As eVLP enables safer delivery of gene editing agents in vivo than some methods used in the clinic, with equal or greater efficacy, this new platform is a promising technology. to deliver therapeutic macromolecules in live animals with minimal risk of DNA misdirection or integration.
In the paper, published in Cabinet, The researchers detail how they developed virus-like particles to provide base editors, proteins that induce programmable single-character changes in DNA, and CRISPR-Cas9 nuclease, a protein that cuts DNA at targeted locations in the genome. The authors identified factors that influence the efficiency of virus seed delivery and demonstrated that engineered virus seeds can overcome many structural limitations to their potency.
“The introduction of therapeutic macromolecules into mammalian cells in animals and ultimately in patients is one of the most important challenges in the life sciences.” David Liu, lead author of the paper, said Thomas Dudley Cabot, Professor of Natural Sciences, and a core faculty member of the Broad Institute. “There is often a huge disparity between delivery in vitro and in vivo, so we decided early on that our new delivery technology would need to show good performance in dynamic models. object.”
This work was led by members of Liu’s lab, including postdoctoral fellow Samagya Banskota, and graduate student Aditya Raguram, in collaboration with research teams led by Krzysztof Palczewski at the University of California, Berkeley. Irvine, and Kiran Musunuru at the Perelman School of Medicine at the University of Pennsylvania.
This new delivery system finds a new use for virus-like elements and builds on the success of the base editors, which Liu Lab developed in 2016 to rewrite the engines. individual DNA bases, such as the mutations that cause thousands of genetic diseases.
Virus seeds, collections of viral proteins that can infect cells but lack the viral genetic material, have long been studied as vehicles for drug delivery. Because they can transport molecular cargo and have no viral genetic material, they can effectively exploit the tissue-targeting advantage of virus delivery without the disadvantages of using real viruses. cells, can insert their genetic material into the cell’s genome and potentially cause cancer. However, current VLP delivery strategies have limited therapeutic efficacy in vivo.
To successfully implement VLPs, the team identified shipping limits and systematically designed VLP components to overcome packaging, release, and localization bottlenecks. In doing so, they developed a fourth-generation eVLP that encapsulates 16 times more cargo proteins than previous designs and enables an 8 to 26-fold increase in editing efficiency in cells and animals. time.
The team tested their optimized eVLP system to deliver base editors to the liver in mice, where they effectively edited a gene that can lower “bad” cholesterol levels. A single injection of eVLPs resulted in an average 63% correction of the target gene and a 78% reduction in its protein levels, which significantly reduces the risk of coronary heart disease.
“The cholesterol target is particularly interesting because it’s not just relevant for patients with rare genetic diseases,” says Raguram. “We hope this is an example of how genome editing can benefit a large population because cholesterol levels affect the health of billions of people.”
The researchers also used a single injection of eVLP to correct the pathogenic point mutation in mice with an inherited retinal disorder. They effectively corrected point mutations with less biased target editing than other baseline editing distribution techniques, resulting in partial restoration of vision.
The team also injected eVLPs directly into the brains of mice and observed an editing efficiency of about 50% in cells exposed to eVLPs.
Going forward, Banskota is optimistic that eVLPs will be used fairly easily by scientists because of the system’s relative simplicity and its flexibility.
“Because our system is relatively simple and easy to design, it allows other scientists to quickly adopt and build on this technology,” says Banskota. “In addition to carrying gene editors, eVLP has the potential to transport other macromolecules with a great deal of therapeutic potential.”