CRISPR/Cas9 Gene Targeting

“Take risks and constantly challenge the status quo.”

Before being engaged in biomedical sciences, I was studying electronic engineering, so I always dreamed about being able to engineer genes and cells for treating human disease as we would for computer programs. After I switched to biological study, I realized that solid knowledge and understanding of life sciences spanning microbiology to human biology would be required to even begin working on this fascinating topic, let alone the goal of leveraging gene and cell engineering to tackle such high-impact challenges such as transplantation, immunotherapy, and autoimmune treatment. Thanks to my mentors, colleagues, as well as the incredibly collaborative biomedical community, despite an unusual start, I had a fascinating path that transformed an electronic engineering student to a bioengineer. But all technologies would need to root back to biology and medical translation if it were to generate lasting impact. In recent years, the amazing advancement in basic and clinical research has led to exciting new tools such as the clustered regularly interspaced short palindromic repeats (CRISPR)) system and its wide applications in diverse fields.

With increasingly more powerful CRISPR tools, the tremendous potential of gene editing in cellular therapy has manifested in a variety of settings, spanning (1) ex vivo editing of stem cells or immune cells as new generation of cancer cell therapy to overcome the shortcoming or enhance properties of existing therapies such as chimeric antigen receptor T cell, (2) ex vivo modification of stem cells or immune cells for transplantation for modulatory or regenerative treatment of human diseases such as hematopoietic disorders (e.g., sickle-cell anemia) or graft-versus-host disease, (3) direct in vivo therapeutic approaches to program/reprogram existing cell population to activate their therapeutic or regenerative potential or inhibit their deleterious effect in diseases such as muscular dystrophy. There are also other cases for rare disease applications that could be explored given the fast pace of tool development in the CRISPR field. The recent introduction of base editing and RNA editing significantly expanded the available mode of action of CRISPR-based technology and indicate the possibilities of even more fascinating areas of application (see other articles in this issue).

In retrospect, realization of these achievements in such a relatively short amount of time could be attributed to the innovative, nurturing, and visionary environment of many pioneering laboratories such as that of my own mentor Dr. Feng Zhang. All these labs in the field aim to foster trainees to take risks and constantly challenge the status quo. One example would be while we were working on simple one-target gene editing with CRISPR in the early days, we are already discussing ideas for scalable multiplexed engineering in a screen or thinking about other mode of action for the CRISPR system like RNA targeting. Both of these were later realized such as the Zhang laboratory's contribution to inventing Cas13a/Cas13b RNA-targeting CRISPR systems (which also saw several parallel studies from others in the field as a demonstration of their shared vision), which provided a possible solution to transiently or nongenetically engineer cells with more desirable safety profile.

One future critical area of focus, which I also plan to engage my own trainees and laboratory members on, would be the integration of efficient data analysis and computational tools with gene and cell therapy. This is not only critical for understanding the underlying disease mechanism that reveals the key druggable or editable target, but also extremely helpful for accelerating the pace of tool development in gene and cell therapy, exemplified by the recent adaptation of large-scale screening for CRISPR design, delivery vehicle designs, and pooled screening for hematotherapy targets, which all require sophisticated genomics data analysis and skill sets to be seamlessly connected with clinically relevant gene editing tools and models.