The researchers from the City of Hope may have found a way to sharpen the cheapest, fastest, and most accurate gene-editing tool called the CRISPR-Cas9 so that it can successfully cut out undesirable genetic information. This cutting ability was improved so that one day, experts can fast-track potential therapies for sickle cell disease, HIV, and other immune conditions.
What is the CRISPR-Cas9 design
Tristan Scott, Ph.D., lead author of the study and a staff research scientist at City of Hope's Center for Gene Therapy, said that the CRISPR-Cas9 design might be the difference between trying to cut a rib eye steak with a butter knife versus cutting it with a steak knife. Other scientists have tried to improve CRISPR cutting through chemical modifications, but that is an expensive process, and it is like diamond-coating a blade. Scientists have designed a better pair of scissors that people can buy easily anywhere.
The study that was done by Dr. Scott and his team was published in Scientific Reports, and it is the first time scientists have systematically gone through the guide RNA sequence to change it and to improve CRISPR-Cas9 technology. A patent application was filed at The Kevin Morris Lab at City of Hope, claiming this improved CRISPR-Cas9 design, which could result in a doubling of activity, but the exact amount was dependent on the target site.
The effects of this CRISPR-Cas9 design is downstream as it has more "clean" results in mouse model and cell experiments aimed at making new therapies because the target that was knocked out was more successfully removed. More results could quicken new therapies from the laboratory to patients' bedsides. The therapeutic product should have successful cuts, which could mean that an improved therapy is on the way, but further research is still needed. The exact ways and process of why this change to the CRISPR system improves gene editing still needs to be determined.
Experiments through nanotechnology
The researchers of the study experimented on cells by making certain changes to the tracrRNA or trans-activating CRISPR RNA which they got from Streptococcus pyogenes bacteria, and it is a part of the components that are used to guide the genetic scissors, also known as Cas 9, to the right gene sequence. Streptococcus pyogenes Cas9 is the most widely used genetic scissor. Dr. Scott and his team used an RNA protein system because it gives an increase of activity that disappears about 12 hours after being introduced into the cell, which means that there is a decreased chance of accidentally editing the human gene later after the fix has been made.
Scientists found that the modified tracrRNA improved the overall silencing of certain genes by increasing desirable mutations in the genetic material. In this study, the target was an essential component of HIV's lifecycle, the protein CCR5 on immune CD4+ T-cells—a current target in clinical trials seeking to re-create a person's immune system so they can be resistant to HIV. The modified tracrRNA had improved the overall cutting at this site and inactivation of CCR5, and hopefully, that will translate into better protection for the immune system.
The new tracrRNA design is better at improving the activity at the HBB gene and the BCL11A site. The HBB gene, which is responsible for producing beta-globin that is located inside red blood cells, and BCL11A, which may function as a leukemia disease gene, are targeted by the tracrRNA in order to make different therapies for HIV, which is known as a blood disease that does not have any known cure yet.
Dr. Scott stated that if the line of research remains consistent, and they can dependably sharpen the genetic scissor, the result could eventually be new or improved genetic therapies. He also said that his team is at the beginning of a long scientific process.
