Efficient genetic editing developed

As potential next-generation therapeutics and research tools, few life sciences technologies hold more promise than genome-editing proteins -- molecules that can be programmed to alter specific genes in order to treat or even cure genetic diseases.

There's at least one catch though -- getting genome-editing proteins into cells, where they need to be to access the genome, is a major challenge, especially in live animals or human patients.

Conventionally, researchers have delivered the DNA encoding these genome-editing proteins into cells and then relied on the cells to produce the corresponding genome-editing proteins. But many DNA delivery strategies cannot be used in animals or human patients. Other DNA delivery strategies such as infecting with viruses that inject DNA into cells can raise complicating long-term safety issues, especially when the editing the human genome is involved.

What may be more promising, the new study finds, is the direct delivery of genome-editing proteins into cells, rather than delivery of the corresponding genes that encode these proteins. And a class of molecules that can open the door for genome-editing proteins, as it turns out, is probably already on the shelves of many biologists.

Led by Professor of Chemistry and Chemical Biology David Liu and his group members Drs. John Zuris and David Thompson, a team of Harvard researchers have developed a system that uses commercially-available molecules called cationic lipids -- essentially long, greasy molecules that carry a positive charge at one end -- to efficiently introduce genome-editing proteins into cells, and have even demonstrated that the technology can be used to modify genes in living animals. The study is described in an October 30 paper in Nature Biotechnology.

"Current drugs that treat genetic diseases cannot address the root cause of the disease," Liu explained. "Unlike infectious diseases, for example, which we treat by killing the disease-causing agent, in the case of diseases that come from mutations in our own genes, one has to go into the cells and do surgery on our genomes to fix the root cause. Thanks to recent discoveries by scientists around the world, we now have genome-editing proteins that can do the surgery. But the challenge is that these proteins, like virtually all proteins, do not enter cells spontaneously.

"In this study we describe a method to very potently deliver genome-editing proteins into cells," Liu added. "And we observed efficient genome modification using this method not just in cultured cells, but also in living animals."

Though he warned that no system, including this one, will be a one-size-fits-all delivery solution, Liu believes that delivering genome-editing proteins into cells could offer hope to patients suffering from a host of conditions, including certain diseases of the eye, ear, liver, muscles, and blood.

One condition that's already in researchers' crosshairs is deafness.

Working with Zheng-Yi Chen, an Associate Professor of Otology and Laryngology at Harvard Medical School and researcher at Massachusetts Eye and Ear Infirmary, Liu and colleagues used the newly-developed system to modify genes in specialized "hair cells" in the inner ear of mice. Hair cell damage, either from environmental or genetic factors, is a common cause of hearing loss.

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Efficient genetic editing developed