Monkeys cloned from a gene-edited macaque with circadian rhythm disorders are seen at the Chinese Academy of Sciences in Shanghai in this handout picture provided by the Institute of Neuroscience of the Chinese Academy of Sciences on January 24, 2019. Photo: VCG

Chinese researchers created a safe and efficient technology to edit RNA, which could largely avoid side effects and ethical concerns from previous gene-editing technologies. 

The achievement was released on Nature Biotechnology magazine on Monday, more than half a year after Chinese scientist He Jiankui claimed that he had created the world's first gene-edited twins immune to HIV, causing a global ethics whirlwind of condemnation and scorn. 

The technology He applied is called CRISPR-Cas9, which was adapted from a naturally occurring genome editing system in bacteria. Cas9 enzyme - a protein which plays a vital role in the immunological defense of certain bacteria against DNA viruses - would be introduced into the human body to cut the viruses' DNA.  

Such technology relies on the delivery of exogenous proteins or chemically modified guide RNAs, which may lead to aberrant effector activity, delivery barrier or immunogenicity, Wei Wensheng, a Peking University biologist and leading researcher of the latest technology, told the Global Times on Wednesday.

On the contrary, the latest technology, called leveraging endogenous ADAR for programmable editing of RNA (LEAPER), makes uses of native proteins and does not change DNA directly, thus would not bring about heritable changes and is precise and safe, Zhou Zhuo, another member of the research team, told the Global Times. 

LEAPER employs engineered RNAs to recruit native enzymes to change a specific adenosine to inosine, according to the website of Nature Biotechnology. 

Cellular-level experiments in the past two years had showed that LEAPER achieved editing efficiencies of up to 80 percent, according to Zhou. He said that the team is now testing LEAPER in rats. 

The LEAPER is active in a broad spectrum of cell types, including multiple human primary cell types, and can restore the deficient cells of patients with Hurler syndrome without evoking innate immune responses, the Nature Biotechnology website said. 

As a single-molecule system, LEAPER enables precise, efficient RNA editing with broad applicability for therapy and basic research, the website said.