Gene-Editing Breakthrough Restores Sight in Blind Rats

blind-ratsIn a breakthrough that’s been described by researchers as the ‘Holy Grail’ of genetics, a team at the Salk Institute have successfully used gene-editing tool CRISPR to repair broken genes in the retinas of blind rats, partially restoring their sight. The same technique could be used to cure a range of genetic diseases, the researchers say.

Until now, DNA modifying techniques had only been successful in editing genes found in dividing cells, such as those in skin or the gut. However, most of our adult organs and tissues, such as the heart, brain and liver, are made up of cells that have stopped dividing, which makes it much harder to alter their DNA. This is the first time that researchers have been able to alter genetic material in such cells.

“We are very excited by the technology we discovered because it’s something that could not be done before,” said researcher Juan Carlos Izpisua Belmonte. “For the first time, we can enter into cells that do not divide and modify the DNA at will. The possible applications of this discovery are vast.”

The team tested their technique on rats engineered to have retinitis pigmentosa, a genetic form of blindness affecting about 1 in 4,000 humans in which faulty DNA causes cells in the retina to die. The researchers introduced a functional copy of one of the genes that is damaged in retinitis pigmentosa into the eyes of blind three-week-old rats. When the rats were eight weeks old, they were able to respond to light, and passed several tests indicating healing in their retinal cells.

“We now have a technology that allows us to modify the DNA of non-dividing cells, to fix broken genes in the brain, heart and liver,” said Izpisua Belmonte. “It allows us for the first time to be able to dream of curing diseases that we couldn’t before.”

However, while the technique shows great promise, human trials are still a long way off.