New CRISPR tool edits RNA to treat diseases: study

WASHINGTON, Oct. 26 (Xinhua) -- U.S. researchers have developed a new version of the revolutionary gene-editing CRISPR tool for efficiently editing RNA, rather than DNA, in human cells, according to a study published Thursday in the U.S. journal Science.

Within cells, RNA is used to translate DNA's instructions into protein production. RNA editing is important because it doesn't result in permanent changes to people's genome, something required for DNA editing and causing ethical concerns.

"The ability to correct disease-causing mutations is one of the primary goals of genome editing," senior author Feng Zhang of the Broad Institute said in a statement.

"So far, we've gotten very good at inactivating genes, but actually recovering lost protein function is much more challenging. This new ability to edit RNA opens up more potential opportunities to recover that function and treat many diseases, in almost any kind of cell."

The new CRISPR-based system, called RNA Editing for Programmable A to I Replacement, or REPAIR, has the ability to target individual RNA letters, or nucleosides, switching adenosines to inosines, Zhang's team said.

These letters are involved in single-base changes known to regularly cause disease in humans, they said.

The researchers touted REPAIR as "a safer, more flexible" alternative for the five-year-old CRISPR tool.

"REPAIR can fix mutations without tampering with the genome, and because RNA naturally degrades, it's a potentially reversible fix," said co-first author David Cox, a graduate student in Zhang's lab.

To demonstrate REPAIR's therapeutic potential, the team synthesized the pathogenic mutations that cause Fanconi anemia and X-linked nephrogenic diabetes insipidus, introduced them into human cells, and successfully corrected these mutations at the RNA level.

To push the therapeutic prospects further, the team plans to improve REPAIR's efficiency and to package it into a delivery system appropriate for introducing REPAIR into specific tissues in animal models.