Gene-Editing Breakthrough Partially Restores Sight To Blind Rats

Part of an adult mouse brain. The green portions are genome-edited neurons and the blue are cell nuclei. Salk Institute

Scientists have their sights set on a new gene-editing technique that combines the revolutionary CRISPR method with the ability to now target non-dividing cells – previously a very difficult task.

Hailed as a breakthrough in genetics research, CRISPR is a method that snips strands of DNA and replaces those with new genetic material. Until now, however, researchers struggled to use the technique on non-dividing cells, which account for the majority of adult organs and tissues.

“We are very excited by the technology we discovered because it’s something that could not be done before,” said senior author Juan Carlos Izpisua Belmonte, a professor at Salk’s Gene Expression Laboratory, in a statement. “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.”

Previously, techniques such as CRISPR Cas9 honed in on dividing cells. This new method, however, is 10 times more efficient on dividing cells and can modify non-dividing cells, according to the study published in the journal Nature.

The researchers paired a cellular pathway that repairs DNA breaks with existing gene-editing techniques in order to insert genes into non-dividing cells.

As proof of its efficacy and therapeutic potential, the researchers from Salk University devised a study to improve vision in rats with retinitis pigmentosa, an eye disease that causes progressive retinal degeneration.

In humans, the condition is an inherited disease that affects around one in 4,000. In those with retinitis pigmentosa, one of the genes that is damaged is called Mertk. The new gene-editing method, which the team calls HITI, replaced the defunct Mertk gene with a functional copy. After five weeks, the rats’ vision improved.

This improvement meant the rats now responded to light and that some of their retinal cells had healed. Although their sight was not fully restored, the new technique holds promise. Perhaps if administered sooner – when less degeneration has occurred – scientists could ward off or reduce future damage. 

This latest gene-editing advance comes on the heels of news that Chinese scientists are using CRISPR to edit genes in humans for the first time. It’s likely this novel HITI method will provide new avenues of research for various conditions, including retinal, heart, and neurological diseases.

“We were able to improve the vision of these blind rats,” said co-lead author Reyna Hernandez-Benitez, in the statement. “This early success suggests that this technology is very promising.”





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