Era of Genomic Medicine: A Narrative Review on CRISPR Technology as a Potential Therapeutic Tool for Human Diseases

Abstract

Clustered Regularly Interspaced Short Palindromic Repeats (CRISPR) provides acquired immunity in microorganisms against exogenous DNA that may hinder the survival of the organism. Pioneering work by Doudna and Charpentier in 2012 resulted in the creation of the CRISPR/Cas9 genome editing tool on the basis of this concept. The aim of this was to create a rapid, efficient, and versatile genome-editing tool to facilitate genetic manipulation. The mechanism relies on two components: the RNA guide which acts as a sentinel and a Cas protein complex which functions as a highly precise molecular knife. The guide RNA can be modified to match a DNA sequence of interest in the cell and accordingly be used to rectify mutations that may otherwise cause disease. Within a few years following the development of the CRISPR/Cas9 tool, its usage has become ubiquitous. Its influence extends into many fields of biological sciences from biotechnology and biochemistry to molecular biology and biomedical sciences. The following review aims at shedding some light on to the applications of the CRISPR/Cas9 tool in the field of biomedical sciences, particularly gene therapy. An insight with relation to a few of the many diseases that are being tackled with the aid of the CRISPR/Cas9 mechanism and the trends, successes, and challenges of this application as a gene therapy are discussed in this review.

Therapeutic promise of engineered nonsense suppressor tRNAs

“…There are several promising uses of CRISPR/Cas technologies for nonsense mutation intervention that includes prime editing, homologous recombination following double‐stranded breaks, and in‐frame deletions. However, there already exist several excellent reviews that cover the exciting possibilities of CRISPR/Cas (Knott & Doudna, 2018; Komor et al, 2017; Kotagama et al, 2019). It should be noted that the two approaches, targeted pseudouridylation, and CRISPR/Cas editing depend on the genomic context for targeting and therefore will confer no NTC readthrough, however, toxicity may occur through other off‐target mechanisms.…”

Mechanism and Applications of CRISPR/Cas-9-Mediated Genome Editing

“…Immunogenicity, lack of a safe and efficient delivery system to the target, off-target effect, and ethical issues have been the major barriers to extend the technology in clinical applications. 52 Since the components of the CRISPR/Cas-9 system are derived from bacteria, host immunity can elicit an immune response against these components. Researchers also found that there were both pre-existing humoral (anti-Cas-9 antibody) and cellular (anti-Cas-9 T cells) immune responses to Cas-9 protein in healthy humans.…”

“…Since the technology is still in its infancy and knowledge about the genome is limited, many scientists restrain that it still needs a lot of work to increase its accuracy and make sure that changes made in one part of the genome do not have unforeseen consequences, especially in the application towards human trials. 52…”

Harnessing the Potential of CRISPR/Cas in Atherosclerosis: Disease Modeling and Therapeutic Applications

“…Alternatively, viral systems offer higher genome editing efficiency in vitro/in vivo and provide the advantage of natural tropism for specific cell types, along with long-term transgene expression [49,91]. To date, the AAV viral delivery systems are frequently used for gene transduction due to its non-pathogenicity, mild immunogenicity, serotype specificity, and ability to infect proliferating and non-proliferating cells indiscriminately [99]. AAV-packaging plasmids such as adenoviral helper plasmid pAdDeltaF6 (PL-F-PVADF6) and AAV8 packaging vector pAAV2/8 (PL-T-PV0007) were co-transfected with the AAV-CRISPR plasmid into HEK293T to produce high viral titer, before intraperitoneally injected into mice.…”