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Trial Testing Retina Cell Implants for Glaucoma


Optometrist (David Mark, Pixabay)

14 October 2016. A new clinical trial is testing implants to treat glaucoma made of genetically engineered retina cells that release hormones promoting optic nerve growth. The trial, being conducted by Stanford University, is supported by the BrightFocus Foundation in Clarksburg, Maryland.

Glaucoma is the name given to a collection of eye conditions resulting in damage to the optic nerve that in advanced stages can lead to vision loss. According to statistics cited by Glaucoma Research Foundation, glaucoma affects more than 3 million people in the U.S., accounting for 9 to 12 percent of all cases of blindness. Blindness from glaucoma is 6 to 8 times more common among people of African descent in the U.S. than Caucasians. It is also the second leading cause of blindness in the world, according to World Health Organization.

Most treatments for glaucoma aim to relieve pressure that builds up and causes damage to the optic nerve. In this trial, the team led by ophthalmologist Jeffrey Goldberg, director of Stanford’s eye institute, is testing an implant in the eye of stem cells genetically engineered to release the protein ciliary neurotrophic factor. This hormone is normally released in the retina under stressful conditions, such as trauma to the eye, and signals protection for neural tissue, including the retina.

For this treatment, ciliary neurotrophic factor is derived from a line of cells produced by the company Neurotech Pharmaceuticals in Cumberland, Rhode Island. Neurotech developed a therapy for retinal degenerative diseases code-named NT-501 ECT made of genetically-engineered human retinal cells placed in a tiny biocompatible plastic capsule implanted in the back of the eye.

After implantation with an outpatient surgical procedure, the cells produce ciliary neurotrophic factor secreted in the region of damage to the optic nerve. Neurotech says its preclinical and early-stage human trials show NT-501 ECT treatments protect photoreceptors — cells detecting light in the retina — and retinal ganglion cells, or RGCs, which slow vision loss. The company adds the engineered cells release the hormone for more than 2 years.

The intermediate-stage clinical trial at Stanford in Palo Alto, California is recruiting 60 individuals with glaucoma, randomized to receive NT-501 ECT or sham cell implants. Participants will be tracked for 6 months, first testing primarily for changes in visual field over that period, then followed for another 18 months. Patients will also be evaluated for thickness and structure of RGCs, and related variables.

“We have no approved treatments that address the degeneration of the RGCs or their axons,” says Goldberg in a BrightFocus statement, “so this is a huge unmet need.” Goldberg adds that delivering growth factors, “directly to the eye, without significant exposure to the rest of the body, is a significant advantage of the NT-501 implant approach.”

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