Researchers have enhanced a gene-editing technology to the point where it can efficiently insert or replace entire genes in the genome of human cells. This improvement holds the potential to be valuable for therapeutic purposes. In the future, this advancement could aid in the development of a single gene therapy for diseases like cystic fibrosis, which are caused by numerous mutations in a gene. With this new approach, a healthy version of the gene would be inserted at its natural location in the genome, eliminating the need to create individual gene therapies for each mutation using other gene-editing methods that make smaller changes.
Researchers at the Broad Institute of MIT and Harvard have upgraded a gene-editing technology that now has the ability to efficiently insert or replace entire genes in the human cell’s genome, making it potentially valuable for therapeutic purposes.
The progress, led by Broad core institute member David Liu, may one day aid in the development of a singular gene therapy for diseases like cystic fibrosis, which are caused by numerous mutations in a gene. With this new method, a healthy version of the gene could be inserted at …The groundbreaking technique, known as eePASSIGE, utilizes prime editing in conjunction with recombinase enzymes to efficiently insert large DNA segments at specific locations in the genome. This innovative approach allows for a wide range of edits up to 100 or 200 base pairs, making gene-sized edits several times more efficient than other methods. The findings were published in Nature Biomedical Engineering.This is one of the earliest instances of programmable targeted gene integration in mammalian cells that meets the main criteria for potential therapeutic significance,” explained Liu, who is the senior author of the study, the Richard Merkin Professor and director of the Merkin Institute of Transformative Technologies in Healthcare at the Broad, a professor at Harvard University, and a Howard Hughes Medical Institute investigator. “With these high success rates, we anticipate that numerous, if not most, loss-of-function genetic diseases could be improved or cured, if the efficiency we see in cultured human cells can be applied to clinical settings.The study had co-first authors Smriti Pandey, a graduate student, and Daniel Gao, a postdoctoral researcher, both from Liu’s group. The research was a collaboration with Mark Osborn’s group at the University of Minnesota and Elliot Chaikof’s group at the Beth Israel Deaconess Medical Center. Pandey expressed optimism about the potential of the system in cell therapies, as it can be used to accurately insert genes into cells outside of the body before being given to patients for treatment. She also mentioned the system’s high efficiency and versatility, which could open up new possibilities.”Genomic medicines,” Gao added. “We also hope that it will be a tool that scientists from across the research community can use to study basic biological questions.”
Key advancements
Many scientists have utilized prime editing to effectively make changes to DNA that are up to dozens of base pairs in length, capable of correcting the majority of known pathogenic mutations. However, the longstanding goal of the gene-editing field has been to introduce entire healthy genes, often thousands of base pairs long, in their original location in the genome. This has the potential to greatly expand the capabilities of genomic medicine.has developed a prime editing approach called twinPE, which has the potential to treat patients with disease-causing gene mutations. This approach aims to preserve surrounding DNA sequences and regulate the newly installed gene properly. In 2021, Liu’s lab reported a key step towards this goal by installing recombinase “landing sites” in the genome using natural recombinase enzymes such as Bxb1 to insert new DNA into the prime edited target sites. Prime Medi, a biotech company, is involved in this development.Liu and his co-founder developed a technology called PASSIGE (prime-editing-assisted site-specific integrase gene editing) and used it to work on treatments for genetic diseases. PASSIGE was effective in making edits in a small number of cells, which could help treat some genetic diseases caused by the loss of a functioning gene. However, to improve the efficiency of PASSIGE, Liu’s team identified the recombinase enzyme Bxb1 as the factor limiting its effectiveness. They then utilized a tool called PACE (phage-assisted continuous evolution) previously developed by Liu’s group to address this issue.Liu and his team used a method called continuous evolution to quickly develop more effective versions of Bxb1 in the laboratory. The result was a newly evolved and engineered Bxb1 variant (eeBxb1) which improved the eePASSIGE method, allowing for the integration of an average of 30 percent of gene-sized cargo in both mouse and human cells. This is four times more efficient than the original technique and about 16 times more efficient than another recently published method called PASTE. According to Liu, “The eePASSIGE system provides a promising foundation for studies integrating healthy gene copies at sites of our choosing in cell and animal models of genetic diseases to treat loss-of-function disorders.”It is considered a crucial development in achieving the advantages of specific gene integration for patients.”
With this objective in mind, Liu’s team is currently focusing on merging eePASSIGE with delivery systems like engineered virus-like particles (eVLPs) that could potentially overcome obstacles that have historically restricted the therapeutic delivery of gene editors in the body.
