NPR News recently featured an article announcing that scientists at Portland’s Casey Eye Institute have attempted to use CRISPR to edit a gene with the DNA still in place. This is a first-time event.
This first attempt has been well-received by the scientific community. Previously, the cells were removed and the genes were edited in the lab outside of the body. They were then reinfused and would either attack the cancer in the body or replace a missing protein. Until now, doctors limited the use of CRISPR to cancer patients or patients with rare blood diseases such as beta-thalassemia.
Leber Congenital Amaurosis TYPE 10
The recipient of the first procedure is legally blind from a disorder called Leber congenital amaurosis (LCA). This rare disorder generally begins in infancy and attacks light-sensing cells of the retina which are critical for vision.
Although LCA impairment varies, the majority of patients become legally blind.
A Groundbreaking Procedure
Tiny incisions allow access to the back of the eye. CRISPR-loaded fluid is injected into photoreceptor cells behind the retina. Three droplets of the fluid contain billions of copies of harmless modified virus carrying gene-editing instructions. The procedure takes one hour.
After the fluid has been injected, CRISPR editing goes to work and removes the defective mutation in the CEP290 gene. This gene provides instructions for replacing missing proteins.
The researchers expect some results in several weeks and will know in several months how much of the patient’s vision will be restored.
They are hoping the technique will produce a critical protein inside the retina which will be capable of preventing cells from dying. They are also attempting to revive existing cells. Their goal with this one procedure is to improve the patient’s vision for life.
Since this is an entirely new procedure, the researchers are administering a low dose. They are also starting with elderly patients whose vision is severely damaged and limiting the procedure to only one of the patient’s eyes. If the procedure is a success, the patient’s may undergo treatment on their other eye.
Editas Medicine based in Cambridge, Mass., is the sponsor of the study which will eventually total eighteen patients. Some of these patients will be three to seventeen years of age.
Children may benefit the most from the therapy because, as the scientists point out, a child’s visual pathway is still intact.
About CRISPR
The scientists involved with the study are pioneers in gene-editing and believe that it will impact many areas of medicine. One of the researchers in the study explained that the revolutionary CRISPR technique facilitates the rewriting of the genetic code and gives hopes to curing a variety of diseases.
He said that being able to directly edit within the body paves the way for new therapies to treat diseases where there are no approved treatments available. That list is long and includes Huntington’s disease, myotonic dystrophy, muscular dystrophy, and various forms of dementia.
The scientists hope that gene-editing will be long lasting but they admit that it is so new the results are unknown.
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