WASHINGTON (Dispatches)-Researchers have developed a new technique for the powerful gene editing tool CRISPR to restore retinal function in mice afflicted by a degenerative retinal disease, retinitis pigmentosa.
Researchers from Columbia University have successfully applied CRISPR technology to a type of inherited disease known as a dominant disorder. This same tool might work in hundreds of diseases, including Huntington's disease, Marfan syndrome, and corneal dystrophies.
Since it was introduced in 2012, the gene editing technology known as CRISPR (Clustered Regularly Interspaced Short Palindromic Repeats) has revolutionized the speed and scope with which scientists can modify the DNA of living cells. Scientists have used it on a wide range of applications, from engineering plants (seedless tomatoes) to producing animals (extra lean piglets). But as incredible as genome surgery is, CRISPR has some flaws to overcome before it can live up to its hype of curing disease in humans by simply cutting out bad genes and sewing in good ones.
Typically, CRISPR researchers design a short sequence of code called guide RNA that matches the bit they want to replace. They attach the guide RNA to a protein called Cas9, and together they roam the cell's nucleus until they find a matching piece of DNA. Cas9 unzips the DNA and pushes in the guide RNA. It then snips out the bad code and coaxes the cell to accept the good code, using the cell's natural gene repair machinery.
This technique allowed for a larger deletion of genetic code that permanently destroyed the targeted gene. Dr. Stephen H. Tsang from Columbia University found that using two guide RNAs instead of one increased the chance of disrupting the bad gene from 30 percent to 90 percent. They combined this genome surgery tool with a gene replacement technique using an adeno-associated virus to carry a healthy version of the gene into the retina.