CRISPR/Cas System for Genome Editing: Progress and Prospects as a Therapeutic Tool

• Published in: The Journal of pharmacology and experimental therapeutics 2019-09, Vol.370 (3), p.725-735
• Main Authors: Sahel, Deepak Kumar, Mittal, Anupama, Chitkara, Deepak
• Format: Article
• Language: English
• Subjects: Animals; CRISPR-Cas Systems; Gene Editing - methods; Gene Transfer Techniques - trends; Genetic Therapy - trends; Humans
• ISSN: 0022-3565; 1521-0103
• DOI: 10.1124/jpet.119.257287

CRISPR was first observed in 1987 in bacteria and archaea and was later confirmed as part of bacterial adaptive immunity against the attacking phage. The CRISPR/Cas restriction system involves a restriction endonuclease enzyme guided by a hybrid strand of RNA consisting of CRISPR RNA and trans-activating RNA, which results in gene knockout or knockin followed by nonhomologous end joining and homology-directed repair. Owing to its efficiency, specificity, and reproducibility, the CRISPR/Cas restriction system was said to be a breakthrough in the field of biotechnology. Apart from its application in biotechnology, CRISPR/Cas has been explored for its therapeutic potential in several diseases including cancer, Alzheimer's disease, sickle cell disease, Duchenne muscular dystrophy, neurologic disorders, etc., wherein CRISPR/Cas components such as Cas9/single guide RNA (sgRNA) ribonucleoprotein, sgRNA/mRNA, and plasmid were delivered. However, limitations including immunogenicity, low transfection, limited payload, instability, and off-target binding pose hurdles in its therapeutic use. Nonviral vectors (including cationic polymers, lipids, etc.), classically used as carriers for therapeutic genes, were used to deliver CRISPR/Cas components and showed interesting results. Herein, we discuss the CRISPR/Cas system and its brief history and classification, followed by its therapeutic applications using current nonviral delivery strategies.