPR-Cas systems as gene-editing toolkits in precision medicine, and offers some perspectives on how to address these barriers and speed up technical advancement