Scientists from MIT have tested a nanoparticle delivery system for the CRISPR genome editing-system in mice that eliminates the need to use viruses for delivery. In a paper published in the November 13 edition of Nature Biotechnology, the team reports that they were able to use the new technique to cut out target genes in about 80% of liver cells.
"What's really exciting here is that we've shown you can make a nanoparticle that can be used to permanently and specifically edit the DNA in the liver of an adult animal," says Daniel Anderson, an associate professor in MIT's Department of Chemical Engineering and a member of MIT's Koch Institute for Integrative Cancer Research and Institute for Medical Engineering and Science (IMES).
In order to deliver the guide RNA (sgRNA), the team had to modify it to protect it from enzymes in the body that would normally break it down. They tested many possible sgRNA modifications before arriving at a structure that could withstand the body’s enzymes without affecting its ability to bind to Cas9.
Once that was done, they packaged the RNA guides into lipid nanoparticles, which they injected into mice along with nanoparticles containing the mRNA that encodes Cas9. They used this method to target a gene called Pcsk9, which regulates cholesterol levels in humans. Mutations in this gene are known to lead to a rare disorder called dominant familial hypercholesterolemia.
According to the team, they were able to eliminate the Pcsk9 gene in more than 80% of liver cells with this technique and Pcsk9 protein was undetected in these mice. They also found a 35% drop in total cholesterol levels in the test mice.
The researchers plan to focus future efforts on determining other liver diseases that this method might be used for and advancing this approach for use in human patients.
Image: In a new study, MIT researchers have developed nanoparticles that can deliver the CRISPR genome-editing system and specifically modify genes, eliminating the need to use viruses for delivery. Image courtesy of MIT News.