Delivery approaches for CRISPR/Cas9 therapeutics in vivo: advances and challenges

ABSTRACT

Introduction: Therapeutic gene editing is becoming a viable biomedical tool with the emergence of the CRISPR/Cas9 system. CRISPR-based technologies have promise as a therapeutic platform for many human genetic diseases previously considered untreatable, providing a flexible approach to high-fidelity gene editing. For many diseases, such as sickle-cell disease and beta thalassemia, curative therapy may already be on the horizon, with CRISPR-based clinical trials slated for the next few years. Translation of CRISPR-based therapy to in vivo application however, is no small feat, and major hurdles remain for efficacious use of the CRISPR/Cas9 system in clinical contexts.

Areas covered: In this topical review, we highlight recent advances to in vivo delivery of the CRISPR/Cas9 system using various packaging formats, including viral, mRNA, plasmid, and protein-based approaches. We also discuss some of the barriers which have yet to be overcome for successful translation of this technology.

Expert opinion: This review focuses on the challenges to efficacy for various delivery formats, with specific emphasis on overcoming these challenges through the development of carrier vehicles for transient approaches to CRISPR/Cas9 delivery in vivo.

KEYWORDS:

• CRISPR/Cas9
• gene therapy
• in vivo genome editing
• therapeutic strategies
• nonviral delivery
• viral delivery
• intracellular delivery

Article highlights

• CRISPR/Cas9 editing provides a powerful method for the treatment of genetic disease.

• The CRISPR/Cas9 machinery can be packaged in various formats, each with inherent pros and cons.

• Multiple biological and synthetic approaches have been used to deliver the CRISPR/Cas9 editing machinery.

• Intracellular and nuclear delivery of editing machinery is critical for efficacy.

• Delivery approaches must remain viable in vivo to have future clinical translatability.

• Despite advances in the field of in vivo CRISPR/Cas9 delivery, challenges still remain to biocompatibility, safety, and tissue specificity.

This box summarizes key points contained in the article.

Declaration of interest

The authors have no relevant affiliations or financial involvement with any organization or entity with a financial interest in or financial conflict with the subject matter or materials discussed in the manuscript. This includes employment, consultancies, honoraria, stock ownership or options, expert testimony, grants or patents received or pending, or royalties.

Reviewer disclosure

Peer reviewers on this manuscript have no relevant financial or other relationships to disclose.

Additional information

Funding

This work was supported by the NIH (GM008515, DCL), (GM077173 and EB022641, VMR)