CRISPR Gene Therapy: Applications, Limitations, and Implications for the Future.

Fathema Uddin,Charles M Rudin,Triparna Sen

doi:10.3389/fonc.2020.01387

Abstract

A series of recent discoveries harnessing the adaptive immune system of prokaryotes to perform targeted genome editing is having a transformative influence across the biological sciences. The discovery of Clustered Regularly Interspaced Short Palindromic Repeats (CRISPR) and CRISPR-associated (Cas) proteins has expanded the applications of genetic research in thousands of laboratories across the globe and is redefining our approach to gene therapy. Traditional gene therapy has raised some concerns, as its reliance on viral vector delivery of therapeutic transgenes can cause both insertional oncogenesis and immunogenic toxicity. While viral vectors remain a key delivery vehicle, CRISPR technology provides a relatively simple and efficient alternative for site-specific gene editing, obliviating some concerns raised by traditional gene therapy. Although it has apparent advantages, CRISPR/Cas9 brings its own set of limitations which must be addressed for safe and efficient clinical translation. This review focuses on the evolution of gene therapy and the role of CRISPR in shifting the gene therapy paradigm. We review the emerging data of recent gene therapy trials and consider the best strategy to move forward with this powerful but still relatively new technology.

Highlights

Gene therapy as a strategy to provide therapeutic benefit includes modifying genes via disruption, correction, or replacement [1]
Gene therapy enjoyed an initial phase of excitement, until the recognition of immediate and delayed adverse effects resulted in death and caused a major setback
The discovery and development of Clustered Regularly Interspaced Short Palindromic Repeats (CRISPR)/Cas9 has re-opened a door for gene therapy and changed the way scientists can approach a genetic aberration—by fixing a nonfunctional gene rather than replacing it entirely, or by disrupting an aberrant pathogenic gene

Summary

INTRODUCTION

Gene therapy as a strategy to provide therapeutic benefit includes modifying genes via disruption, correction, or replacement [1]. While the other gene-editing tools can induce genome editing at targeted sites under controlled conditions, the CRISPR/Cas system has largely supplanted these earlier advances due to its relatively low price, ease of use, and efficient and precise performance This technology is often delivered with adeno-associated virus (AAV) vectors, and does not completely avert risks associated with viruses. The potential use of this system was simplified by introducing a synthetic combined crRNA and tracrRNA construct called a single-guide RNA (sgRNA) [28] This was followed by studies demonstrating successful genome editing by CRISPR/Cas in mammalian cells, thereby opening the possibility of implementing CRISPR/Cas in gene therapy [29] (Figure 1). NHEJ occurs much more frequently in most cell types and involves random insertion and deletion

LIMITATIONS AND ADVANCEMENTS

Findings

DISCUSSION